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Encephalitis From Wikipedia, the free encyclopedia Encephalitis is an acute inflammation of the brain, commonly caused by a viral infection. It can be caused by a bacterial infection such as bacterial meningitis, or may be a complication of other infectious diseases like rabies (viral) or syphilis (bacterial). Certain parasitic or protozoal infestations, such as toxoplasmosis, malaria, or primary amoebic meningoencephalitis, can also cause encephalitis in people with compromised immune systems. Brain damage occurs as the inflamed brain pushes against the skull, and can lead to death.

Symptoms Patients with encephalitis suffer from fever, headache and photophobia with weakness and seizures also common. Less commonly, stiffness of the neck can occur with rare cases of patients also suffering from stiffness of the limbs, slowness in movement and clumsiness depending on which specific part of the brain is involved. The symptoms of encephalitis are caused by the brain's defense mechanisms activating to get rid of the infection. Another symptom of Encephalitis is hallucination.

Etiology Encephalitis may be caused by a variety of afflictions. One such affliction is rabies. Encephalitis may also be caused by HIV. The major causes of encephalitis outbreaks all over the world are viruses like Japanese Encephalitis, West Nile, Chandipura,St. Louis Encephalitis, Equine Encephalitis, La Crosse encephalitis, Murray Valley encephalitis virus, California encephalitis virus, Tick-borne meningoencephalitis, Herpes simplex, Influenza A virus etc.

Diagnosis Adult patients with encephalitis present with acute onset of fever, headache, confusion, and sometimes seizures. Younger children or infants may present with irritability, anorexia and fever.

Neurological examinations usually reveal a drowsy or confused patient. Stiff neck, due to the irritation of the meninges covering the brain, indicates that the patient has either meningitis or meningeoncephalitis. Examination of the cerebrospinal fluid obtained by a lumbar puncture procedure usually reveals increased amounts of protein and white blood 1

cells with normal glucose, though in a significant percentage of patients, the cerebrospinal fluid may be Spondylitis What is spondylitis? Spondylitis (also called ankylosing spondylitis) is a type of arthritis that affects the spine or backbone. Spondylitis may cause back pain and stiffness. The bones of the spine, called vertebrae, may grow or fuse together resulting in a rigid spine. These changes may be mild or severe. Severe disease may lead to poor posture and deformities. Early diagnosis and treatment helps control pain and stiffness, and may reduce or prevent significant deformity. Who is affected by spondylitis? Spondylitis affects about three hundred thousand Americans or 0.2% of the adult population. Although it can occur at any age, spondylitis most often affects men in their 20s and 30s. It is less common and generally milder in women. It is more common in Caucasians than in African Americans. What are the signs and symptoms of spondylitis? The most common early signs of spondylitis are constant pain and stiffness in the low back, buttocks and hips that continue for more than three months. Spondylitis often starts around the sacroiliac ts where the sacrum (the lowest major part of the spine) s the ilium of the pelvic bone. Spondylitis can cause an overgrowth of the bones, which may lead to abnormal ing of parts that are normally separate. This is called bony "fusion." Fusion affecting bones of the neck, back or hips may impair a person's ability to perform routine activities. Fusion of the ribs to the spine or breastbone may limit a person's ability to expand his or her chest when taking a deep breath. Spondylitis may also affect some of the ligaments and tendons that attach to bones. Tendonitis (inflammation of the tendon) may cause pain and stiffness in the area behind or beneath the heel, such as the Achilles tendon at the back of the ankle. Spondylitis is a systemic disease, which means symptoms may not be limited to the ts. Patients may also have a fever, fatigue and loss of appetite. Eye inflammation (redness) occurs in about one-fourth of patients with spondylitis. In rare cases, lung and heart problems may also develop. What causes spondylitis? Although the cause of spondylitis is unknown, there is a strong genetic or family link. Most, but not all, patients with spondylitis carry a gene called HLA-

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B27. Although people carrying this gene are at increased risk of developing spondylitis, the majority (over 75%) will never develop the disease. How is spondylitis diagnosed? The diagnosis of spondylitis is based on several factors, including: • •

Presence of signs and symptoms as noted previously Findings on physical examination and X-rays

How is spondylitis treated? There is no cure for spondylitis, but discomfort can be reduced and function can often be improved. The goals of treatment are to: • • • •

Reduce pain and stiffness Maintain a good posture Prevent deformity Preserve one's ability to perform normal activities

When properly treated, people with spondylitis may lead fairly normal lives. Under ideal circumstances, a team approach to treat spondylitis is desirable. of the treatment team typically include the patient, doctor, physical therapist and occupational therapist. Physical and occupational therapy Early intervention with physical and occupational therapy is important to maintain function and minimize deformity. The patient should try to maintain normal posture. Patients with spondylitis are encouraged to sleep on a hard mattress with their back straight. Placing large pillows under the head is discouraged, since it may promote neck fusion in flexion. Similarly, propping the legs up on pillows should be avoided as it may lead to hip and/or knee fusion in a bent position. When sitting, chairs, tables and other work surfaces should be designed to avoid slumping or stooping. Armchairs are preferred over chairs without arms. Since patients with spondylitis could easily hurt their rigid necks or backs, special care should be taken to avoid sudden impact, such as jumping, or falling. Exercise A program of daily exercise will help reduce stiffness, strengthen the muscles around the ts, and prevent or minimize the risk of disability. Deep breathing exercises may help keep the chest cage flexible. Swimming is an excellent form of exercise for patients with spondylitis.

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Medications While a cure for spondylitis is not available, certain drugs help provide relief from pain and stiffness and allow patients to perform their exercises with minimal discomfort. Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly used drugs for spondylitis treatment. NSAIDs are not related to cortisone (a steroid), although both work by reducing inflammation. A variety of NSAIDs are currently available, and the choice of a particular drug should be discussed with the treating doctor. In severe cases, other medications may be added to the treatment regimen. Other treatments Patients experiencing eye inflammation (red eye) should be evaluated and treated by an ophthalmologist (eye doctor). Patients are urged to not smoke or chew tobacco products because of the increased risk of lung problems and reduced chest cage expansion. Certainly, all of the other reasons why doctors discourage smoking also apply to spondylitis patients. Artificial t replacement surgery may be a treatment option for certain patients with advanced t disease affecting the hips or knees. Patients are encouraged to discuss coping strategies, work-related issues, sexuality and other important concerns with their health care team. normal. CT scan often is not helpful, as cerebral abscess is uncommon. Cerebral abscess is more common in patients with meningitis than encephalitis. Bleeding is also uncommon except in patients with herpes simplex type 1 encephalitis. Magnetic resonance imaging offers better resolution. In patients with herpes simplex encephalitis, electroencephalograph may show sharp waves in one or both of the temporal lobes. Lumbar puncture procedure is performed only after the possibility of prominent brain swelling is excluded by a CT scan examination. Diagnosis is often made with detection of antibodies in the cerebrospinal fluid against a specific viral agent (such as herpes simplex virus) or by polymerase chain reaction that amplifies the RNA or DNA of the virus responsible (such as varicella zoster virus).

Treatment Treatment is usually symptomatic. Reliably tested specific antiviral agents are available only for a few viral agents (e.g. acyclovir for herpes simplex virus) and are used with limited success for most infection except herpes simplex encephalitis. In patients who are very sick, ive treatment, such as mechanical ventilation, is equally important.

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Encephalitis lethargica Encephalitis lethargica is an atypical form of encephalitis which caused an epidemic from 1917 to 1928. There have only been a small number of isolated cases since, though in recent years a few patients have shown very similar symptoms. The cause is now thought to be either a bacterial agent or an autoimmune response following infection.

Limbic system encephalitis In a small number of cases, called limbic encephalitis, the pathogens responsible for encephalitis attack primarily the limbic system (a collection of structures at the base of the brain responsible for basic autonomic functions).

Encephalitis Although the term "encephalitis" literally means "inflammation of the brain," it usually refers to brain inflammation resulting from a viral infection. The severe and potentially life-threatening form of this disease is rare. Experts suspect that the actual incidence of encephalitis is probably much higher — but because most people have such mild signs or symptoms, many cases go unrecognized. Encephalitis occurs in two forms — a primary form and a secondary form. Primary encephalitis involves direct viral infection of your brain and spinal cord. In secondary encephalitis, a viral infection first occurs elsewhere in your body and then travels to your brain. Seeing your doctor and receiving timely treatment is important because the course of the disease is unpredictable

Signs and symptoms Most people infected with viral encephalitis have only mild symptoms — headache, irritability or lethargy — or no symptoms, and the illness doesn't last long. Serious cases can cause: • Drowsiness • Confusion and disorientation • Seizures • Sudden fever • Severe headache • Nausea and vomiting • Stiff neck

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Bulging in the soft spots (fontanels) of the skull in infants

Urgent signs and symptoms in adults may include altered levels of consciousness or mental disturbances. In infants, the key signs are a stiff neck and a bulging in the soft spots of the skull. In older children, watch for severe headaches, sudden personality changes, confusion and sensitivity to light.

Causes The cause of encephalitis is most often a viral infection. Some examples include herpes viruses; arboviruses transmitted by mosquitoes, ticks and other insects; and rabies transmitted through animal bites. Encephalitis takes two forms, categorized by the two ways that viruses can infect your brain: •

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Primary encephalitis. This occurs when a virus directly invades your brain and spinal cord. It can happen to people at any time of the year (sporadic encephalitis), or it can be part of an outbreak (epidemic encephalitis). Secondary (post-infectious) encephalitis. This form occurs when a virus first infects another part of your body and secondarily enters your brain.

Also, bacterial infections, such as Lyme disease, can sometimes lead to encephalitis, as can parasitic infections, such as toxoplasmosis (in people with weakened immune systems). Here are some of the more common causes of encephalitis: Herpes viruses Some herpes viruses that cause common infections may also cause encephalitis. These include: •

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Herpes simplex virus. There are two types of herpes simplex virus (HSV) infections. HSV type 1 (HSV-1) more commonly causes cold sores or fever blisters around your mouth. HSV type 2 (HSV-2) more commonly causes genital herpes. HSV-1 is the most important cause of fatal sporadic encephalitis in the United States, but it's also rare. Varicella-zoster virus. This virus is responsible for chickenpox and shingles. It can cause encephalitis in adults and children, but tends to be mild. Epstein-Barr virus. This herpes virus causes infectious mononucleosis (mono). If encephalitis develops, it's usually mild, but can be fatal in a small number of cases.

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Childhood infections In rare instances, secondary encephalitis occurs after vaccine-preventable childhood viral infections, including: • • •

Measles (rubeola) Mumps Rubella (German measles)

In such cases, encephalitis may be due to hypersensitivity — an overreaction of your immune system to a foreign substance. Arboviruses Viruses that are transmitted by mosquitoes and ticks (arboviruses) have, in recent years, produced well-publicized encephalitis epidemics. Still, this type of encephalitis is fairly uncommon. Here's how the transmission cycle works: Organisms that transmit disease from one animal host to another are called vectors. Mosquitoes are vectors for the transmission of encephalitis from small creatures — usually birds and rodents — to humans. Birds that live near bodies of standing water, such as freshwater swamps, are susceptible to infection with an encephalitis virus. When a bird is infected with encephalitis, it carries high levels of the virus in its blood for a short time before recovering from the infection and developing immunity to the disease. If a mosquito feeds on an infected bird, the mosquito becomes a lifelong carrier of the disease. The mosquito transmits the infection to the next bird it feeds on, which in turn es it to more mosquitoes. Usually, this transmission pattern cycles through without serious impact on either creature and without affecting humans. This is partly because mosquitoes' primary hosts are birds and small mammals, and they bite humans only as a second choice. But sometimes environmental disasters, unusual weather or other climate changes cause an increase in the number of infected birds, as well as an increased number of mosquitoes. Under these conditions, humans may be affected. In the United States, the following types of mosquito-borne encephalitis occur: •

Eastern equine encephalitis. This infection generally afflicts horses and birds, especially birds that live near freshwater swamps. It can also affect humans, although fewer than 10 cases are reported in most years. Eastern equine encephalitis outbreaks occur most commonly in the eastern United States . Although some people experience it only as a mild illness, eastern equine encephalitis is fatal in about half the people who develop severe signs and symptoms. Symptoms of eastern equine

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encephalitis usually appear four to 10 days after a bite by an infected mosquito. Western equine encephalitis. Most reports of western equine encephalitis come from the central and western Plains of the United States. Like eastern equine encephalitis, this infection affects horses and, rarely, humans. It flourishes in birds that live near irrigated fields and farming areas. Symptoms appear between five and 10 days after a bite. Western equine encephalitis is less likely to be fatal than is its eastern cousin, but can result in brain damage and other major complications, particularly in infants. St. Louis encephalitis. This virus is transmitted to mosquitoes by birds. The mosquito vector of St. Louis encephalitis breeds in areas of standing water, including polluted pools, roadside ditches and containers such as birdbaths, flowerpots and discarded tires. About three dozen cases are reported each year in the United States, although severe outbreaks have affected up to 3,000 people in one year. Symptoms appear within a week to 10 days. Although many young people have mild or no symptoms when infected, the disease can be severe in adults older than 60. The mortality rate is between 3 percent and 20 percent. Older adults have a higher mortality rate from St. Louis encephalitis. La Crosse encephalitis. This virus is named for La Crosse, Wis., where the virus was first recognized in 1963. It's most common in the hardwood forest areas of the Upper Midwest and in Appalachia. Unlike other forms of viral encephalitis, this virus is ed to mosquitoes from chipmunks and squirrels. La Crosse encephalitis usually affects children and is rarely fatal. About 100 cases are reported annually. Symptoms appear five to 15 days after a bite by an infected mosquito. West Nile encephalitis. This virus first appeared in the United States in 1999 and spread across most of the country over the next several years. It's also found in Africa and the Middle East and in parts of Europe, Russia, India and Indonesia. The virus is similar to other encephalitis viruses in that birds are its main animal hosts. However, in rare cases, it's possible for the disease to spread from person to person through organ transplant, blood transfusions or breast-feeding, or from mother to unborn child. Symptoms of West Nile encephalitis are generally mild, but the disease can be severe, especially in older adults and those with weakened immune systems. Symptoms appear within five to 15 days of being bitten by an infected mosquito. Less than 1 percent of people get severe disease from the West Nile virus. Those most at risk are people over 50 and those with suppressed immune systems.

Risk factors Mosquitoes don't discriminate, so anyone can develop viral encephalitis. But some factors put you at greater risk:

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Age. Some types of encephalitis are more prevalent or more severe in young children or older adults. Weakened immune system. If you have an immune deficiency — for example, because of AIDS or HIV — or you're going through cancer therapies or organ transplantation, you're more susceptible to encephalitis. Geographic regions. Visiting or living in areas of the country where mosquito-borne viruses are common increases your risk of epidemic encephalitis. Outdoor activities. If you have an outdoor job or open-air hobby, such as gardening, jogging, golf or bird-watching, be extra careful during an encephalitis outbreak. Season of the year. The warm months of summer are the prime mating time for birds and mosquitoes. As a result, mosquito-borne diseases are more prevalent from the summer months in many areas of the United States.

Screening and diagnosis Diagnosing encephalitis may involve: •

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Spinal tap (lumbar puncture). One common way to diagnose encephalitis is to analyze the cerebrospinal fluid surrounding your brain and spinal cord. A needle inserted into your lower spine (below the level of the spinal cord) extracts a sample of fluid for laboratory analysis, which may reveal the presence of an infection or an increased white blood count — a signal that your immune system is fighting an infection. Your cerebrospinal fluid may also be slightly bloody if hemorrhages have occurred. Diagnosis of herpes simplex encephalitis can be difficult, but advances in using sensitive DNA methods have allowed detection of the virus in spinal fluid. Electroencephalography (EEG). This procedure measures the waves of electrical activity produced by your brain. It's often used to diagnose and manage seizure disorders. A number of small electrodes are attached to your scalp with paste or an elastic cap as you recline. You remain still during the test, but at times you may be asked to breathe deeply and steadily for several minutes or to stare at a patterned board. At times, a light may be flashed in your eyes. These actions are meant to stimulate your brain. The electrodes pick up the electrical impulses from your brain and send them to the EEG machine, which records your brain waves on a moving sheet of paper. An abnormal EEG result may suggest encephalitis, but a normal result does not rule out the disease. Brain imaging. A computerized tomography (CT) or magnetic resonance imaging (MRI) scan may reveal swelling of your brain. Or it may reveal another condition with signs and symptoms that are similar to

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encephalitis, such as a concussion. If encephalitis is suspected, brain imaging is often done before a spinal tap to look for evidence of elevated intracranial pressure. Brain biopsy. Rarely, if diagnosis of herpes simplex encephalitis isn't possible using DNA methods or by CT or MRI scans, your doctor may take a small sample of your brain tissue. This sample is analyzed in the laboratory to see if the virus is present. Your doctor may also try treatment with antiviral medications before suggesting brain biopsy. Blood testing. Your doctor can confirm the presence of West Nile virus in your body by drawing a sample of your blood for laboratory analysis. If you have West Nile virus, an analysis of your blood sample may show a rising level of an antibody to the virus, a positive DNA test for the virus or a positive culture of the virus.

Complications Severe viral encephalitis can cause respiratory arrest, coma and death. It may also leave marked mental impairment, which can include loss of memory, the inability to speak coherently, lack of muscle coordination, paralysis, or hearing or vision defects.

Treatment Treatment for mild cases mainly consists of rest and a healthy diet, including plenty of liquids, to let your immune system fight the virus. Using acetaminophen (Tylenol, others) can relieve headaches and fever. Antiinflammatory drugs can help reduce swelling and pressure within your skull. If you're having seizures, your doctor may prescribe an anticonvulsant medication. In some cases, you may also need physical and speech therapy. Encephalitis can be difficult to treat because the viruses that cause the disease generally don't respond to medications. However, some viruses, particularly the herpes simplex virus and varicella-zoster virus, respond to antiviral drugs such as acyclovir (Zovirax). If you have one of these kinds of virus-induced encephalitis, your doctor will likely start treatment with acyclovir immediately. Another antiviral that's sometimes used is ganciclovir (Cytovene). Scientists are investigating interferon therapy — a type of immune cell therapy — as a treatment for encephalitis caused by the St. Louis and West Nile viruses. A pilot study of the treatment showed that people who received the therapy recovered better than those who didn't receive the therapy. However, more studies are needed before the treatment can be approved for these illnesses.

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The best way to prevent viral encephalitis is to avoid the viruses that lead to this disease. That means taking steps to prevent genital herpes, for one. It also means making sure you and your children are immunized against chickenpox, measles (rubeola), mumps and rubella (German measles). To protect yourself and your family against mosquito-borne encephalitis during an outbreak of the disease: • •

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Dress to protect yourself. Wear long-sleeved shirts and long pants if you're outside between dusk and dawn. Apply mosquito repellent. The Environmental Protection Agency has found only two products — DEET and picaridin — to be effective at controlling insect bites. When you're going to be outdoors, especially at dawn and dusk when mosquitoes are more active, apply a product containing one of these ingredients to the outside of your clothing and to your exposed skin. Don't spray insect repellant on your face; spray it on your hands and then apply it to your face. Don't use DEET on the hands of young children because they may put their hands in their mouths or eyes. The American Academy of Pediatrics advises parents not to use insect repellants on infants younger than 2 months of age. Instead, cover your infant's stroller or playpen with mosquito netting when outside. Avoid mosquitoes. Refrain from unnecessary activity in places where mosquitoes are most prevalent. Additionally, avoid being outdoors from dusk till dawn whenever possible — that's the time when mosquitoes are most active. Keep mosquitoes out of your home. Repair holes in screens on doors and windows. Get rid of water sources outside your home. Eliminate standing water in your yard, where mosquitoes can lay their eggs. Empty birdbaths, drains, wheelbarrows and flowerpots, and remove old tires and unused containers that might hold water. Drain puddles when possible. Clean your gutters and drain flat roofs regularly. Take advantage of nature's mosquito-controlling creatures. Fill ornamental pools with mosquito-eating fish. Consider placing houses for other mosquito eaters, such as bats, in your yard. Look for outdoor signs of viral disease. If you notice sick or dying birds, report your observations to your local health department.

A vaccine is available to protect horses from West Nile virus. No vaccine is available for humans, but researchers are working to develop one. Encephalitis literally means an inflammation of the brain, but it usually refers to brain inflammation caused by a virus. It's a rare disease that only occurs in approximately 0.5 per 100,000 individuals - most commonly in children, the elderly, and people with weakened immune systems (i.e., those with HIV/AIDS or cancer). 11

Although several thousand cases of encephalitis (also called acute viral encephalitis or aseptic encephalitis) are reported to the Centers for Disease Control and Prevention (CDC) every year, experts suspect that many more may go unreported because the symptoms are so mild.

Signs and Symptoms Symptoms in milder cases of encephalitis usually include: • • • • •

fever headache poor appetite loss of energy just a general sick feeling

In more severe cases of encephalitis, a person is more likely to experience high fever and any of a number of symptoms that relate to the central nervous system including: • • • • • • • • • • • •

severe headache nausea and vomiting stiff neck confusion disorientation personality changes convulsions (seizures) problems with speech or hearing hallucinations memory loss drowsiness coma

It's harder to detect some of these symptoms in infants, but there are still some important signs to look for including: • • • •

vomiting a full or bulging soft spot (fontanel) crying that doesn't stop or that seems worse when an infant is picked up or handled in some way body stiffness

Because encephalitis can follow or accompany common viral illnesses, there are sometimes characteristic signs and symptoms of these illnesses beforehand. But often, the encephalitis appears without warning.

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Causes Because encephalitis can be caused by many types of germs, the infection can be spread in several different ways. Of the many different kinds of viruses that can cause encephalitis, one of the most dangerous and the most common cause of encephalitis is the herpes simplex virus (HSV). HSV is the same virus that causes cold sores around the mouth, but when it attacks the brain it may be fatal in as many as half of newborns who become infected and up to 28% of individuals after the newborn period. Fortunately, HSV encephalitis is very rare. Encephalitis can be a complication of Lyme disease transmitted by ticks, or of rabies spread by rabid animals. Mosquitoes can also transmit the viruses for several types of encephalitis, including West Nile encephalitis, St. Louis encephalitis, and Western Equine encephalitis. Over the last several years in the United States, there's been concern about the spread of West Nile virus, which is transmitted to humans by mosquitoes that pick up the virus by biting infected birds. Milder forms of encephalitis can follow or accompany common childhood illnesses, including measles, mumps, chickenpox, rubella (German measles), and mononucleosis. Viruses like chickenpox spread mostly via the fluids of the nose and throat, usually during a cough or sneeze. Less commonly, encephalitis can result from a bacterial infection, such as bacterial meningitis, or it may be a complication of other infectious diseases like syphilis. Certain parasites, like toxoplasmosis, can also cause encephalitis in people with weakened immune systems.

Contagiousness Brain inflammation itself is not contagious, but any of the various viruses that cause encephalitis can be. Of course, just because a child gets a certain virus does not mean that he or she will develop encephalitis. Still, to be safe, children should avoid with anyone who has encephalitis.

Prevention Encephalitis cannot be prevented except to try to prevent the illnesses that may lead to it. Encephalitis that may be seen with common childhood illnesses like measles, mumps, and chickenpox can be largely prevented through proper immunization. Have your child immunized according to the immunization schedule recommended by your child's doctor. Children should also avoid with anyone who already has encephalitis. 13

In areas where encephalitis can be transmitted by insect bites, especially mosquitoes, children should: • • •

Avoid being outside at dawn and dusk (when mosquitoes are most active). Wear protective clothing like long sleeves and long pants. Use insect repellent.

Also, all standing water around your home should be drained, including buckets, birdbaths, and flowerpots, because these are breeding grounds for mosquitoes. Some things you can do to avoid tick bites: • • •

Limit your child's with soil, leaves, and vegetation. Have your child wear long-sleeved, light-colored shirts and long pants. Check your child and your pets frequently for ticks.

Duration For most forms of encephalitis, the acute phase of the illness (when symptoms are the most severe) usually lasts up to a week. Full recovery can take much longer, often several weeks or months.

Diagnosis Doctors use several tests to diagnose encephalitis, including: •

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imaging tests, such as computed tomography (CT) scans or magnetic resonance imaging (MRI), to check the brain for swelling, bleeding, or other abnormalities electroencephalogram (EEG), which records the electrical signals in the brain, to check for abnormal brain waves blood tests to confirm the presence of bacteria or viruses in the blood, and whether a person is producing antibodies (specific proteins that fight infection) in response to a germ lumbar puncture, also known as a spinal tap, in which cerebrospinal fluid (the fluid that surrounds the brain and spinal cord) is checked for signs of infection

Treatment Some children with very mild encephalitis can be monitored at home, but most will need care in a hospital, usually in an intensive care unit. Doctors will

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carefully monitor their blood pressure, heart rate, and breathing, as well as their body fluids, to prevent further swelling of the brain. Because antibiotics aren't effective against viruses, they aren't used to treat encephalitis. However, antiviral drugs can be used to treat some forms of encephalitis, especially the type caused by the herpes simplex virus. Corticosteroids may also be used in some cases to reduce brain swelling. If a child is having seizures, anticonvulsants may also be given. Over-the-counter (OTC) medications, like acetaminophen, can be used to treat fever and headaches. Most people with encephalitis make a full recovery. In a small percentage of cases, swelling of the brain can lead to permanent brain damage and lasting complications like learning disabilities, speech problems, memory loss, or lack of muscle control. Speech, physical, or occupational therapy may be necessary in these cases. Rarely, if the brain damage is severe, encephalitis can lead to death. Infants younger than 1 year and adults older than 55 are at greatest risk of death from encephalitis.

When to Call Your Child's Doctor Call your child's doctor if your child has a high fever, especially if he or she also has a childhood illness (measles, mumps, chickenpox) or is recovering from one. Seek immediate medical attention if your child has any of the following symptoms: • • • • • • • • • • • • •

severe headache convulsions (seizures) stiff neck inability to look at bright lights double vision difficulty walking problems with speech or hearing difficulty moving an arm or leg loss of sensation anywhere in the body sudden personality changes problems with memory extreme drowsiness or lethargy loss of consciousness

If your infant has any of the following symptoms, seek immediate medical care: 15

• • • • • • • •

high fever or any fever higher than 100.4 degrees Fahrenheit (38 degrees Celsius) in infants younger than 3 months of age fullness or bulging in the soft spot any stiffness floppiness or decreased tone lethargy poor appetite or reduced feeding vomiting crying that won't stop

Encephalitis Encephalitis is an inflammation of the brain. The usual cause is a viral infection, but bacteria can also cause it. Cases can range from mild to severe. For mild cases, you could have flu-like symptoms. Serious cases can cause • • • • • •

Severe headache Sudden fever Drowsiness Vomiting Confusion Seizures

For mild cases, you may just need rest, plenty of fluids and a pain reliever. For severe cases, you might need to be hospitalized. Fortunately, encephalitis is uncommon in the United States. Encephalitis is an inflammation (swelling) of the brain. Encephalitis is usually caused by a virus, but other things, including bacteria, may cause it as well. Although encephalitis sounds scary, most cases aren't serious.

What Is Encephalitis? Encephalitis (pronounced: in-seh-fuh-lye-tus) is typically caused by three different groups of viruses. The herpes viruses is one group, and includes chickenpox, EBV (Epstein-Barr virus — the virus that causes mono), and herpes simplex (the virus that causes cold sores). The second group is made up of viruses and other germs that are transmitted by insects. Viruses like West Nile virus, which is transmitted through a mosquito bite, and the germs that cause Lyme disease and Rocky Mountain spotted fever, which are transmitted thorough tick bites, can also cause encephalitis. The third group is made up of viruses that cause childhood infections that used to be common. These include measles, mumps, and German measles. Because lots of countries immunize against these diseases, it's rarer today that a person will develop encephalitis as a result of an illness like measles or mumps. 16

Some cases of encephalitis are mild and symptoms only last for a short time. However, it is possible to develop a severe case of encephalitis that can be serious and possibly even life threatening. When a person has encephalitis, his or her brain becomes inflamed — inflammation means swelling and irritation.

Is It Contagious? Infection with many different viruses can lead to encephalitis. So how contagious the infection is depends on which virus caused it. Viruses like West Nile are only transmitted through the bite of infected insects; it's not possible to catch them from other people. But viruses like EBV are ed from person to person. Even if a person catches a virus that can cause encephalitis, that does not mean that person will automatically develop the condition. In fact, very few of the people who are infected with these viruses actually develop encephalitis.

What Are the Signs and Symptoms? Encephalitis may cause fever, headache, poor appetite, loss of energy, or just a general sick feeling. In more severe cases, other symptoms might occur, including: • • • • • • • •

high fever severe headache sensitivity to light (called photophobia, which means light hurts your eyes) nausea and vomiting stiff neck confusion sleepiness, difficulty waking, or unconsciousness convulsions (seizures)

When encephalitis happens after a common illness like chickenpox, the signs and symptoms of that illness usually come before symptoms of inflammation in the brain. But encephalitis can also appear without warning. If you have symptoms of encephalitis, get in touch with your doctor right away.

How Is It Diagnosed and Treated? To diagnose encephalitis, the doctor may take blood samples and order a spinal tap (also called a lumbar puncture) to remove some cerebrospinal fluid (CSF) that surrounds the brain and spinal cord for testing. A spinal tap is a procedure that involves inserting a very thin needle into the lower back to take out a small amount of CSF. The blood and CSF will then be sent to a laboratory

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to check for viruses or bacteria. A special brain scan (an MRI or a CT scan) may also be ordered to look for inflammation. A doctor might also order an electroencephalogram (EEG), a test that records your brain waves and can reveal any abnormalities that are consistent with encephalitis. Treatment for encephalitis depends on the virus or other germ that caused it. People with mild cases of encephalitis can recover at home as long as they're watched carefully by a parent or other adult in the household. Most cases of encephalitis just run their course and the person gets better without treatment. Some viruses that cause encephalitis can be treated with medication. For example, acyclovir, an antiviral drug, can help treat encephalitis caused by the herpes simplex virus. In addition, steroid medications can be used to reduce swelling in the brain (these aren't the same as the dangerous performanceenhancing steroids that some athletes use). Because antibiotics are not effective against viruses, they're not used to treat viral encephalitis. Severe cases of encephalitis require a hospital stay so the patient can be carefully monitored and medical treatment is close at hand if needed. For people who have had severe encephalitis that has affected some of the brain's functions, doctors may recommend physical therapy or speech therapy to help with recovery.

How Long Does It Last? The worst symptoms of encephalitis generally last up to 1 week, but full recovery may take weeks or longer. Because encephalitis affects the brain, people with severe cases can sometimes develop problems like seizures, difficulties with muscle coordination, and learning disabilities.

Can I Prevent Encephalitis? The best way to prevent encephalitis is to avoid getting infected with the viruses or other germs that can cause it. Regular hand washing will help limit the spread of some of these germs. Staying as healthy as possible by eating a balanced diet and getting plenty of rest can help keep your immune system in shape. Immunizations are also an important way to protect people from diseases like chickenpox and measles. In areas where viruses are transmitted by insect bites, protect yourself by wearing long sleeves and pants and applying an insect repellent. Also, try to avoid unnecessary outdoor activities at dawn and dusk when mosquitoes are most likely to bite.

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Reviewed by: Steven Dowshen, MD Date reviewed: November 2007 What is meningitis? What is encephalitis?

Infections in the brain and spinal cord can cause dangerous inflammation. This inflammation can produce a wide range of symptoms, including fever, headache, or confusion and, in extreme cases, can cause brain damage, stroke, seizures, or even death. Infection of the meninges, the membranes that surround the brain and spinal cord, is called meningitis and inflammation of the brain itself is called encephalitis. Myelitis is an infection of the spinal cord. When both the brain and the spinal cord become inflamed, the condition is called encephalomyelitis. top What causes meningitis and encephalitis?

Meningitis and encephalitis are usually caused by viruses or bacteria. Most often, the body’s immune system is able to contain and defeat an infection. But if the infection es into the blood stream and then into the cerebrospinal fluid that surrounds the brain and spinal cord, it can affect the nerves and travel to the brain and/or surrounding membranes, causing inflammation. This swelling can harm or destroy nerve cells and cause bleeding in the brain. Meningitis Meningitis is most often caused by a bacterial or viral infection. It also may be caused by a fungal infection, a reaction to certain medications or medical treatments, an inflammatory disease such as lupus, some types of cancer, or a traumatic injury to the head or spine. Bacterial meningitis is a rare but potentially fatal disease. It can be caused by several types of bacteria that first cause an upper respiratory tract infection and then travel through the blood stream to the brain. The disease can also occur when certain bacteria invade the meninges directly. The disease can block blood vessels in the brain, causing stroke and permanent brain damage.

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Pneumococcal meningitis is the most common form of meningitis and is the most serious form of bacterial meningitis. Some 6,000 cases of pneumococcal meningitis are reported in the United States each year. The disease is caused by the bacterium Streptococcus pneumoniae, which also causes pneumonia, blood poisoning (septicemia), and ear and sinus infections. At particular risk are children under age 2 and adults with a weakened or depressed immune system. Persons who have had pneumococcal meningitis often suffer neurological damage ranging from deafness to severe brain damage. Meningococcal meningitis, which is caused by the bacterium Neisseria meningitides, is common in children ages 2-18. Each year in the United States about 2,600 people get this highly contagious disease. High-risk groups include infants under the age of 1 year, people with suppressed immune systems, travelers to foreign countries where the disease is endemic, and college students (freshmen in particular) who reside in dormitories. Between 10 and 15 percent of cases are fatal, with another 10-15 percent causing brain damage and other serious side effects. Haemophilus meningitis was at one time the most common form of bacterial meningitis. Fortunately, the Haemophilus influenzae b vaccine has greatly reduced the number of cases in the United States. Those most at risk of getting this disease are children in child-care settings and children who do not have access to the vaccine. Other forms of bacterial meningitis include Listeria monocytogenes meningitis, which can cross the placental barrier and cause a baby to be stillborn or die shortly after birth; Escherichia coli meningitis, which is most common in elderly adults and newborns and may be transmitted to a baby through the birth canal, and Mycobacterium tuberculosis meningitis, a rare disease that occurs when the bacterium that causes tuberculosis attacks the meninges. Viral, or aseptic, meningitis is the most common form of meningitis in the United States. This typically mild and non-lethal disease is usually caused by enteroviruses—common viruses that enter the body through the mouth and travel to the brain and surrounding tissues where they multiply. Enteroviruses are present in mucus, saliva, and feces and can be transmitted through direct with an infected person or an infected object or surface. Other viruses that cause meningitis include varicella zoster (the virus that causes chicken pox and can appear decades later as shingles), influenza, mumps, HIV, and herpes simplex type 2 (genital herpes). Many fungal infections can affect the brain. The most common form of fungal meningitis is caused by the fungus cryptococcus neoformans (found mainly in dirt and bird droppings). Cryptococcal meningitis is common in AIDS patients. Although treatable, fungal meningitis often recurs in nearly half of affected persons. 20

Encephalitis Encephalitis can be caused by bacterial infection and, most often, viral infections. Several thousand cases of encephalitis are reported each year, but many more may actually occur since the symptoms may be mild to non-existent in most patients. There are two types of encephalitis. Primary encephalitis (also called acute viral encephalitis) is caused by a direct viral infection of the spinal cord and brain. The infection may be focal (located in only one area) or diffuse (located in many different areas). Secondary encephalitis, also known as post-infective encephalitis, can result from complications of a current viral infection. Secondary encephalitis that results from an immunization or earlier viral infection is known as acute disseminated encephalitis. This illness often occurs 2 to 3 weeks following the initial infection. Most cases of encephalitis in the United States are caused by enteroviruses, herpes simplex virus types 1 and 2, a bite from a rabid animal (rabies virus), or arboviruses, which are transmitted from infected animals to humans through the bite of an infected tick, mosquito, or other blood-sucking insect. Lyme disease, a bacterial infection spread by tick bite, can cause encephalitis. Herpes simplex encephalitis (HSE) is responsible for about 10 percent of all encephalitis cases, with a frequency of about 2 cases per million persons per year. More than half of untreated cases are fatal. About 30 percent of cases result from the initial infection with the herpes simplex virus; the majority of cases are caused by reactivation of an earlier infection. HSE due to herpes simplex virus type 1 (which causes cold sores or blisters around the mouth or eyes) can affect any age group but is most often seen in persons under age 20 or over age 40. This rapidly progressing disease is the single most important cause of fatal sporadic encephalitis in the U.S. The virus is transmitted through with an infected person. Symptoms include headache and fever for up to 5 days, followed by personality and behavioral changes, seizures, partial paralysis, hallucinations, and altered levels of consciousness. Brain damage in adults and in children beyond the neonatal period is usually seen in the frontal and temporal lobes and can be severe. Type 2 virus (genital herpes) is most often transmitted through sexual . An infected mother can transmit the disease to her child at birth, through with genital secretions, but this is uncommon. In newborns, symptoms such as lethargy, irritability, tremors, seizures, and poor feeding generally develop between 4 and 11 days after delivery. Powassan encephalitis is the only well-documented tick-borne arbovirus in the United States and Canada. Symptoms are noticed 7-10 days following the bite 21

and may include headache, fever, nausea, confusion, partial paralysis, and coma. Permanent neurologic damage occurs in about half of all cases and death in about 10-15 percent of all cases. Four common forms of mosquito-transmitted viral encephalitis are seen in the United States: •

•

•

•

Equine encephalitis affects horses and humans. Eastern equine encephalitis also infects birds that live in freshwater swamps of the eastern U.S. seaboard and along the Gulf Coast. In humans, symptoms are seen 4-10 days following transmission and include sudden fever, general flu-like muscle pains, and headache of increasing severity, followed by coma and death in severe cases. About half of infected patients die from the disorder. Fewer than 10 human cases are seen annually in the United States. Western equine encephalitis is seen in farming areas in the western and central plains states. Symptoms begin 5-10 days following infection. Children, particularly those under 12 months of age, are affected more severely than adults and may have permanent neurologic damage. Death occurs in about 3 percent of cases. Venezuelan equine encephalitis is very rare in this country. Children are at greatest risk of developing severe complications, while adults generally develop flu-like symptoms. Epidemics in South and Central America have killed thousands of persons and left others with permanent, severe neurologic damage. LaCrosse encephalitis occurs most often in the upper midwestern states (Illinois, Wisconsin, Indiana, Ohio, Minnesota, and Iowa) but also has been reported in the southeastern and mid-Atlantic regions of the country. Most cases are seen in children under age 16. Symptoms such as vomiting, headache, fever, and lethargy appear 5-10 days following infection. Severe complications include seizure, coma, and permanent neurologic damage. About 100 cases of LaCrosse encephalitis are reported each year. St. Louis encephalitis is most prevalent in temperate regions of the United States but can occur throughout most of the country. The disease is generally milder in children than in adults, with elderly adults at highest risk of severe disease or death. Symptoms typically appear 7-10 days following infection and include headache and fever. In more severe cases, confusion and disorientation, tremors, convulsions (especially in the very young), and coma may occur. West Nile encephalitis was first clinically diagnosed in the United States in 1999; 284 people are known to have died of the virus the following year. There were 9,862 reported cases of human West Nile disease in calendar year 2003, with a total of 560 deaths from this disorder over 5 years. The disease is usually transmitted by a bite from an infected mosquito, but can also occur after transplantation of an infected organ or transfusions of infected blood or blood products. Symptoms are flu22

like and include fever, headache, and t pain. Some patients may develop a skin rash and swollen lymph glands, while others may not show any symptoms. At highest risk are elderly adults and people with weakened immune systems. Who is at risk for encephalitis and meningitis? Anyone can get encephalitis or meningitis. People with weakened immune systems, including those persons with HIV or those taking immunosuppressant drugs, are at the highest risk of contracting the diseases. How are these disorders transmitted? Some forms of bacterial meningitis and encephalitis are contagious and can be spread through with saliva, nasal discharge, feces, or respiratory and throat secretions (often spread through kissing, coughing, or sharing drinking glasses, eating utensils, or such personal items as toothbrushes, lipstick, or cigarettes). For example, people sharing a household, at a day care center, or in a classroom with an infected person can become infected. College students living in dormitories—in particular, college freshmen—have a higher risk of contracting meningococcal meningitis than college students overall. Children who do not have access to childhood vaccines are at increased risk of developing certain types of bacterial meningitis. Because these diseases can occur suddenly, anyone who is suspected of having either meningitis or encephalitis should immediately a doctor or go to the hospital. What are the signs and symptoms? The hallmark signs of meningitis are sudden fever, severe headache, and a stiff neck; encephalitis is characterized by seizures, stupor, coma, and related neurological signs. In more severe cases, neurological symptoms may include nausea and vomiting, confusion and disorientation, drowsiness, sensitivity to bright light, and poor appetite. Meningitis often appears with flu-like symptoms that develop over 1-2 days. Distinctive rashes are typically seen in some forms of the disease. Meningococcal meningitis may be associated with kidney and adrenal gland failure and shock. Patients with encephalitis often show mild flu-like symptoms. In more severe cases, patients may experience problems with speech or hearing, double vision, hallucinations, personality changes, loss of consciousness, loss of sensation in some parts of the body, muscle weakness, partial paralysis in the arms and legs, sudden severe dementia, impaired judgment, seizures, and memory loss. 23

Important signs of encephalitis to watch for in an infant include vomiting, body stiffness, constant crying that may become worse when the child is picked up, and a full or bulging fontanel (the soft spot on the top of the head). How are meningitis and encephalitis diagnosed? Following a physical exam and medical history to review activities of the past several days (such as recent exposure to insects or animals, any with ill persons, or recent travel), the doctor may order various diagnostic tests to confirm the presence of infection and inflammation. Early diagnosis is vital, as symptoms can appear suddenly and escalate to brain damage, hearing and/or speech loss, blindness, or even death. A neurological examination involves a series of tests designed to assess motor and sensory function, nerve function, hearing and speech, vision, coordination and balance, mental status, and changes in mood or behavior. Doctors may test the function of the nervous system through tests of strength and sensation, with the aid of items including a tuning fork, small light, reflex hammer, and pins. Laboratory screening of blood, urine, and body secretions can help detect and identify brain and/or spinal cord infection and determine the presence of antibodies and foreign proteins. Such tests can also rule out metabolic conditions that have similar symptoms. For example, a throat culture may be taken to check for viral or bacterial organisms that cause meningitis or encephalitis. In this procedure, the back of the throat is wiped with a sterile cotton swab, which is then placed on a culture medium. Viruses and bacteria are then allowed to grow on the medium. Samples are usually taken in the physician’s office or in a laboratory setting and sent out for analysis to state laboratories or to the U.S. Centers for Disease Control and Prevention. Results are usually available in 2 to 3 days. Analysis of the cerebrospinal fluid that surrounds and protects the brain and spinal cord can detect infections in the brain and/or spinal cord, acute and chronic inflammation, and other diseases. In a procedure known as a spinal tap (or lumbar puncture), a small amount of cerebrospinal fluid is removed by a special needle that is inserted into the lower back. The skin is anesthetized with a local anesthetic prior to the sampling. The fluid, which is completely clear in healthy people, is tested to detect the presence of bacteria or blood, as well as to measure glucose levels (a low glucose level is a sign of bacterial or fungal meningitis) and white blood cells (elevated white blood cell counts are also a sign of infection). The procedure is usually done in a hospital and takes about 45 minutes. Computer-assisted imaging can reveal signs of brain inflammation, internal bleeding or hemorrhage, or other brain abnormalities. Two painless, 24

noninvasive imaging procedures are routinely used to diagnose meningitis and encephalitis. •

•

Computed tomography, also known as a CT scan, combines x-rays and computer technology to produce rapid, clear, two-dimensional images of organs, bones, and tissues. Occasionally a contrast dye is injected into the bloodstream to highlight the different tissues in the brain and to detect signs of encephalitis or inflammation of the meninges. CT scans can also detect bone and blood vessel irregularities, certain brain tumors and cysts, herniated discs, spinal stenosis (narrowing of the spinal canal), blood clots or intracranial bleeding in patients with stroke, brain damage from a head injury, and other disorders. Magnetic resonance imaging (MRI) uses computer-generated radio waves and a strong magnet to produce detailed images of body structures, including tissues, organs, bones, and nerves. The pictures, which are clearer than those produced by CT, can help identify brain and spinal cord inflammation, infection, tumors, eye disease, and blood vessel irregularities that may lead to stroke. A contrast dye may be injected prior to the test to reveal more detail.

Electroencephalography, or EEG, can identify abnormal brain waves by monitoring electrical activity in the brain through the skull. Among its many functions, EEG is used to help diagnose certain seizure disorders, brain damage from head injuries, specific viral infections such as herpes virus, and inflammation of the brain and/or spinal cord. This painless, risk-free test can be performed in a doctor’s office or at a hospital or testing facility. How are these infections treated? Persons who are suspected of having meningitis or encephalitis should receive immediate, aggressive medical treatment. Both diseases can progress quickly and have the potential to cause severe, irreversible neurological damage. Meningitis Early treatment of bacterial meningitis is important to its outcome. Strong doses of general antibiotics may be prescribed first, followed by intravenous antibiotics in more severe cases. Antibiotics may also be given to prevent other bacterial infections. Appropriate antibiotic treatment for most types of meningitis can reduce the risk of dying from the disease to below 15 percent. Infected sinuses may need to be drained. Corticosteroids such as prednisone may be ordered to relieve brain pressure and swelling and to prevent hearing loss that is common in patients with Haemophilus influenza meningitis. Pain medicine and sedatives may be given to make patients more comfortable. Lyme disease is treated with intravenous antibiotics. 25

Unlike bacteria, viruses cannot be killed by antibiotics (an exception is the herpes virus, which can be treated with the antiviral drug acyclovir). Patients with mild viral meningitis may be allowed to stay at home, while those who have a more serious infection may be hospitalized for ive care. Patients with mild cases, which often cause only flu-like symptoms, may be treated with fluids, bed rest (preferably in a quiet, dark room), and analgesics for pain and fever. The physician may prescribe anticonvulsants such as dilantin or phenytoin to prevent seizures and corticosteroids to reduce brain inflammation. If inflammation is severe, pain medicine and sedatives may be prescribed to make the patient more comfortable. Acute disseminated encephalomyelitis is treated with steroids. Fungal meningitis is treated with intravenous antifungal medications. Encephalitis Antiviral drugs used to treat viral encephalitis include acyclovir and ganciclovir. Very mild cases of encephalitis may be monitored at home by the physician and a caregiver. ive care includes fluids, bed rest, and over-the-counter analgesics to reduce fever and headache. More severe cases may require hospitalization. Anticonvulsants may be prescribed to stop or prevent seizures, along with sedatives to calm more severely infected persons and drugs to counter nausea and vomiting. Corticosteroids and intravenous istration of carbohydrate solutions can reduce brain swelling. Patients with breathing difficulties may require artificial respiration. Patients who experience severe brain inflammation may need physical, speech, and occupational therapy once the acute illness is under control. Can meningitis and encephalitis be prevented? Good personal hygiene can reduce the risk of getting the disease from an infected person. Avoid sharing food, utensils, glasses, and other objects with a person who may be exposed to or have the infection. Wash hands often with soap and rinse under running water. Effective vaccines are available to prevent pneumonia, H. influenza, pneumococcal meningitis, and infection with other bacteria that can cause meningococcal meningitis. People who live, work, or go to school with someone who has been diagnosed with bacterial meningitis may be asked to take antibiotics for a few days as a preventive measure.

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To lessen the risk of being bitten by an infected mosquito or other insect, people should limit outdoor activities at night, wear long-sleeved clothing when outdoors, use insect repellents that are most effective for that particular region of the country, and rid lawn and outdoor areas of free-standing pools of water, in which mosquitoes breed. Do not over-apply repellants, particularly on young children and especially infants, as chemicals may be absorbed through the skin. What is the prognosis for these infections? Outcome generally depends on the particular infectious agent involved, the severity of the illness, and how quickly treatment is given. In most cases, people with very mild encephalitis or meningitis can make a full recovery, although the process may be slow. Patients who experience only headache, fever, and stiff neck may recover in 24 weeks. Patients receiving treatment for viral meningitis and encephalitis usually see some relief in 24-48 hours and recovery in about a month. Patients with bacterial meningitis typically show some relief 48-72 hours following initial treatment but are more likely to experience complications caused by the disease. In more serious cases, these diseases can cause hearing and/or speech loss, blindness, permanent brain and nerve damage, behavioral changes, cognitive disabilities, lack of muscle control, seizures, and memory loss. These patients may need long-term therapy, medication, and ive care. What research is being done? The National Institute of Neurological Disorders and Stroke (NINDS), a component of the National Institutes of Health (NIH) within the U.S. Department of Health and Human Services, conducts and s a wide range of research on neurological disorders, including meningitis and encephalitis. Current research efforts include investigating new chemotherapy-based treatment for neoplastic meningitis (caused by cancer) and gaining a better understanding of how the central nervous system responds to inflammation and the role of T cells (blood cells involved in immune system response) in suppressing infection in the brain. Scientists hope to better understand the molecular mechanisms involved in the protection and disruption of the bloodbrain barrier, which could lead to the development of new treatments for several neuroinflammatory diseases such as meningitis and encephalitis. Other scientists hope to define, at a molecular level, how certain viruses overcome the body’s defense mechanism and interact with target host cells. A possible therapeutic approach under investigation involves testing neuroprotective compounds that block the damage that accumulates after the infection and inflammation of meningitis and encephalitis and can lead to potential complications including loss of cognitive function and dementia.

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What is Subacute Sclerosing Panencephalitis? Subacute sclerosing panencephalitis (SSPE) is a chronic persistent infection of the central nervous system caused by an altered form of the measles virus. It affects primarily children and young adults and usually has a progressive downhill course which results in death within a few years in most patients with a 5% chance of spontaneous remission. It can occur anywhere from 2 to 10 years after the original measles illness, and generally results in progressive neurological deterioration due to brain inflammation and nerve cell death. Since the widespread use of the measles vaccine, SSPE has become very rare. However, studies have shown that the incidence of SSPE has remained high in the Middle East and India. Initial symptoms usually include abnormal behavior, irritability, intellectual deterioration, and memory loss which may be followed by involuntary movements and seizures (in the form of myoclonic spasms). Subsequently, the patient develops further mental deterioration, inability to walk, speech impairment with poor comprehension, and difficulty swallowing (dysphagia). Blindness may also result. In the final stages of disease, the patient may remain mute or comatose. The electrical activity of the brain, as recorded by electroencephalogram (EEG), shows progressive changes during the disease which are typical of SSEP and parallel the slow deterioration of central nervous system functions. A number of clinical staging scales have been used for several decades to categorize patients with SSPE according to their corresponding clinical status. More recently, a different staging system was developed based on the radiological findings of the brain by computed tomography (CT) and magnetic resonance imaging (MRI). This method, however, has not succeeded in establishing a complete correlation between radiological abnormalities and clinical progress. Is there any treatment? For several decades, the palliative treatment for SSPE has included anticonvulsant therapy and ive measures (tube feedings and good nursing care especially in patients with advanced disease). Medical literature during the last decade, however, has shown stabilization of disease and delay in clinical progression after therapy with inosine pranobex (oral Isoprinosine); oral isoprinosine combined with intrathecal or intraventricular interferon alpha (up to 50% rate of remission or improvement); oral isoprinosine combined with interferon beta; and intrathecal interferon alpha combined with I.V. ribavirin. However, no controlled studies have been performed. The Food and Drug istration has added inosine pranobex (Isoprinosine) to its List of Orphan Products Designations and Approvals (1988) for the treatment of SSPE. What is the prognosis? When not treated with immunomodulators (interferon) and antivirals (ribavirin and inosine pranobex) SSPE is almost always a fatal disease. Death usually

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occurs between 1 and 3 years after onset, although some spontaneous remissions (up to 5%) have been reported. What research is being done? The NINDS s research on infections and diseases of the brain and nervous system including SSPE. Much of this research is aimed at learning more about the cause(s), prevention, and treatment of these disorders. Currently no clinical trials on SSPE are being conducted at the NIH.

ENCEPHALITIS Background Encephalitis, an inflammation of the brain parenchyma, presents as diffuse and/or focal neuropsychological dysfunction. From an epidemiologic and pathophysiologic perspective, encephalitis is distinct from meningitis, though on clinical evaluation the 2 often coexist with signs and symptoms of meningeal inflammation, such as photophobia, headache, or a stiff neck. Cerebritis describes the stage preceding abscess formation and implies a highly destructive bacterial infection of brain tissue, whereas acute encephalitis is most commonly a viral infection with parenchymal damage varying from mild to profound. Of the subacute and chronic encephalopathies, the ED physician is most likely to encounter toxoplasmosis in immunocompromised patients. No satisfactory treatment exists for the relatively common acute arboviral encephalitides, which vary in epidemiology, mortality, and morbidity, if not clinical presentation. Clinically distinguishing these acute arboviral encephalitides from the 2 potentially treatable acute viral encephalitides is important. The latter encephalitides include herpes simplex encephalitis (HSE), which is a sporadic and lethal disease of neonates and the general population, and the less common varicella-zoster encephalitis, which is deadly in immunocompromised patients Swift identification and immediate treatment can be lifesaving. Most authorities advocate initiating ED treatment with the relatively safe acyclovir in any patient whose CNS presentations (particularly encephalopathy and focal findings) have no apparent explanation and in all neonates who appear ill and are without a final diagnosis. In 1999, a late summer outbreak of West Nile encephalitis (WNE), an arbovirus not found previously in the United States, was implicated in several deaths in

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New York. By late summer 2002, West Nile virus has been identified throughout the eastern and southeastern United States. Following bird migration, the virus is presently extending westward, and by April 2003, virus activity had been detected in 46 states and the District of Columbia. An updated Centers for Disease Control and Prevention (CDC) report for 2007 (West Nile Virus Update) includes information regarding viremic blood donors. Throughout the world, outbreaks of WNE have been associated with severe neurologic disease; though, in general, only 1 in 150 affected patients develop symptomatic WNE. For more information, see the CDC fact sheet on West Nile virus, links to State and Local Government web sites on West Nile virus, and the Environmental Protection Agency (EPA)/CDC article on mosquito control. For clinical information on the Internet, see resources for physicians and interested laypersons provided by Cornell's Environmental Risk Analysis Program. Finally, West Nile Virus: A Primer for the Clinician from the August 6, 2002, issue of the Annals of Internal Medicine is available online in Adobe PDF format. The Canadian equivalent, West Nile Virus: Primer for Family Physicians, was published June 10, 2005 in Canadian Family Physician.

Pathophysiology Portals of entry are virus specific. Many viruses are transmitted by humans, although most cases of HSE are thought to be reactivation of the herpes simplex virus (HSV) lying dormant in the trigeminal ganglia. Mosquitoes or ticks inoculate arbovirus, and rabies virus is transferred via animal bite. With some viruses, such as varicella-zoster virus (VZV) and cytomegalovirus (CMV), an immunocompromised host is a key risk factor. In general, the virus replicates outside the CNS and gains entry either by hematogenous spread or by traveling along neural (rabies, HSV, VZV) and olfactory (HSV) pathways. The etiology of slow virus infections, such as those implicated in the measles-related subacute sclerosing panencephalitis (SSPE) and progressive multifocal leukoencephalopathy (PML), is poorly understood. Once across the blood-brain barrier, the virus enters neural cells, with resultant disruption in cell functioning, perivascular congestion, hemorrhage, and inflammatory response diffusely affecting gray matter disproportionately to white matter. Focal pathology is the result of neuron cell membrane receptors found only in specific portions of the brain and s for regional tropism found with some viruses. For example, HSV has a predilection for the inferior and medial temporal lobes. Although most histologic features are nonspecific, brain biopsies are the diagnostic criterion standard for rabies. Presence of Negri bodies in the hippocampus and cerebellum are pathognomonic of rabies, as are HSV Cowdry 30

type A inclusions with hemorrhagic necrosis in the temporal and orbitofrontal lobes. In contrast to viruses that invade gray matter directly, acute disseminated encephalitis and postinfectious encephalomyelitis (PIE), secondary to measles (most common), Epstein-Barr virus (EBV), and CMV, are immune-mediated processes, which result in multifocal demyelination of perivenous white matter.

Frequency United States Determining the true incidence is impossible because reporting policies are neither standardized nor rigorously enforced. In the United States, several thousand cases of viral encephalitis are reported yearly to the CDC, with an additional 100 cases a year attributed to PIE. This is probably a fraction of the actual number of cases. HSE, the most common cause of sporadic encephalitis in Western countries, is relatively rare; the overall incidence is 0.2 per 100,000 (neonatal HSV infection occurs in 2-3 per 10,000 live births). Arboviruses are the most common causes of episodic encephalitis with reported incidence similar to that of HSV. These statistics may be even more misleading because most people bitten by arbovirus-infected insects do not develop clinical disease, and only 10% develop overt encephalitis. All arboviruses require an insect vector, which is generally present between June and October. The 2 most common arboviruses result in (1) St Louis encephalitis, found throughout the United States but principally in urban areas around the Mississippi River, and (2) the geographically misnamed California virus (in particular, the strain that causes LaCross encephalitis [LAC]), which affects children in rural areas in states of the northern Midwest and East. Among the other arboviruses causing encephalitis, the deadliest and, fortunately, most uncommon, eastern equine encephalitis (EEE), is encountered in New England and surrounding areas; the milder western equine encephalitis (WEE) is most common in rural communities west of the Mississippi River. Powassan virus is the only well-documented arbovirus transmitted by ticks. Among less common causes of viral encephalitis, varicella-zoster encephalitis has an incidence of 1 in 2000 infected persons. Measles produces 2 devastating forms of encephalitis: postinfectious, which occurs in about 1 in 1000 infected

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persons, and SSPE, occurring in about 1 in 100,000 infected patients. Typically, 0-3 unrelated cases of rabies encephalitis are identified yearly. International Japanese virus encephalitis (JE), occurring principally in Japan, Southeast Asia, China, and India, is the most common viral encephalitis outside the United States.

Mortality/Morbidity Mortality and morbidity are related to host factors, such as preexisting CNS injury and the virulence of infecting organism. Poor outcomes can be anticipated in infants younger than 1 year and adults older than 55 years. •

•

•

Untreated HSE has a mortality rate of 50-75%, virtually 100% of survivors have long-term motor and mental disabilities. Treated HSE correlates strongly with severity of illness at the time of medical intervention, and morbidity is usually quoted at approximately 20%. Arboviral JE and EEE are equally as catastrophic as untreated HSE, but other arboviruses are associated with a more benign clinical course. For example, St Louis encephalitis and WNE have a mortality rate of 2-20%, and death rates from WEE and LAC are less than 5%. The incidence of neurologic sequelae is around 25% but highly variable. The mortality rate associated with PIE secondary to measles approaches 40%, with a high rate of neurologic sequelae in survivors. SSPE is universally fatal, although the disease course may last anywhere from several weeks to 10 years. VZV encephalitis has a mortality rate of 15% in immunocompetent patients and virtually 100% in immunosuppressed patients. The mortality rate for EBV encephalitis is 8%, and the morbidity rate is 12%. Rabies encephalitis and acute disseminated encephalitis are virtually 100% fatal, though the medical literature includes reports of survivors.

Sex Individuals at the extremes of age are at highest risk, particularly for HSE.

Age Individuals at the extremes of age are at highest risk, particularly for HSE. •

Neonatal HSE is a manifestation of disseminated infection (type 1 or 2). Older infants, children, and adults succumb to localized CNS infection

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•

•

(almost exclusively type 1) according to a bimodal pattern of 5-30 years and older than 50 years. St Louis encephalitis and WNE are more common and are most severe in patients older than 60 years. Conversely, LAC is more common and is most severe in children younger than 16 years. EEE and WEE disproportionately affect infants; EEE disproportionately affects children and elderly persons.

History • • •

Clinical presentation and course can be markedly variable. Acuity and severity of presentation correlates with prognosis. The patient may have history of animal bite for which antirabies treatment may not have been obtained. The general viral prodrome is several days long and consists of fever, headache, nausea and vomiting, lethargy, and myalgias. • o

•

The specific prodrome in VZV, EBV, CMV, measles, and mumps includes rash, lymphadenopathy, hepatosplenomegaly, and parotid enlargement. o Dysuria and pyuria are reported with St Louis encephalitis. o Extreme lethargy has been noted with WNE The classic presentation is encephalopathy with diffuse or focal neurologic symptoms, including the following: • o

• •

Behavioral and personality changes, decreased level of consciousness o Stiff neck, photophobia, and lethargy o Generalized or localized seizures (60% of children with California encephalitis [CE]) o Acute confusion or amnestic states o Flaccid paralysis (10% with WNE) Less common symptoms include headache and other complaints of meningismus. Neonatal HSV infection symptoms (1-45 d) may occur in any combination. • o o

•

Skin, eye, and mouth lesions (early presentation) Encephalitis - Change in level of alertness, irritability, seizures, poor feeding o Evidence of widespread, disseminated disease, such as rash or shock HSE in older children and adults • o

Unrelated to history of oral lesions in infants

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Acute onset of severe symptoms of encephalitis Toxoplasma encephalopathy s for as many as 40% of patients who are HIV positive with neurologic disease who present with a subacute headache, encephalopathy, and, often, a focal neurological complaint. This may be the presenting symptom of immunosuppression/HIV infection. o

•

Physical Look for ing evidence of viral infection. •

The signs of encephalitis may be diffuse or focal (80% of patients with HSE present with focal findings) as follows: • o o

•

Altered mental status and/or personality changes (most common) Focal findings, such as hemiparesis, focal seizures, and autonomic dysfunction o Movement disorders (St Louis encephalitis, EEE, WEE) o Ataxia o Cranial nerve defects o Dysphagia (Rabies may for foaming at the mouth and hydrophobia.) o Meningismus (less common and less pronounced than in meningitis) o Unilateral sensorimotor dysfunction (PIE) HSV infection in the neonate (aged 1-45 d) • o

•

Herpetic skin lesions over the presenting surface from birth or with breaks in the skin, such as those resulting from fetal scalp monitors o Keratoconjunctivitis o Oropharyngeal involvement, particularly buccal mucosa and tongue o Encephalitis symptoms, such as seizures, irritability, change in level of attentiveness, bulging fontanels o Additional signs of disseminated HSV, such as shock, jaundice, and hepatomegaly Toxoplasma encephalopathy: In immunosuppressed patients, 75% present with a focal neuropathology, about one half with encephalopathic changes.

Causes

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•

•

The etiology of encephalitis is usually infectious, but may be noninfectious, such as the demyelinating process in acute disseminated encephalitis. Infectious etiologies: Viral agents, such as HSV type 1 and 2 (almost exclusively in neonates), VZV, EBV, measles virus (PIE and SSPE), mumps, and rubella are spread through person-to-person . • o

•

Important animal vectors include mosquitoes, ticks (arbovirus), and warm-blooded mammals (rabies, lymphocytic choriomeningitis). o Bacterial pathogens, such as Mycoplasma species and those causing rickettsial or catscratch disease, are rare and invariably involve inflammation of the meninges out of proportion to their encephalitic components. o Encephalitis due to parasites and fungi other than Toxoplasma gondii is beyond the scope of this article. The CDC confirmed that West Nile virus can be transmitted by means of an organ transplant and via blood transfusions.

Brain Abscess Catscratch Disease Herpes Simplex Herpes Simplex Encephalitis Hypoglycemia Leptospirosis in Humans Meningitis Pediatrics, Meningitis and Encephalitis Status Epilepticus Subarachnoid Hemorrhage Systemic Lupus Erythematosus Tick-Borne Diseases, Lyme Tick-Borne Diseases, Rocky Mountain Spotted Fever Toxoplasmosis Tuberculosis

Other Problems to be Considered Acute CNS events, such as hemorrhagic stroke Acute confusional states secondary to drugs, toxins, psychosis Amoeba (Naegleria, Acanthamoeba) Head trauma CNS syphilis Ehrlichiosis Intracranial hemorrhage Intracranial tumor Trauma 35

Lab Studies • •

•

• •

• • •

Complete blood count (CBC) with differential: Findings are usually within the reference range. Serum electrolytes: These are usually within the reference range. Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) occurs in 25% of patients with St Louis encephalitis.) Serum glucose level: Use this level as a baseline for determining normal CSF glucose values. The result may be low if glycogen stores are depleted or high in infected patients with diabetes mellitus. BUN/creatinine and liver function tests (LFTs): Assess organ function and the need to adjust the antibiotic dose. Platelet test and a coagulation profile: These are indicated in patients with chronic alcohol use, liver disease, or if disseminated intravascular coagulation (DIC) is suspected. The patient may require platelets or fresh-frozen plasma (FFP) before lumbar puncture (LP). Urinary electrolyte test: Perform this assessment if SIADH is suspected. Urine and/or serum toxicology screening: Perform 1 or both of these tests, if indicated. Other laboratory tests • o

o o

o o o

CSF polymerase chain reaction (PCR): A PCR for DNA HSV is 100% specific and 75-98% sensitive within the first 25-45 hours. Types 1 and 2 cross-react, but no cross-reactivity with other herpes viruses occurs. Arguably, a series of quantitative PCRs documenting the decline of viral load with acyclovir treatment may clinch diagnosis without brain biopsy. HSV cultures: These are used to test lesions (also Tzanck smear), CSF (rarely positive), and blood. Viral serology: Complement fixation antibodies are useful in identifying arbovirus. Cross-reactivity exists among one subgroup of arboviruses, the flaviviruses (eg, St Louis encephalitis, JE, WNE), and with antibodies raised in persons inoculated with the yellow fever vaccine. Viral serology: Complement fixation antibodies are useful in identifying arbovirus. Heterophile antibody and cold agglutinins for EBV: These tests may be helpful. Serologic tests for toxoplasmosis: These can be helpful in light of an abnormal CT scan, particularly in the case of single lesions. However, the overlap in titer between previously exposed but presently uninfected and reactivated groups may complicate interpretation.

Imaging Studies

36

Perform head CT, with and without contrast agent, in virtually all patients with encephalitis before LP to search for evidence of elevated intracerebral pressure (I), obstructive hydrocephalus, or mass effect. It is helpful also in differential diagnosis. MRI is more likely to show abnormalities earlier in disease course than head CT. In HSE, an MRI may show several foci of increased T2 signal intensity in medial temporal lobes and inferior frontal gray matter. Head CT may show petechial hemorrhage in the same areas. EEE and tick-borne encephalitis may show similar increased signal intensity in the basal ganglia and thalami. In toxoplasmosis, contrast-enhanced head CT typically reveals several nodular or ring-enhancing lesions. Because lesions may be missed without contrast, MRI should be performed in patients for whom use of contrast material is contraindicated.

•

•

• •

Other Tests Electroencephalography

•

• o

In HSE, characteristic paroxysmal lateral epileptiform discharges (PLEDs) often are observed, even before neuroradiographic changes. o Eventually, PLEDs are positive in 80% of cases. The presence of PLEDs is not pathognomonic for HSE. CSF analysis is essential.

•

• o

o

General patterns in bacterial and fungal (cryptococcal) meningitis found during the measurement of CSF pressure and CSF analysis may a diagnosis (see the Table below). The most important diagnostic test in the ED to rule out bacterial meningitis is well-performed Gram staining and, if available, polymerase chain reaction of the CSF in patients with suspected HSV encephalitis. CSF Findings by Type of Organism

CSF Finding (Normal) Pressure (5-15 cm H2O)

Bacterial Meningitis 

Viral Meningitis* Increased



Normal or mildly increased

Fungal Meningitis 

 

Normal or mildly increased in tuberculosis (TB) May be increased Patients with AIDS and cryptococcal meningitis at increased risk

37

of blindness and death unless pressure maintained at <30 cm

Cell counts, mononuclear cells/mm3 Preterm (0-25) Term (0-22) 6 mo+ (0-5)

 







Microorganisms (none)

No cell count excludes bacterial meningitis Typically thousands of polymorphonuclear cells, but counts may not change dramatically or even be normal (classically in very early meningococcal meningitis or in extremely ill neonates) Lymphocytosis with normal CSF chemistry results observed in 15-25% of patients, especially if counts <1000 or if patient is partially treated About <90% of patients with ventriculoperitoneal shunts and CSF WBC count >100 cells/mm3 are infected; CSF glucose level usually normal, and these patients' pathogens are less pathogenic than others' Cell count and chemistry levels normalize slowly (days) with antibiotics

 80% effective 



Gram stain Inadequate decolorization may cause Haemophilus influenzae to be mistaken for gram-positive cocci Pretreatment with antibiotics may affect stain uptake, causing grampositive species to appear to be gram-negative and decrease culture yield by an average of 20

 





Usually <500, nearly 100% mononuclear <48 hours, clinically significant polymorphonuclear pleocytosis may be indistinguishable from early bacterial meningitis, particularly with EEE Nontraumatic RBCs in 80% of patients with HSV meningoencephalitis, though 10% have normal CSF results

No organism



100s of mononuclear cells



India ink 80-90% effective for detecting fungi Acid-fast bacillus (AFB) stain 40% effective for TB; increase yield by staining supernatant from at least 5 mL of CSF



38

Glucose† Euglycemia (>50% serum) Hyperglycemia (>30% serum)



Protein Preterm (65150 mg/dL) Term (20-170 mg/dL 6 mo+ (15-45 mg/dL)



Decreased

Normal



Sometimes

 decreased

Usually >150 mg/dL

increased May be >1000



Mildly



mg/dL



Aside from fulminant bacterial meningitis, TB, primary amebic meningoencephalitis, and neurocysticercosis cause lowest glucose levels



Increased >1000 mg/dL, with relatively benign clinical presentation suggestive of fungal disease

*Some bacteria (eg, Mycoplasma, Listeria, Leptospira, Borrelia burgdorferi [Lyme disease]) cause alterations in spinal fluid that resemble the viral profile. An aseptic profile is also typical of partially treated bacterial infections (>33%, especially those in children, are treated with antimicrobials) and of the 2 most common causes of encephalitis—the arboviruses and the potentially curable HSV. † Wait 4 h after glucose load.

Procedures •

Brain biopsy is the criterion standard because of its 96% sensitivity and 100% specificity.

TREATMENT Prehospital Care • • • •

Evaluate and treat for shock or hypotension. ister a crystalloid infusion until the patient is euvolemic. Consider airway protection in patients with an altered mental status. Consider seizure precautions. Treat seizures according to usual protocol (ie, lorazepam 0.1 mg/kg given intravenously [IV]). Stabilize alert patients with normal vital signs by istering oxygen, securing IV access, and providing rapid transport to the ED.

Emergency Department Care With the important exceptions of HSE and varicella-zoster encephalitis, the viral encephalitides are not treatable beyond ive care. Treatments for 39

T gondii and CMV encephalitis are available but generally not initiated in the ED. •

The goal of treatment for acutely ill patients is istration of the first dose or doses acyclovir with or without antibiotics or steroids as quickly as possible. • o

•

•

The standard for acute bacterial meningitis is the initiation of treatment within 30 minutes of arrival. o Consider instituting an ED triage protocol to identify patients at risk for HSE. Collect laboratory samples and blood cultures before the start of IV therapy. Even in uncomplicated cases of encephalitis, most authorities recommend a neuroimaging study (eg, contrast-enhanced head CT scan) before LP. Signs of hydrocephalus and increased I • o

•

•

•

General measures: Manage fever and pain, control straining and coughing, and avoid seizures and systemic hypotension. o In otherwise stable patients, elevating the head and monitoring neurologic status usually are sufficient. o When more aggressive maneuvers are indicated, some authorities favor the early use of diuresis (eg, furosemide 20 mg IV, mannitol 1 g/kg IV) provided circulatory volume is protected. Dexamethasone 10 mg IV q6h helps in managing edema surrounding space-occupying lesions. Hyperventilation (PaCO2 30 mm Hg) may cause a disproportional decrease in cerebral blood flow (CBF), but it is used to control increasing I on an emergency basis. o Intraventricular I monitoring is controversial because some authorities believe dangerous focal edema with a pressure gradient between the temporal lobe and the subtentorial space usually is not detected by the monitor, leading to a false sense of security. In fact, monitor placement may potentially aggravate a pressure gradient. Look for and treat systemic complications, particularly in HSE, EEE, JE, such as hypotension or shock, hypoxemia, hyponatremia (SIADH), and exacerbation of chronic diseases. Empiric adult emergency treatment for HSV meningoencephalitis and VZV encephalitis is acyclovir 10 mg/kg (infuse over 1 h) q8h for 14-21 days. Give acyclovir 10-15 mg/kg IV q8h for neonatal HSV; for HSV encephalitis in the pediatric population, give acyclovir 10 mg/kg IV q8h. In HIV-positive patients, consider foscarnet, given increased incidence of acyclovir-resistant HSV and HZV.

Consultations 40

• • • •

Neurosurgeon, if brain biopsy is indicated Neurologist Neonatologist, if indicated Infectious disease specialist, if indicated

MEDICATION The goals of pharmacotherapy are to reduce morbidity and prevent complications. Drug Category: Antivirals The goal of the use of antivirals for HSE and varicella-zoster encephalitis is to shorten the clinical course, prevent complications, prevent the development of latency and/or subsequent recurrences, decrease transmission, and eliminate established latency. Drug Name

Acyclovir (Zovirax)

Description

Has demonstrated inhibitory activity directed against both HSV-1 and HSV-2, and infected cells selectively take it up.

Adult Dose

10 mg/kg (infuse over 1 h) IV q8h for 1421 d

Pediatric Dose

Neonatal HSV: 10-15 mg/kg IV q8h HSV encephalitis: 10 mg/kg IV q8h

Contraindications

Documented hypersensitivity to acyclovir or related products

Interactions

Coistration of probenecid, zidovudine, or other nephrotoxic drugs may prolong the half-life, increasing the CNS toxicity of acyclovir

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Adjust dose according to CrCl; caution in renal failure or coistration of other nephrotoxic drugs

Drug Name

Foscarnet (Foscavir)

Description

Organic analog of inorganic pyrophosphate. Inhibits replication of

41

known herpes viruses, including CMV, HSV-1, and HSV-2. Exerts antiviral activity by inhibiting viral replication at pyrophosphate-binding site on virusspecific DNA polymerases at concentrations that do not affect cellular DNA polymerases. Patients with poor clinical response or experience persistent viral excretion during therapy, especially HIV-positive patients, may be resistant to acyclovir. Patients who tolerate foscarnet may benefit maintenance-level istration of 120 mg/kg/d early in treatment. Dosing should be individualized to patient's renal function. Adult Dose Pediatric Dose

40 mg/kg IV q8h for 14-26 d <12 years: Not established >12 years: ister as in adults

Contraindications Documented hypersensitivity

Interactions

Pregnancy Precautions

Because of tendency to cause renal impairment, avoid use in combination with potentially nephrotoxic drugs (eg, aminoglycosides, amphotericin B, IV pentamidine) unless the potential benefits outweigh risks; avoid use with fluoroquinolones; coistration with IV pentamidine may cause hypocalcemia C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus Renal function may decline; to ensure correct dosing, a 24-h serum creatinine level should be determined at baseline and periodically thereafter; discontinue if serum creatinine <0.4 mL/min/kg; hydration may reduce risks of nephrotoxicity; because of propensity to chelate divalent metal ions and alter serum electrolyte levels, carefully monitor electrolytes, including Ca and Mg; as soon as possible, assess for

42

electrolyte abnormalities and mineral levels in patients with mild perioral numbness, paresthesias, or severe symptoms (eg, seizures); to permit rapid dilution and distribution and to avoid local irritation, infuse solution only into veins with adequate blood flow; relatively high incidence of granulocytopenia and anemia; important to monitor CBCs regularly; do not ister by rapid or bolus IV injection; toxicity may be increased as a result of excessive plasma levels Drug Category: Corticosteroids Anti-inflammatory agents used for treatment of postinfectious encephalitis and acute disseminated encephalitis. These drugs are commonly presented as treatment alternatives, though ing data are limited. Drug Name

Dexamethasone (Decadron, Dexasone)

Description

Used to treat various allergic and inflammatory diseases. May decrease inflammation by suppressing migration of polymorphonuclear leukocytes and reversing increased capillary permeability.

Adult Dose

10 mg IV q6h

Pediatric Dose Contraindications Interactions

Pregnancy Precautions

0.15 mg/kg IV q6h Documented hypersensitivity, active infection, fungal infection Barbiturates, phenytoin, and rifampin can decrease effects; decreases effect of salicylates and vaccines C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus Monitor for adrenal insufficiency when drug is tapered; patients receiving glucocorticoids are at risk for multiple complications, including severe

43

infections; abrupt discontinuation may cause adrenal crisis; hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression, and infections are possible complications

FOLLOW-UP Section 8 of 10 • Authors and Editors • Introduction • Clinical • Differentials • Workup • Treatment • Medication • Follow-up • Miscellaneous • References

�

Further Inpatient Care • •

it the patient to a unit or floor, as appropriate. The itting physician should arrange for EEG, brain biopsy (for HSE), and other advanced measures as indicated.

Deterrence/Prevention •

•

During summer and fall months, emergency physicians should not hesitate to obtain viral cultures to check for outbreaks of arboviral infection. Public health measures, such as insecticide spraying, may be necessary. Immunization against JE is recommended for those traveling into endemic areas during high-risk times of year.

Complications

44

• • • •

Seizures Syndrome of inappropriate secretion of antidiuretic hormone Increased I Coma

Prognosis •

The prognosis depends the virulence of the virus and on variables associated with the patient's health status, such as extremes of age, immune status, and preexisting neurologic conditions. • o

o

o

o

o

Rabies, EEE, JE, and untreated HSE have high rates of mortality and severe morbidity, including mental retardation, hemiplegia, and seizures. Increased mortality and morbidity rates are found in patients who are older than 60 years and have St Louis encephalitis or WNE. Long-term sequelae with St Louis encephalitis include behavioral disorders, memory loss, and seizures. WEE is associated with relatively low mortality and morbidity rates, although developmental delay, seizure disorder, and paralysis occur in children, and postencephalitic parkinsonism occurs in adults. CE usually is a milder disease, with most patients making a full recovery, though 25% of those with severe disease continue to have focal neurologic dysfunction. The mortality rate in treated HSE averages 20% and is correlated with mental status changes at time of first dose of acyclovir. Approximately 40% of survivors have minor-to-major learning disabilities, memory impairment, neuropsychiatric abnormalities, epilepsy, fine-motor-control deficits, and dysarthria.

Patient Education •

For patient education resources, visit eMedicine's Brain and Nervous System Center and Bacterial and Viral Infections Center. Also, see eMedicine's patient education articles Brain Infection, West Nile Virus, Encephalitis, and Ticks.

MISCELLANEOUS Section 9 of 10 • Authors and Editors • Introduction

�

45

• • • • • • • •

Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous References

Medical/Legal Pitfalls •

Failure to consider HSE in the diagnosis or to initiate istration of acyclovir in a timely fashion

46