, Encephalitis is an acute
inflammationof the brain, commonly caused by a viral infection. It can be caused by a bacterial infection such as bacterial meningitisspreading directly to the brain (primary encephalitis), or may be a complication of a current infectious disease like rabiesor syphilis(secondary encephalitis). Certain parasiticor protozoal infestations, such as toxoplasmosis, malaria, or primary amoebic meningoencephalitis, can also cause encephalitis in people with compromised immune systems. Lyme diseasemay also cause encephalitis. Bartonella henselae can also lead to this. Brain damage occurs as the inflamed brain pushes against the skull, and can lead to death.
Patients with encephalitis suffer from fever, headache and
photophobiawith 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.
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 virus, St. Louis Encephalitis, Equine Encephalitis, La Crosse encephalitis, Murray Valley encephalitis virus, California encephalitis virus, Tick-borne meningoencephalitis, Herpes simplex, Influenza A virus. Less common are e.g. RSSE (Russian spring-summer encephalitis [cite journal |author=Kurane I, Takasaki T, Yamada K |title=Trends in flavivirus infections in Japan |journal=Emerging Infect. Dis. |volume=6 |issue=6 |pages=569–71 |year=2000 |pmid=11076713 |doi= |url=http://www.medscape.com/viewarticle/414787_3] ) viruses.
Adult patients with encephalitis present with acute onset of fever, headache, confusion, and sometimes seizures. Younger children or infants may present 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 fluidobtained by a lumbar punctureprocedure usually reveals increased amounts of protein and white blood cells with normal glucose, though in a significant percentage of patients, the cerebrospinal fluid may be 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 simplextype 1 encephalitis. Magnetic resonance imagingoffers 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 reactionthat amplifies the RNAor DNAof the virus responsible (such as varicella zoster virus).
Treatment is usually
symptomatic. Reliably tested specific antiviral agents are available only for a few viral agents (e.g. acyclovirfor herpes simplex virus) and are used with limited success for most infection except herpes simplex encephalitis. In patients who are very sick, supportive treatment, such as mechanical ventilation, is equally important.
Encephalitis lethargicais an atypical form of encephalitis which caused an epidemicfrom 1917 to 1928, resulting in millions of deaths worldwide. Those who survived sank into a semi-conscious state that lasted for decades until the Parkinsons drug L-dopa was used to revive those still alive in the late 1960s by Oliver Sacks.
There have been only a small number of isolated cases in the years 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.
Herpes simplex encephalitis
Herpes simplex encephalitisis caused by the herpes simplex virus that manifests in oral cold sores or genital sores. When this triggers brain inflammation, which occurs in 10% of cases of encephalitis (2 cases per million people), half of all untreated patients die (1 case per million people). Brain damage, partial paralysis, seizures, hallucinations and an altered state of consciousness are all common symptoms. HSE can be passed from mother to child during birth in rare cases, where symptoms include lethargy, tremors, irritability, seizures and poor feeding in the first two weeks after birth.
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 autonomicfunctions).
Granulomatous amoebic encephalitis
St. Louis Encephalitis
La Crosse encephalitis
Murray Valley encephalitis virus
California encephalitis virus
* http://www.encephalitis.info resource providing evidence based support to people affected and professionals
* [http://www.who.int/health_topics/encephalitis/en/ WHO: Encephalitis]
* [http://www.emedicinehealth.com/articles/17223-1.asp eMedicine-1 ] and [http://www.emedicinehealth.com/articles/17223-2.asp eMedicine-2] Information on the causes, symptoms, and treatment options for Encephalitis.
* [http://www.encephalitisglobal.org Encephalitis Global, Inc.] Website offering information and support to encephalitis survivors, caregivers and loved ones. Encephalitis Global Inc. is a USA 501(c)(3) public charity; annual FACES Encephalitis Conference information available at the website.
* [http://www.uiowa.edu/~c064s01/nr059.htm A case study of a Limbic Encephalitis patient]
* [http://www.garrettmtaylor.com/ A website about Garrett Taylor a 2 year old who lost his life after a battle with encephalitis]
*NINDS|encephalitis_meningitis|Meningitis and Encephalitis Information Page
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