Encephalitis (from Ancient Greek , enkphalos brain,[1] composed of , en, in and , kephal, head, and the medical suffix -itis inflammation) is an acute inflammation of the brain.[2] Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue. Further symptoms include seizures or convulsions, tremors, hallucinations, stroke, and memory problems.[3] In 2013 encephalitis was estimated to have resulted in 77,000 deaths, down from 92,000 in 1990.[4]

Adult patients with encephalitis present with acute onset of fever, headache, confusion, and sometimes seizures. Younger children or infants may present irritability, poor appetite and fever.[5] 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 meningoencephalitis.[6]

Viral encephalitis can occur either as a direct effect of an acute infection, or as one of the sequelae of a latent infection. The most common causes of acute viral encephalitis are rabies virus, HPV infection, poliovirus, and measles virus.[7] Other possible viral causes are arbovirus (St. Louis encephalitis, West Nile encephalitis virus), bunyavirus (La Crosse strain), arenavirus (lymphocytic choriomeningitis virus) and reovirus (Colorado tick virus)[8]

It can be caused by a bacterial infection, such as bacterial meningitis,[9] or may be a complication of a current infectious disease syphilis (secondary encephalitis).[10] Certain parasitic or protozoal infestations, such as toxoplasmosis, malaria, or primary amoebic meningoencephalitis, can also cause encephalitis in people with compromised immune systems. Lyme disease and/or Bartonella henselae may also cause encephalitis.[citation needed] Other bacterial pathogens, like Mycoplasma and those causing rickettsial disease, cause inflammation of the meninges and consequently encephalitis. A non-infectious cause includes acute disseminated encephalitis which is demyelinated.[11]

Limbic encephalitis is a system onset indicated by cognitive decrease, especially memory decline as a result of the involvement of the limbic system, MRI evidence indicates particularly the hippocampus. A close depiction can result from autoimmune pathologies.[12]

Autoimmune encephalitis signs are catatonia, psychosis, abnormal movements, and autonomic dysregulation. Anti-N-methyl-D-aspartate encephalitis and Rasmussen encephalitis are examples of autoimmune encephalitis; the fact that these are immune mediate changes to the treatment path.[13]

Encephalitis lethargica is identified by high fever, headache, delayed physical response, and lethargy. Individuals can exhibit upper body weakness, muscular pains, and tremors, though the cause of encephalitis lethargica is not currently known. From 1917 to 1928, an epidemic of encephalitis lethargica occurred worldwide.[14]

Diagnosing encephalitis is done via a variety of tests:[15]

Treatment (which is based on supportive care) is as follows:[16]

Vaccination is available against tick-borne[17] and Japanese encephalitis[18] and should be considered for at-risk individuals. Post-infectious encephalomyelitis complicating smallpox vaccination is avoidable as smallpox is now eradicated. Contraindication to Pertussis immunisation should be observed in patients with encephalitis.[19]

The incidence of acute encephalitis in Western countries is 7.4 cases per 100,000 population per year. In tropical countries, the incidence is 6.34 per 100,000 per year.[20] In 2013 encephalitis was estimated to have resulted in 77,000 deaths, down from 92,000 in 1990.[4] Herpes simplex encephalitis has an incidence of 24 per million population per year.[21]

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Encephalitis - Wikipedia, the free encyclopedia

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