Encephalitis | |
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MRI scan image shows high signal in the temporal lobes and right inferior frontal gyrus in someone with herpes simplex encephalitis. | |
Specialty | Neurology, infectious disease |
Symptoms | Headache, fever, confusion, stiff neck, vomiting[1] |
Complications | Seizures, trouble speaking, memory problems, problems hearing[1] |
Duration | Weeks to months for recovery[1] |
Types | Herpes simplex, West Nile, rabies, Eastern equine, others[2] |
Causes | Infection, autoimmune, certain medication, unknown[2] |
Diagnostic method | Based on symptoms, supported by blood tests, medical imaging, analysis of cerebrospinal fluid[2] |
Treatment | Antiviral medication, anticonvulsants, corticosteroids, artificial respiration[1] |
Prognosis | Variable[1] |
Frequency | 4.3 million (2015)[3] |
Deaths | 150,000 (2015)[4] |
Encephalitis is inflammation of the brain.[5] The severity can be variable with symptoms including reduction or alteration in consciousness, headache, fever, confusion, a stiff neck, and vomiting.[1][6] Complications may include seizures, hallucinations, trouble speaking, memory problems, and problems with hearing.[1]
Causes of encephalitis include viruses such as herpes simplex virus and rabies virus as well as bacteria, fungi, or parasites.[1][2] Other causes include autoimmune diseases and certain medications.[2] In many cases the cause remains unknown.[2] Risk factors include a weak immune system.[2] Diagnosis is typically based on symptoms and supported by blood tests, medical imaging, and analysis of cerebrospinal fluid.[2]
Certain types are preventable with vaccines.[5] Treatment may include antiviral medications (such as acyclovir), anticonvulsants, and corticosteroids.[1] Treatment generally takes place in hospital.[1] Some people require artificial respiration.[1] Once the immediate problem is under control, rehabilitation may be required.[2] In 2015, encephalitis was estimated to have affected 4.3 million people and resulted in 150,000 deaths worldwide.[3][4]