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