The first symptom of<unk>  is usually rapidly progressive dementia, leading to memory loss, personality changes, and hallucinations. Myoclonus (jerky movements) typically occurs in 90% of cases, but may be absent at initial onset. Other frequently occurring features include anxiety, depression, paranoia, obsessive-compulsive symptoms, and psychosis. This is accompanied by physical problems such as speech impairment, balance and coordination dysfunction (ataxia), changes in gait, and rigid posture. In most people with<unk> , these symptoms are accompanied by involuntary movements. The duration of the disease varies greatly, but sporadic (non-inherited)<unk>  can be fatal within months or even weeks. Most victims die six months after initial symptoms appear, often of pneumonia due to impaired coughing reflexes. About 15% of people with<unk>  survive for two or more years. The symptoms of<unk>  are caused by the progressive death of the brain's nerve cells, which are associated with the build-up of abnormal prion proteins forming in the brain. When brain tissue from a person with<unk>  is examined under a microscope, many tiny holes can be seen where the nerve cells have died. Parts of the brain may resemble a sponge where the prions were infecting the areas of the brain.
Creutzfeldt–Jakob disease
Anti-Hu associated encephalitis
Powassan encephalitis
Kuru (disease)  Kuru  1
Saint Louis encephalitis
Variant Creutzfeldt–Jakob disease  Variant Creutzfeldt–Jakob disease  1
Autoimmune encephalitis
Viliuisk encephalomyelitis