Encephalitis is inflammation of the brain. The inflammation is caused either by an infection invading the brain (infectious); or through the immune system attacking the brain in error (post-infectious / autoimmune encephalitis).
Nerve cells may be damaged or destroyed by the viral infection, the immune reaction and by pressure resulting from the inflammation. This damage is termed “acquired brain injury (ABI). Some loss of brain function is therefore a probable outcome of encephalitis. In some cases, however, this loss occurs on a relatively small scale resulting in very minor impairment, such as some loss in speed of thinking. In other cases damage can be extensive leading to significant impairments.
There will be a wide variation in exactly in how encephalitis affects the person in the long term. Tiredness, recurring headaches, difficulties with memory, concentration and balance are often reported as are mood swings, aggression and clumsiness. Epilepsy, as well as being a feature of the acute illness, may develop weeks or months after the illness has subsided. Physical problems may include weakness down one side of the body, loss of sensations and of control of bodily functions and movement. Speech and language problems are also common features. Speed of thought and reaction may be reduced.
Recovery is a long and slow process. An initial period of convalescence with plenty of rest is recommended. This should be followed by a programme of graded activity and rest over 3 – 6 months giving the brain the opportunity to restore function. In more severe cases a period in a brain injury rehabilitation unit may be necessary.
Compared to other infectious diseases, encephalitis has a high mortality rate. The illness can be very quickly fatal causing extreme trauma for all the family. It is difficult to understand why a virus infection in the modern world can have such devastating consequences.