Dystonia

Dystonia is a neurological disorder in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. It may be inherited or caused by birth-related trauma, physical trauma, infection, or a number of other possibilities.

This disorder may range from mild (facial twitches or limb twitches) to severe (whole body). It can also be attributed to one's vocals, where the person won't be able to talk and will use a machine to communicate.

There is currently no treatment for patients suffering from dystonia.

This one is a pretty severe case.