Dystonia A Neurological Disorder That Causes Involuntary Movement Of Muscles:Dystonia is a neurological disorder that causes involuntary movement of muscles, twisting and repetitive movements or abnormal postures.In most cases, dystonia, however, occur in adults and usually affects only one body part of your neck, face and hands, caused by other factors such as birth or other physical trauma, infection, poisoning or reaction to medications particularly neuroleptics.