Involuntary movements Hemiballismus 2010-07-09T12:21:41Z Hemiballismus is a very rare movement disorder. It is five hundred times rarer than Parkinson disease. Its effects can sometimes be severe enough to prevent patients from being able to perform daily functions. It is usually associated with structural brain lesions but can occur with metabolic abnormalities. The symptoms can also decrease while the patient is asleep, unlike some movement disorders. Ballism refers to very large-amplitude choreic movements of the proximal parts of the limbs, causing flinging and flailing limb movements. Ballism is most frequently unilateral, in which case it is referred to as hemiballism Ballismus HP:0100248 Hemiballismus is a rare movement disorder that is caused primarily by damage to various areas in the basal ganglia. Hemiballismus is usually characterized by involuntary flinging motions of the extremities. The movements are often violent and have wide amplitudes of motion. They are continuous and random and can involve proximal and/or distal muscles on one side of the body, while some cases even include the facial muscles. The more a patient is active, the more the movements increase. With relaxation comes a decrease in movements. UMLS:C0221169 SNOMEDCT_US:66637005