Hemiballismus

Hemiballismus, formerly called ballism, is a very rare movement disorder, caused in most cases by a decrease in activity of the subthalamic nucleus of the basal ganglia, resulting in the appearance of flailing, ballistic, undesired movements of the limbs. It can also appear rarely due to certain metabolic abnormalities. It is a rare movement disorder, being 500 times more rare than Parkinson's disease. Hemiballismus can cause significant disability. Symptoms can decrease during sleep.

General Definition

Ballism was defined as "Repetitive, but constantly varying, large amplitude involuntary movements of the proximal parts of the limbs. This activity is almost ceaseless and movements are often complex and combined" by Meyers in 1968. 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. Some cases even include the facial muscles. It is common for arms and legs to move together. The more a patient is active, the more the movements increase. With relaxation comes a decrease in movements. Physicians can measure the severity of the disorder by having the patient perform a series of basic, predetermined tasks and counting the hemiballistic movements during a set time session. The physicians then rate the patient on a severity scale. This scale gives scientists and clinicians a way to compare patients and determine the range of the disorder.