Q: What is hemiballismus?

Answer: 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"  Hemiballismus means 'half ballistic', refers to the violent, flailing movements observed on one side of the body.

Clinical significance:  It could be one clinical signs of Stroke, Traumatic Brain Injury, ALS, Nonketotic Hyperglycemia, Tumor, Hypoglycemia due to pentamidine, cerebral toxoplasmosis etc.

http://youtu.be/t9jcccWzVPs