Which condition is characterized by large amplitude sudden violent motions of the arms and legs on the same side?

The condition characterized by large amplitude sudden violent motions of the arms and legs on the same side is hemiballismus. This movement disorder typically results from a lesion in the contralateral subthalamic nucleus, often due to vascular accidents such as a stroke. The motor manifestations of hemiballismus are characterized by unpredictable, wild flinging or throwing movements of the limbs, primarily affecting one side of the body.

In contrast, dystonia involves sustained muscle contractions and abnormal postures, which do not typically result in the explosive, violent movements seen in hemiballismus. Chorea presents with irregular, non-repetitive movements that are more dance-like and can affect both sides of the body without the same amplitude and suddenness. Athetosis is associated with slow, writhing movements, often affecting the hands and feet, and typically does not exhibit the large amplitude motions characteristic of hemiballismus. Thus, hemiballismus is uniquely defined by its specific movement patterns and unilateral presentation.