Hemiballismus or hemiballism is a basal ganglia syndrome resulting from damage to the subthalamic nucleus in the basal ganglia. that is characterized by pronounced involuntary limb movements on one side of the body and can cause significant disability. Rarely it affects both sides of the body.
Hemiballismus differs from chorea in that the movements occur in the proximal limbs whereas in chorea the limb movements are in the distal limbs.
Symptoms
Ballism was defined by Meyers in 1968 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 is usually characterized by involuntary flinging motions of the extremities. They are continuous and random and can involve proximal or distal muscles on one side of the body. Some cases even include the facial muscles. 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.
The name hemiballismus literally means "half ballistic", referring to the violent, flailing movements observed on one side of the body.
Causes
In examining the causes of hemiballismus, it is important to remember that this disorder is extremely rare. While hemiballismus can result from the following list, just because a patient has one of these disorders does not mean they will also experience hemiballismus.
Stroke
Hemisballismus as a result of stroke occurs in only about 0.45 cases per hundred thousand stroke patients. A stroke causes tissue to die due to a lack of oxygen resulting from an impaired blood supply. In the basal ganglia, this can result in the death of tissue that helps to control movement. As a result, the brain is left with damaged tissue that sends damaged signals to the skeletal muscles in the body. The result is occasionally a patient with hemiballismus.
Traumatic brain injury
Hemiballismus can also occur as a result of a traumatic brain injury. There are cases in which survivors of assault or other forms of violence have developed hemiballismus. This is the second most common reported cause of hemiballismus. It can be found primarily in the elderly and many of the reported cases have come from East Asian origin, which suggests that there may be some genetic disposition to development of hemiballismus as a result of hyperglycemia. Hemiballistic movements appear when blood glucose levels get too high and then subside once glucose levels return to normal. This time scale for this is usually several hours. In patients with this type of hemiballismus, imaging reveals abnormalities in the putamen contralateral to the movements as well as the globus pallidus and caudate nucleus. While the hyperglycemia itself is not the cause of the hemiballistic movements, it has been suggested that petechial hemorrhage or a decreased production of GABA and acetylcholine could result secondary to the hyperglycemia. One of these issues could be responsible for the hemiballistic movements. Injury to this area or its efferent or afferent connections can induce this disorder contralateral to the side of the lesion. It was traditionally thought that the disorder was only caused by injury to the subthalamic nucleus, but later studies have shown that damage to other basal ganglia regions can also be responsible for causing this disorder. Increases in activity in this area causes there to be an inhibition of the motor thalamus. This causes cortical activation and thus a movement inhibition. In the case of hemiballismus, the opposite occurs, leading to the characteristic large, irregular movements.
ITB therapy
Intrathecal baclofen (ITB) therapy is used to treat a variety of movement disorders such as cerebral palsy and multiple sclerosis. It can also be a possibility to help treat hemiballismus.