Hemiballismus Is A Very Rare Movement Disorder

Hemiballismus General Definition is a neurological sign that presents as a movement disorder , characterised by unilateral wild, large amplitude flinging movements of the arm and leg, normally causing falls and preventing postural maintenance.

History In experiments, several lesions were made in the basal ganglia structures in monkeys and then they monitored the results. They noticed that the majority of the time, the monkeys did not have any unusual movements. However, when at least twenty percent of the subthalamic nucleus was damaged, abnormal movements were seen in the limbs opposite to the side of the brain that was damaged. This observation caused scientists to believe that hemiballismus outside the subthalamic nucleus did not occur. It was not until much later that this classical model began to expand to include other areas of the basal ganglia and even some cortical structures. They also noticed that unlike human patients, the unusual movements in the monkeys were mainly in the lower extremeites. In about half of the monkeys, the hemiballismus continued until the monkey died. .

Other scientists have also worked on this perplexing disorder and have found that the symptoms can be induced by injecting kainic acid or ibotenic acid into the subthalamic nucleus. using these chemicals, they could destroy only four percent of the subthalamic nucleus and still see hemiballistic movements. However, the abnormal movements would usually disappear within four to five hours even though it did not appear as though the damaged tissue had healed. This suggests that the subthalamic nucleus is plastic enough to adapt to small amounts of damage in order to resume normal function.

Causes 1.

Stroke

Hemisballismus as a result of stroke occurs in only about 0.45 cases per hundred thousand stroke victims[1]., stroke is by far the most common cause of hemiballismus[5]. 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. 2. Traumatic Brain Injury

Hemiballismus can also occur as a result of traumatic brain injury. There are cases in which victims of assault of other forms of violence have

developed hemiballismus[2]. Through these acts of violence, the victim’s brain has been damaged and the hemiballistic movements have developed. 3. Amyotrophic Lateral Sclerosis

This disease causes neuronal loss and gliosis, which can include the subthalamic nucleus and other areas of the brain cause hemiballismus. 4. Nonketotic Hyperglycemia

Patients with nonketotic hyperglycemia can develop hemiballismus as a complication to the disease through the development of a subthalamic nucleus lesion[9]. This is the second most common reported cause of hemiballismus.

5.

Neoplasms

A neoplasm is an abnormal growth of cells. Cases have shown that if this occurs somewhere in the basal ganglia, hemiballismus can result[5].

6.

Vascular malformations

Vascular malformations can cause abnormal blood flow to areas of the brain. If too little blood is delivered to the basal ganglia, a stroke can occur[5].

Tuberculomas

7.

This is another form of tumor that can result in the brain as a result of a tuberculous meningitis infection. This type of tumor can also damage parts of the basal ganglia, sometimes resulting in hemiballismus[5].

Demyelinating plaques

8.

Demyelinating plaques attack the myelin sheaths on neurons. This decreases the conduction velocity of the neurons, making the signals received by the basal ganglia garbled and incomplete..

9. Complications from HIV infection Patients with HIV often have complications that arise along with AIDS. Hypoglycemia due to pentamidine use in patients with AIDS has been known to cause hemiballismus. In some patients, hemiballismus has been the only visible symptom to alert the physician that the patients may have AIDS.

Treatments •

Dopamine Blockers . Blocking

dopamine is effective in about ninety percent of patients.. •

Anticonvulsants An anticonvulsant called topiramate has helped

patients in three cases and may be a viable treatment for the future[10]. •

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[2]. •

Botulinum Injections New uses for botulinum toxin have included treatment of hemiballismus. However, this is still in the early stages of testing.. •

Tetrabenazine Tetrabenazine has been used to treat other movement disorders, but is now being used to treat hemiballismus. •

Antipsychotics

More research is being performed on the use of these types of drugs in treating hemiballismus[6]. •

Functional Neurosurgery[5] Surgery as a treatment should only be used on patients with severe hemiballismus that has not responded to treatment.

Prognosis

In the past, the prognosis for patients with this disease had been very poor; with many patients suffering from severe disability or death. Now, patients are responding remarkably well to current treatments and the majority of patients go into spontaneous remission. For those that do not go into remission, the symptoms of hemiballismus can generally be very well controlled with medication[5].