What is Hemiballismus?
Hemiballismus, (previously known as ballism) is an extremely rare movement disorder which occurs as a result of decreased activity of the subthalamic nucleus in the basal ganglia, which causes ballistic, flailing and unwanted movements of the limbs. Certain metabolic abnormalities can also cause this condition, although this is rare. Hemiballismus means "half ballistic", which is referred to flailing violent movements occurring on one side of the body.
As mentioned above, Hemiballismus is extremely rare, so much so that it is 500 times rarer than Parkinson's disease. Hemiballismus can cause significant disability in a patient. Symptoms of Hemiballismus may decrease during sleep.
Ballism is a repetitive, always varying, involuntary movement of large amplitude of the proximal areas of the limbs. This is a constant activity and the movements are usually complex and combined. Patient has involuntary flinging motions of his/her extremities. These movements tend to be violent and the movements have wide amplitude to them. The movements of Hemiballismus are random and continuous and may involve the proximal and/or distal muscles on one side of the body. Facial muscles can also be involved in some cases. The arms and legs tend to move together. The movements will increase if the patient is active. If the patient relaxes, then the movements decrease. The severity of Hemiballismus can be measured by having the patient perform a sequence of basic, predetermined tasks where the hemiballistic movements are counted in a set time session. The patient is then rated on a severity scale, which will give the physician a method of comparing patients and assessing the range of this movement disorder.
Causes of Hemiballismus
Hemiballismus is a rare disorder and given below are some of the conditions, which can cause hemiballismus. However, it should be born in mind that if a patient suffers from one of the below disorders, it doesn't necessarily mean that he/she will also suffer from hemiballismus.
- Traumatic Brain Injury can cause Hemiballismus. Any type of injury which damages the patient's brain can result in development of the hemiballistic movements.
- Stroke can cause hemiballismus in around 0.45 cases in a hundred thousand stroke victims. However, stroke remains the most common cause of hemiballismus. Stroke causes death of the tissue due to lack of oxygen, which results in impaired blood supply. If there is death of the tissue, which helps to control movement then it sends damaged signals to the skeletal muscles, which can lead to hemiballismus.
- Non-ketotic Hyperglycemia can cause hemiballismus as a complication due to the development of a lesion in the subthalamic nucleus . Non-ketotic hyperglycemia is the second most common cause of hemiballismus. Elderly are primarily affected by it and individuals from East Asian origin are at a higher risk. This leads to a suggestion that there is some genetic disposition to hemiballismus due to hyperglycemia. When there is an increase in the blood glucose levels, then the Hemiballistic movements appear and as the blood glucose levels decrease back to normal, so do the movements. The time scale for this is often several hours. Patients suffering from this type of hemiballismus will have abnormalities in the putamen contralateral, globus pallidus and caudate nucleus which are revealed on imaging tests. According to the studies, hyperglycemia itself is not the main cause of hemiballistic movements, but the decreased production of GABA and acetylcholine and also the petechial hemorrhage occurring secondary to the hyperglycemia can be responsible for the hemiballistic movements.
- Amyotrophic Lateral Sclerosis causes loss of neurons and gliosis including the subthalamic nucleus and other regions of the brain. Any type of disorder which causes loss of neurons and gliosis has the tendency to cause hemiballismus.
- Neoplasm is a condition where there is abnormal cell growth. If there is formation of neoplasm in the basal ganglia, then it can cause hemiballismus.
- Vascular malformations lead to abnormal blood flow to regions of the brain. If there is decreased blood supply to the basal ganglia, then a stroke can occur which can lead to hemiballismus.
- Tuberculoma is a type of tumor, which occurs in the brain due to tuberculous meningitis infection. Tuberculoma can cause damage to some areas of the basal ganglia which can lead to hemiballismus.
- Demyelinating plaques damage the myelin sheaths of the neurons . This leads to reduction in the conduction velocity of the neurons, causing the signals, which are received by the basal ganglia to be incomplete and garbled. This disorganization in the signals results in the characteristic chaotic movements of the hemiballismus.
- HIV infection complications, such as hypoglycemia from pentamidine use, in patients who have AIDS also can cause hemiballismus. There are some cases where hemiballismus is the only apparent symptom of AIDS. This movement disorder can occur as result of a secondary infection, which develops from a compromised immune system. The most common infection which causes hemiballismus is cerebral toxoplasmosis. The lesions of this infection are most often found in the basal ganglia.
Treatment for Hemiballismus
In order to treat hemiballismus, it is important to treat the underlying cause of this disorder such as infections, hyperglycemia or neoplastic lesions. There are some patients who may not need treatment at all because the disorder is not that severe and may be self limited. Treatment comprises of:
- Dopamine Blockers are the most standard type of drug for treating hemiballismus. Anti-dopaminergic drugs, which block dopamine, are effective in around 90% of patients. Some of the dopamine blockers which are used are pimozide, perphenazine, haloperidol and and chlorpromazine.
- According to research, anticonvulsants, such as topiramate, have helped patients in around three cases and can be a potential treatment for hemiballismus.
- Botulinum Injections are relatively new in treating hemiballismus and are still in the early stages of testing. Botulinum injections do not deal with the neurological causes, but deal with the muscular manifestations of hemiballismus.
- Intrathecal baclofen (ITB) therapy has been in use for treating different types of movement disorders, such as multiple sclerosis and cerebral palsy. ITB therapy can also help in treating hemiballismus.
- Tetrabenazine is also used for treating other movement disorders and is now also being used for treating hemiballismus. Tetrabenazine has had considerable response in patients. However, reduction in the doses of tetrabenazine leads to recurrence of the symptoms. Tetrabenazine also works by reducing dopamine.
- Antipsychotics, such as olanzapine, have lead to significant recovery in a patient; however, haloperidol has not resulted in any improvement in patients. Research is still being carried out on antipsychotics in treating hemiballismus.
- Surgery such as Functional Neurosurgery is done only in severe cases of hemiballismus, which have not responded to other treatment. Deep Brain Stimulation of the globus pallidus and lesioning of the globus pallidus are the procedures, which can be used on human beings. Lesioning is more preferred over Deep Brain Stimulation, as the latter procedure requires more maintenance in the way of correct and effective stimulation of the brain.
Prognosis for Hemiballismus
Previously, the prognosis for patients with Hemiballismus has been quite poor where the patients have suffered from severe disability or death. But due to the advent of current treatment, there are many patients who are responding very well. However, there are also many patients who have gone into spontaneous remission; but for those patients who have not gone into remission; their symptoms have been generally well controlled with medications.