Hemiballismus is a movement disorder that commonly affects the extremities and occasionally the face. It is characterized by involuntary movements of the affected body part, which are often described as violent and flailing.
When both the upper and lower extremities are affected by hemiballismus, it is common that the characteristic involuntary movements will occur simultaneously in the upper and lower extremities.
In some cases, hemiballismus may affect the muscles of facial expression. This would present as involuntary contraction of facial muscles localized to only one side, causing the patient to appear to be grimacing or having muscle twitches on that side.
One pathognomonic feature of hemiballismus is that the movements that characterize it are more pronounced with activity and less pronounced at rest. This is possibly related to the fact that hemiballismus typically results from dysfunction of the basal ganglia, which serve to regulate movement.
Hemiballismus is most likely a result of dysfunction of the basal ganglia. Recall that the basal ganglia refers to a group of subcortical nuclei which serve an important function in regulating and modulating movement, hence multiple movement disorders may be linked to dysfunction of some component of the basal ganglia. In the case of hemiballismus specifically, the contralateral subthalamic nucleus of the basal ganglia has been classically implicated, though recent studies have shown that dysfunction of other nuclei of the basal ganglia can cause hemiballismus as well.
The subthalamic nucleus is the most commonly and classically implicated part of the basal ganglia that is implicated in hemiballismus. The subthalamic nucleus is a component of the basal ganglia, a group of nuclei that control and modulate movement.
Stroke, both hemorrhagic and ischemic, is the most common underlying cause leading to damage and dysfunction of the brain nuclei most commonly implicated in hemiballismus.
Trauma leading to damage or ischemia of the basal ganglia may also cause hemiballismus.
Structural lesions such as neoplasms of the brain may cause dysfunction of the basal ganglia and/or subthalamic nucleus leading to hemiballismus.
Given the multiple etiologies leading to hemiballismus, specific treatment often depends on the underlying cause. However, dopamine blocking medications such as haloperidol and perphenazine have been shown to help reduce symptoms in patients with different underlying causes and is typically the medication class of choice when pharmacologic therapy is pursued. Other medications and classes occasionally used include baclofen, antipsychotics, and anticonvulsants.
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