Hemiballismus

Neurological disorder characterized by involuntary movements

Hemiballismus is a rare movement disorder characterized by involuntary, violent, and wide-amplitude movements of the limbs on one side of the body. It is often associated with lesions in the subthalamic nucleus of the basal ganglia, which is a group of nuclei in the brain involved in the coordination of movement.

Signs and symptoms

File:Hemichorea and dystonia.ogv The primary symptom of hemiballismus is the presence of involuntary, flinging movements of the limbs. These movements are typically unilateral, affecting only one side of the body, and can be severe enough to interfere with daily activities. The movements are often described as violent and can involve the proximal parts of the limbs, such as the shoulders and hips.

Patients with hemiballismus may also experience hemichorea, which involves smaller, more rapid movements, and dystonia, which is characterized by sustained muscle contractions leading to abnormal postures.

Causes

Hemiballismus is most commonly caused by a lesion in the subthalamic nucleus, often due to a stroke. Other causes can include traumatic brain injury, tumors, infections, or metabolic disorders. In some cases, the exact cause of the lesion may not be identified.

Pathophysiology

The basal ganglia play a crucial role in the regulation of movement. The subthalamic nucleus is part of a circuit that modulates motor activity. Lesions in this area can disrupt the normal inhibitory control of the basal ganglia, leading to the excessive and uncontrolled movements seen in hemiballismus.

Diagnosis

Diagnosis of hemiballismus is primarily clinical, based on the characteristic movements and their unilateral nature. Neuroimaging techniques, such as MRI or CT scan, can be used to identify lesions in the subthalamic nucleus or other parts of the brain that may be responsible for the symptoms.

Treatment

File:Hemichorea and dystonia.ogv Treatment of hemiballismus focuses on managing symptoms and addressing the underlying cause. Medications such as antipsychotics (e.g., haloperidol) or anticonvulsants (e.g., valproic acid) can help reduce the severity of the movements. In some cases, surgical interventions, such as deep brain stimulation, may be considered.

Prognosis

The prognosis for hemiballismus varies depending on the underlying cause. In cases where the condition is due to a reversible cause, such as a metabolic disorder, symptoms may improve with appropriate treatment. However, if the condition is due to a permanent lesion, such as a stroke, the symptoms may persist, although they often decrease in severity over time.

Related pages

• Chorea
• Dystonia
• Basal ganglia
• Subthalamic nucleus