Hemiballismus is characterized by intermittent, large-scale movements on one side of the body. Which structure is most commonly involved?

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Multiple Choice

Hemiballismus is characterized by intermittent, large-scale movements on one side of the body. Which structure is most commonly involved?

Hemiballismus reflects disruption of the indirect pathway within the basal ganglia. A lesion of the subthalamic nucleus on one side reduces excitatory drive to the internal segment of the globus pallidus, leading to less inhibition of the thalamus and, consequently, excessive thalamocortical activity. This produces sudden, large, involuntary flinging movements on the opposite side of the body. The contralateral presentation comes from the crossing of motor and basal ganglia–thalamocortical circuits. The caudate and putamen are more commonly linked to chorea in other conditions, while cerebellar cortex damage causes ataxia rather than hemiballismus.

Hemiballismus reflects disruption of the indirect pathway within the basal ganglia. A lesion of the subthalamic nucleus on one side reduces excitatory drive to the internal segment of the globus pallidus, leading to less inhibition of the thalamus and, consequently, excessive thalamocortical activity. This produces sudden, large, involuntary flinging movements on the opposite side of the body. The contralateral presentation comes from the crossing of motor and basal ganglia–thalamocortical circuits. The caudate and putamen are more commonly linked to chorea in other conditions, while cerebellar cortex damage causes ataxia rather than hemiballismus.

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