A 60-year-old man with a history of atrial fibrillation had an acute onset of ballistic movements of the left limbs with sensory extinction (video on the Neurology® Web site at www.neurology.org). The patient was treated with risperidone and anticoagulant; symptoms subsided 3 days later. Brain MRI showed acute infarction of the right posterior parietal lobe (figure 1) and SPECT revealed hypoperfusion in the right frontoparietal areas (figure 2).
Axial view of diffusion-weighted MRI at frontoparietal level.
(A) Axial view of SPECT at frontoparietal level. (B) 3D cortical perfusion SPECT image at the same level. The arrows indicate hypoperfusion of right frontoparietal regions.
Hemiballism is a rare movement disorder often associated with lesions in the subthalamic nucleus (STN). Lesions outside the STN are rarely reported.1,2 A disorganized sensorimotor integration in frontoparietal lobes resulting in decreased excitatory output to STN probably causes this phenomenon.
STUDY FUNDING
No targeted funding reported.
DISCLOSURE
The authors report no disclosures relevant to the manuscript. Go to Neurology.org for full disclosures.
Mystery Case Responses
The Mystery Case series was initiated by the Neurology® Resident & Fellow Section to develop the clinical reasoning skills of trainees. Residency programs, medical student preceptors, and individuals were invited to use this Mystery Case as an education tool. Responses were solicited through a group e-mail sent to the American Academy of Neurology Consortium of Neurology Residents and Fellows and through social media. All the answers that we received came from individual residents rather than groups and they were all well-reasoned and thoughtful. Most respondents (over 90%) correctly identified the involuntary, large-amplitude, flinging movements of the left side limbs as hemiballismus and considered an ischemic stroke as the most likely mechanism; 30% of respondents considered lesion sites other than the STN, including basal ganglia and cortex.
The teaching point of this Mystery Case is that while most injuries causing hemiballismus occur within the subcortical nuclei (classically the STN), there are reported cases of damage to cortical structures causing hemiballismus. In addition, lesions of the STN usually produce a more severe movement disorder than lesions of other structures.1
Dragos A. Nita, MD, PhD
The Hospital for Sick Children, University of Toronto, Toronto, Canada.
Footnotes
Supplemental data at www.neurology.org
- © 2013 American Academy of Neurology
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