A 61-year-old man with a medical history significant for hyperlipidemia, hypothyroidism, and tonsillar cancer in remission presented with acute-onset left arm weakness. He presented 30 minutes after onset of symptoms and his National Institutes of Health Stroke Scale score was 5 on arrival for left facial droop, right gaze preference, and left homonymous hemianopia. There was a mild left proximal arm weakness but no pronator drift. Computed tomography (CT) of the head did not show any hemorrhage and his Alberta Stroke Program Early CT Score was 9. CT angiogram showed a distal right M2 thrombus. The patient received tissue plasminogen activator, but he was deemed not to be a candidate for mechanical thrombectomy given the distal clot location. Symptoms resolved within 24 hours. Magnetic resonance imaging of the brain revealed an acute infarct of the right insula and temporal cortex with no subcortical involvement (Figure). He started treatment with aspirin and clopidogrel, along with a high-intensity statin. Two days after presentation, the patient developed involuntary, large-amplitude, irregular, flinging movements of the left extremities that were insuppressible (Video). A second CT of the head exhibited known hypodensity in the right superior temporal lobe and insular cortex, without any significant change from prior magnetic resonance imaging. Routine electroencephalography did not show epileptiform activity, though no abnormal movements were observed during this study and the patient had preserved awareness during these events. No electrolyte abnormalities were seen. Left hemiballismus resolved spontaneously within 2 days without any pharmacological intervention. He continued to have left homonymous hemianopia on discharge.