Hemichorea-hemiballismus caused by postoperative hyperperfusion after clipping of a giant unruptured middle cerebral artery aneurysm

BACKGROUND: Movement disorders after the clipping for an unruptured giant aneurysm are rare. The information on the pathogenesis and treatment options for this condition is largely unknown. CASE DESCRIPTION: An 82-year-old female with no neurological deficits underwent a clipping for a giant middle cerebral artery (MCA) aneurysm. Immediately after surgery, she presented with hemichorea–hemiballismus (HC–HB) on the left side. Postoperative angiograms and single-photon emission computed tomography demonstrated the hyperperfusion in the right frontal cortex and the decreased perfusion in the basal ganglia, indicating that the abrupt hemodynamic changes due to the obliteration of the giant aneurysm caused the dysfunction of the frontal cortical and subcortical pathway and the basal ganglia. Administration of tiapride hydrochloride was dramatically effective in controlling the HC–HB until the hyperperfusion resolved. Single-photon emission computed tomography obtained 8 weeks after surgery revealed that the cerebral blood flow had been normalized in the right frontal cortex. The relative hypoperfusion of the right basal ganglia was also resolved. Then tiapride hydrochloride was discontinued without a relapse of HC–HB. CONCLUSION: This case appears consistent with the theory that the connecting fibers responsible for the development of HC–HB are also located in the frontal lobe. The treatment of giant aneurysms involving the M1 portion can cause abrupt hemodynamic changes in both frontal cortex and the basal ganglia, which can potentially induce postoperative movement disorders.