Utility of Near-infrared Spectroscopy Monitoring in the Management of Hyperperfusion Syndrome after Intracranial Carotid Artery Stenting.

Cerebral hyperperfusion syndrome (HPS) is a rare complication of carotid endarterectomy (CEA) and stenting. There are only a few case reports about HPS after intracranial stenting, and its clinical course remains unclear. We report an unusual case of HPS after intracranial internal carotid artery (ICA) stenting. An 87-year-old woman underwent uneventful balloon angioplasty for the right intracranial ICA one year ago; then she presented with restenosis at the same arterial location. She then underwent an ICA stent placement procedure. Preoperative cerebral blood flow (CBF) studies revealed hemodynamic ischemia. At the time of surgery, the stenotic lesion was near-occlusion. Twelve hours after the successful stenting procedure, the patient became restless, and near-infrared spectroscopy (NIRS) indicated a blood flow increase to the affected side. Arterial spin labeling (ASL) imaging performed on the same day showed high signal intensity only in the right hemisphere. She was treated with sedation, blood pressure control, and minocycline hydrochloride administration. Because of the strict management under continuous monitoring with NIRS, her symptoms gradually improved over the next 6 days. The right-to-left difference observed with ASL imaging resolved 6 days after surgery, and she was discharged with no neurological deficit. This case highlights the utility of NIRS monitoring in the management of HPS after intracranial stenting.