INTRODUCTION: Reversible cerebral vasoconstriction syndrome (RCVS) is a cerebrovascular disorder associated with multifocal intracranial arterial constriction and dilation that occurs spontaneously or as a result of a stimulant. The authors present a case of RCVS in a patient who presented with a new-onset thunderclap headache a day after carotid endarterectomy (CEA). RCVS has been rarely reported after CEA.

CASE REPORT: A 65-year-old woman was evaluated for a new-onset thunderclap headache a day after left-sided CEA. Computed tomography (CT) of the head revealed left frontal and parietal subarachnoid hemorrhage (SAH). CT angiography did not show any saccular aneurysms or vessel stenosis. The initial impression was SAH related to reperfusion injury after carotid revascularization. Seven days postoperatively, the patient returned to the hospital with a persistent headache. CT revealed SAH in the vertex of the frontal region bilaterally. Magnetic resonance angiogram (MRA) of the head revealed multifocal stenosis of the intracranial circulation bilaterally. A follow-up MRA 9 weeks postoperatively showed interval improvement of the caliber of the circle of Willis branches and significant improvement of the multifocal stenosis. The patient was diagnosed with RCVS as a result of CEA.

CONCLUSION: The authors advise clinicians to consider RCVS as a cause of thunderclap headache or recurrence of a severe headache shortly after CEA-particularly with the presence of a nonaneurysmal convexity SAH.