To report a rare manifestation of moyamoya angiopathy presented with sex-induced headache and propose possible explanations.

Patients with moyamoya angiopathy may present with a variety of symptoms. Cerebral ischemia or hemorrhage with focal neurological deficits are the most important clinical presentations. Headache, usually with migraine-like features, is a frequent presenting symptom in patients with moyamoya angiopathy, which resulted from dilated meningeal or leptomeningeal collateral vessels. On the other hand, sex-induced headache could be primary or secondary. To date, sex-induced headaches in the setting of moyamoya angiopathy has not been reported previously. 

Case Report and review of the literature. 

A 51-year-old female in Taiwan without preexisting diseases presented with thunderclap headache during sex activities, followed by a persisting moderate dull headache for two weeks. During this period, another thunderclap headache was triggered by sexual activity. An initial neurological examination was not remarkable. The brain magnetic resonance imaging (MRI) showed almost complete occlusion of left paraclinoid internal carotid artery with moyamoya-like vessels from lenticulostriate arteries. Serial workup confirmed she has antiphospholipid syndrome with moyamoya angiopathy. Her headache subsided with oral nimodipine 120mg/day with 4 divided doses for 3 months. Also, she received anticoagulant for stroke prevention. 

Based on literature review, sex-induced headache has never been reported in patients with moyamoya angiopathy. According to our findings, the mechanism underlying sex-induced thunderclap headache may attribute to vasospasm, similar with reversible cerebral vasoconstriction syndrome. For the high probability of headache related to vascular disease, patients with sex-induced headache warrant a head MR angiography scan.