Perimesencephalic Subarachnoid Hemorrhage in Pregnancy

Perimesencephalic subarachnoid hemorrhage (P-SAH) is a benign subset of subarachnoid hemorrhage. Only two cases of P-SAH during pregnancy have been reported in the literature. We describe a case of P-SAH detected at 29 weeks’ gestation, arose with severe bilateral frontal headache, neck rigidity, and vomiting. A diagnosis of P-SAH was confirmed on magnetic resonance angiography with no evidence of vascular malformation or bleeding sources and conservatively treated. Hemorrhage, vasospasm, and cerebellar edema observed on initial magnetic resonance angiography resolved after two months. The clinical course of P-SAH during pregnancy appears to be favorable. Our case shows for the first time in literature that magnetic resonance angiography is a valid diagnostic test for P-SAH during pregnancy that circumvents radiological risk associated with conventional imaging.