[A case with diffuse vasospasm after perimesencephalic nonaneurysmal subarachnoid hemorrhage].

Perimesencephalic nonaneurysmal subarachnoid hemorrhage(PNSH), defined as bleeding in the cisterns around the midbrain with a negative four-vessel angiographic study, is uniformly associated with an excellent outcome without associated rebleeding or symptomatic vasospasm. Angiographic vasospasm is uncommon in patients with this disease, and if vasospasm is present, severe and diffuse angiographical vasospasm is rare. We report a case with PNSH who developed severe and diffuse angiographic vasospasm. The patient was a 52-year-old woman who suffered an acute severe headache. We diagnosed PNSH from CT and angiographical findings, and treated her conservatively. Serial angiography, that was performed on the fourteenth day after hemorrhage, showed diffuse and severe angiographic vasospasm affecting both the anterior and the posterior circulation. She was treated with normovolemia, and remained no neurological symptom. Follow-up MR angiography showed improvement of the angiographic vasospasm. When the presence of diffuse and severe vasospasm is detected, a diagnosis of PNSH should not be excluded.