Perimesencephalic Nonaneurysmal Subarachnoid Hemorrhage After Clipping of an Unruptured Aneurysm

BACKGROUND: Perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSAH) is a benign form of subarachnoid hemorrhage with an excellent clinical outcome. The cause of PNSAH remains unknown. We report a case of PNSAH in a patient with a history of clipping of an unruptured aneurysm. PNSAH after clipping of an unruptured aneurysm is extremely rare. CASE DESCRIPTION: A 56-year-old man with a history of clipping surgery for an unruptured aneurysm 10 months previously presented with severe headache. No precipitating causes were shown; however, the patient had been engaged in an exertional activity before the event. After conservative treatment, he was discharged home without any complication from the hemorrhage. CONCLUSIONS: On the basis of this case report, clinicians should consider the possibility of PNSAH in a patient who had an unruptured aneurysm previously treated with clipping. Nevertheless, diagnostic workup can be more important than keeping in mind that a subarachnoid hemorrhage might be a PNSAH.