Should Patients Be Counseled About Possible Recurrence of Perimesencephalic Subarachnoid Hemorrhage?

Background: Isolated perimesencephalic subarachnoid hemorrhage (pSAH) is a distinct subtype of subarachnoid hemorrhage (SAH) seen in 5% of patients with SAH, with a relatively benign natural course and good outcome compared with diffuse, aneurysmal SAH. Traditionally, the prognosis of pSAH is believed to be excellent compared with aneurysmal SAH, with no risk of recurrent hemorrhage after long-term follow-up. We describe a case of pSAH in which the patient had a recurrent perimesencephalic bleed 8 years after the initial episode. There are 5 previous reports of recurrent pSAH in existing literature.

Case report: A patient in sixth decade of life with no history of trauma presented in 2006 with acute-onset, severe headache, and "off-balance" gait. The patient was diagnosed with pSAH on the basis of computed tomography angiography and digital subtraction angiography. The patient was discharged, and follow-up computed tomography angiography over the next 2 years revealed no underlying vascular anomaly. The patient presented in 2014 with sudden onset of headache, similar to the previous episode with no new neurologic signs. Patient had repeated imaging over the succeeding 2 years, which were all negative for new blood or source of subarachnoid bleed.

Review and discussion: There are only a couple of case reports of recurrent pSAH, some of which were defined questionably. We review the reported cases and discuss the imaging results and outcome. Considering the rarity, low risks of complications, as well as the good outcome even after recurrence, we do not recommend routinely counseling patients about possibility of recurrence of pSAH.