Non-aneurysmal perimesencephalic subarachnoid hemorrhage in a middle-aged female possibly triggered by Valsalva-like event and uncontrolled hypertension: a case report.

Introduction: Non-aneurysmal perimesencephalic subarachnoid hemorrhage (NAPMSAH) is a rare subtype of subarachnoid hemorrhage with a generally benign course and accounts for a small proportion of spontaneous SAH cases. Compared with other SAH populations, patients with this condition are more commonly male and less likely to have a history of smoking or hypertension. Case presentation: We report a 58-year-old hypertensive woman who presented with sudden, severe headache and repeated vomiting without focal neurological deficits. She also had a history of intermittent vomiting associated with gastroesophageal reflux disease. Brain CT showed perimesencephalic subarachnoid hemorrhage, and CT angiography was negative for aneurysm or vascular malformation, confirming NAPMSAH. She was managed conservatively, with full clinical recovery. Discussion: NAPMSAH is believed to result from venous congestion due to impaired deep cerebral venous drainage, possibly triggered by hypertension and Valsalva-like maneuvers like vomiting. Although the prognosis is excellent, aneurysmal SAH must be excluded, and imaging remains crucial for diagnosis and risk stratification. Conclusion: NAPMSAH is a rare but important cause of acute headache, with generally good outcomes. Early recognition and imaging are essential to exclude aneurysmal hemorrhage and ensure appropriate management.