Incidence and possible causes of nontraumatic convexal subarachnoid haemorrhage in Chinese patients: A retrospective review

Objective: To explore the incidence and possible underlying pathogenic mechanisms of nontraumatic convexal subarachnoid haemorrhage (cSAH; a rarely reported condition) in a cohort of Chinese patients. Methods: Medical records from all patients with subarachnoid haemorrhage (SAH) who had been treated at Peking University Third Hospital, China, between January 2010 and December 2014 were retrospectively reviewed to identify cases of cSAH. Results: Of 144 patients with SAH, cSAH was observed in 14 cases (9.7%). The most frequent presenting symptoms in cSAH cases were severe headache (n = 8) and a focal neurological deficit (n = 8). The parietal (10/14 patients, 71.4%) and frontal (9/14 patients, 64.3%) lobes were the most common haemorrhage sites. Cause of cSAH was identified in 11 patients: in seven cases (50.0%), significant stenosis or occlusion in the internal carotid artery system, ipsilateral to cSAH, was reported; in four cases, cSAH was caused by cerebral venous sinus thrombosis, cerebrovascular malformation, anticoagulant therapy or possible cerebral amyloid angiopathy. Conclusion: cSAH is an important subtype of nonaneurysmal SAH, with diverse aetiologies. In the present study, internal carotid artery system atherosclerotic stenosis was the most frequent cause of cSAH.