Atraumatic convexal subarachnoid hemorrhage: clinical presentation, imaging patterns, and etiologies

Abstract

Objective: To identify patterns of clinical presentation, imaging findings, and etiologies in a cohort of hospitalized patients with localized nontraumatic convexal subarachnoid hemorrhage.

Methods: Twenty-nine consecutive patients with atraumatic convexal subarachnoid hemorrhage were identified using International Classification of Diseases-9 code from 460 patients with subarachnoid hemorrhage evaluated at our institution over a course of 5 years. Retrospective review of patient medical records, neuroimaging studies, and follow-up data was performed.

Results: There were 16 women and 13 men between the ages of 29 and 87 years. Two common patterns of presentations were observed. The most frequent presenting symptom in patients < or =60 years (n = 16) was a severe headache (n = 12; 75%) of abrupt onset (n = 9; 56%) with arterial narrowing on conventional angiograms in 4 patients; 10 (p = 0.003) were presumptively diagnosed with a primary vasoconstriction syndrome. Patients >60 years (n = 13) usually had temporary sensory or motor symptoms (n = 7; 54%); brain MRI scans in these patients showed evidence of leukoaraiosis and/or hemispheric microbleeds and superficial siderosis (n = 9; 69%), compatible with amyloid angiopathy (n = 10; p < 0.0001). In a small group of patients, the presentation was more varied and included lethargy, fever, and confusion. Four patients older than 60 years had recurrent intracerebral hemorrhages in the follow-up period with 2 fatalities.

Conclusion: Convexal subarachnoid hemorrhage is an important subtype of nonaneurysmal subarachnoid bleeding with diverse etiologies, though a reversible vasoconstriction syndrome appears to be a common cause in patients 60 years or younger whereas amyloid angiopathy is frequent in patients over 60. These observations require confirmation in future studies.

Figure 1 Superficial subarachnoid hemorrhage (SAH) in a patient with amyloid angiopathy (A) Admission CT scan of a 70-year-old man with repeated episodes of right-sided numbness and speech difficulty demonstrates a left frontal SAH (arrow). (B) Brain MRI shows evidence of superficial siderosis (arrow) and cortical microbleeds (arrows) involving the frontal lobes.

Figure 2 Convexal subarachnoid hemorrhage (SAH) in a patient with cerebral vasoconstriction syndrome (A) CT scan of a 56-year-old man with severe headaches showing presence of superficial convexal SAH along bilateral posterior frontal lobes (arrows). (B) Conventional angiogram performed a day later shows multiple vessel narrowings (arrows) involving the branches of the posterior and anterior cerebral arteries. A repeat angiogram performed 4 weeks later showed restitution of normal arterial caliber (not shown).