Spontaneous isolated convexity subarachnoid hemorrhage: presentation, radiological findings, differential diagnosis, and clinical course

Clinical article

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The clinical characteristics and overall outcome in patients with spontaneous isolated convexity subarachnoid hemorrhage (SAH) are not well described in the literature. The purpose of this study was to examine the mode of presentation, common origins, radiographic findings, and clinical course in a large case series of such patients.


A retrospective single-center chart review of all patients in whom nontraumatic primary convexity SAH was diagnosed between 2002 and 2007 was performed. Twenty patients were identified and analyzed for presenting symptoms, radiological and laboratory findings, hospital course, and outcome.


There were 15 women and 5 men in our series, and the mean age was 52 years (range 18–86 years). The most common presenting symptom was headache, with 15 patients experiencing it as a chief complaint. Other frequent manifestations included altered mental status (8 patients), focal neurological deficits (7), and seizure (4 patients). An underlying cause of the hemorrhage was identified in 13 cases, whereas the remainder went unresolved. Of the known causes, 5 were due to posterior reversible encephalopathy syndrome, 3 were caused by thrombocytopenia or anticoagulation, and the remainder were isolated cases of lupus vasculitis, drug-induced vasculopathy, postpartum cerebral angiopathy, hypertensive microangiopathy, and Call–Fleming syndrome. All patients with unknown disease origins had favorable outcomes, whereas 8 of 13 patients with an identifiable underlying disorder experienced favorable outcomes.


Spontaneous isolated convexity SAH is rarely caused by aneurysm rupture, has a distinct mode of presentation, and generally carries a more favorable prognosis than that of aneurysmal SAH.

Abbreviations used in this paper: AVF = arteriovenous fistula; AVM = arteriovenous malformation; CSF = cerebrospinal fluid; DS = digital subtraction; PRES = posterior reversible encephalopathy syndrome; SAH = subarachnoid hemorrhage; SCA = superior cerebellar artery.

Article Information

Address correspondence to: Daniel Refai, M.D., Department of Neurosurgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8057, Saint Louis, Missouri 63110. email: refaid@nsurg.wustl.edu.

© AANS, except where prohibited by US copyright law.



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    Case 18. Neuroimages demonstrating convexity SAH associated with PRES. On a head CT scan obtained without contrast material (A), hyperdensity is seen along the right frontal sulci, consistent with SAH (white arrow). There is also a vague focus of hypodensity within the left parietal lobe (black arrow). Further evaluation by FLAIR MR imaging revealed hyperintensity over the right frontal lobe corresponding to the known SAH. Additional FLAIR images revealed hyperintensity predominantly involving the white matter of the left more than the right parietal lobe (B), with no corresponding diffusion restriction to suggest ischemia (C). These changes represent vasogenic edema due to PRES.

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    Case 13. Angiograms demonstrating convexity SAH associated with Call–Fleming syndrome. A: Right vertebral angiogram, anteroposterior injection. Subtle mild irregularity of both SCAs is present, a change from the initial study obtained on admission. B: A third angiogram obtained 10 days later, following clinical deterioration and an MR imaging study showing multiple small acute infarcts in the right parietooccipital convexity with an associated left occipital hematoma (MR image not shown). The cerebral angiogram depicted multiple new severe arterial narrowings, which were worst in the posterior circulation, but also involved both intracranial carotid artery territories.



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