CLINICAL PRESENTATION: A 48-year-old woman presented with sudden severe headache. Localized right convexity SAH was observed on computed tomography (CT) scan, but the origin could not be detected despite extensive workup covering the entire head using 3.0-Tesla magnetic resonance (MR) imaging with MR angiography and CT angiography combined with venous-phase imaging using a 320-detector row CT scanner. Subsequent digital subtraction angiography (DSA) performed 2.5 hours after admission failed to reveal any cause of SAH; however, a right fronto-parietal avascular region was suspected to be due to a newly developed intracerebral hematoma. The lesion was simultaneously confirmed by angiographic cone-beam CT imaging. Because she remained neurologically intact, we decided to perform follow-up study later with medical management. However, she developed left hemiparesis 3 hours after DSA. CT scan demonstrated progression of the hematoma and her symptoms gradually worsened. Emergent surgical exploration along the SAH superficial to the postcentral sulcus and hematoma evacuation were performed, with favorable functional outcome. Pathologic examination confirmed cryptic vascular malformation with several abnormally dilated arterioles within the subarachnoid space surrounded by thick SAH clot.
CONCLUSION: It is important to consider the possibility of ruptured cryptic vascular malformation as a cause of nontraumatic nonaneurysmal convexity SAH when recurrent hemorrhage occurs despite thorough diagnostic workup, since surgical resection may be the only curative treatment option to eliminate the risk of rebleeding and disabling symptoms.
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