Subintimal hemorrhage in an unruptured superior cerebellar artery aneurysm: Prelude to rupture: Case report

Objective and Importance: An intracranial aneurysm that hemorrhages into the subintimal layer of the blood vessel is a rare clinical entity. Such a hemorrhage is distinct from dissecting aneurysms or pseudoaneurysms of the cerebral circulation and may represent an aneurysm in the process of rupturing. The authors report their experience in the management of a patient who presented with a subintimal hemorrhage of a superior cerebellar aneurysm. Clinical Presentation: A 54-year-old man presented with a progressively worsening headache over the course of 3 days. A noncontrast computed tomographic scan did not demonstrate subarachnoid hemorrhage but was suggestive of a posterior circulation aneurysm. Intervention: In the absence of subarachnoid hemorrhage on the computed tomographic scan, negative findings for xanthochromia in the cerebrospinal fluid, and no evidence of subarachnoid blood on magnetic resonance imaging, a conventional four-vessel cerebral angiogram was performed, which revealed a right superior cerebellar artery aneurysm. Further evaluation on magnetic resonance imaging demonstrated abnormal signal conforming to the aneurysm wall, suggesting the presence of a contained subintimal hemorrhage. The patient underwent a right frontotemporal craniotomy (half-and-half approach) for clip ligation of the superior cerebellar artery aneurysm. Conclusion: Subintimal hemorrhage of an aneurysm in the absence of subarachnoid hemorrhage may be conceptually considered an aneurysm in the process of rupturing. Thus, aneurysms found in the acute setting may benefit from further workup, such as magnetic resonance imaging or highly selective angiographic evaluation of the aneurysm itself. Timely surgical intervention may prevent otherwise imminent rupture into the subarachnoid space.