RCH most commonly follows supratentorial neurosurgical procedures, performed with the patient in the supine position, that involve opening of cerebrospinal fluid cisterns or the ventricular system (such as unruptured aneurysm repair or temporal lobectomy). Preoperative aspirin use and moderately elevated intraoperative systolic blood pressure are potentially modifiable risk factors associated with the development of RCH. Although RCH can cause death or major morbidity, most cases are asymptomatic or exhibit a benign course. Cerebellar "sag" as a result of cerebrospinal fluid hypovolemia, causing transient occlusion of superior bridging veins within the posterior fossa and consequent hemorrhagic venous infarction, is the most likely pathophysiological cause of RCH.

Cerebellar hemorrhage must be considered in patients with unexplained neurological deterioration after spinal surgery. Dural opening with loss of cerebrospinal fluid has occurred in every reported case of cerebellar hemorrhage complicating a spinal procedure, supporting the hypothesis that loss of cerebrospinal fluid is central to the pathogenesis of this condition. Because remote cerebellar hemorrhage can occur after procedures with the patient in the supine, sitting, and prone positions, patient positioning seems unlikely to play a causative role in its occurrence.

Isolated aneurysms of the spinal artery (not associated with arteriovenous malformations) are exceptionally rare. Fewer than 17 cases have been reported in the literature. We report a case of an isolated spinal artery aneurysm causing acute subarachnoid hemorrhage. Spinal artery aneurysms are contrasted with the more common intracranial aneurysms in terms of presentation and pathogenesis. The various clinical presentations of spinal artery aneurysms are discussed as well. A summary of all reported cases of spinal aneurysms, with and without associated arteriovenous malformations, is listed.

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