This report describes a rare case of a distal anterior choroidal artery aneurysm which developed intraventricular haemorrhage without subarachnoid haemorrhage as shown on computerized tomographic (CT) scan. A 69-year-old hypertensive man suddenly became unconscious. An emergency CT scan showed a severe intraventricular haemorrhage and a small round low-dense lesion within the haematoma at the right trigone. The haematoma with obstructive hydrocephalus made the lateral ventricles larger on the right than on the left. CT scan could not detect any subarachnoid haemorrhage. Right interal carotid angiography revealed a saccular aneurysm at the plexal point of the right anterior choroidal artery. We approached the aneurysm and the small round lesion through the trigone via a right temporo-occipital corticotomy. We could clip the aneurysmal neck and remove the intraventricular haematoma and the papillary cystic mass (corresponding to the small round lesion on CT scan) totally in one sitting. Histological examination revealed the aneurysm to be a true one and the papillary cystic mass to be a choroid plexus cyst.

A 38-year-old male presented with vertebral artery dissecting aneurysm manifesting as subarachnoid hemorrhage. An attempt at trapping the aneurysm failed, so the vertebral artery could only be clipped proximally. Rebleeding occurred, resulting in death, probably due to excessive length of the dissection requiring thrombosis and/or retrograde dissection due to back pressure from the contralateral vertebral artery.

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Diffusion-weighted and perfusion-weighted magnetic resonance (MR) imaging were investigated as a method to detect diffusion-perfusion mismatch in the early stages of vasospasm in 17 patients with acute subarachnoid hemorrhage after aneurysm clipping. Single photon emission computed tomography (SPECT) with N-isopropyl-p-[ 123 I]iodoamphetamine was also performed. Diffusion-perfusion mismatch was clearly identified in the 3 patients who manifested clinical deterioration. Perfusion-weighted imaging showed increased mean transit time, normal cerebral blood flow, and increased or normal cerebral blood volume. SPECT revealed no earlier signs of vasospasm. Diffusion-perfusion mismatch was clearly demonstrated in the early stages of vasospasm, so may be useful for early identification of ischemia in vasospasm and initiating appropriate treatment.

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