Diagnosis of unruptured asymptomatic cerebral aneurysms by magnetic resonance angiography.

The purpose of this study was to assess the incidence of unruptured asymptomatic cerebral aneurysms detected by magnetic resonance angiography (MRA). Three thousand patients without major neurological deficit had undergone MRA. MRA was obtained using three-dimensional time-of-flight method. Among the 3000 patients examined, 80 unruptured asymptomatic aneurysms were discovered in 68 patients (2.3%). Twenty-six were located on the internal carotid artery, 28 on the middle cerebral artery, 17 on the anterior communicating artery, 1 on the posterior cerebral artery and 8 on the vertebro-basilar artery. Thirty-seven patients underwent surgery. Mortality was zero and morbidity was 5%. Three patients who declined surgery died of subarachnoid haemorrhage in the ensuing 2.5 years.