Detection of emboli after surgery for intracerebral aneurysms

BACKGROUND: Neurological change after surgery for cerebral aneurysm caused by embolic events is commonly suspected, but direct detection of emboli has not been possible in the past. Transcranial Doppler ultrasound (TCD) is able to detect emboli, and large numbers of emboli detected in TCD studies have been associated with radiological changes and clinical deterioration. METHODS: During a 2-year period, 11 patients were observed to have emboli during routine TCD studies after aneurysm surgery. The computed tomographic (CT) scans of these patients were reviewed for low-density areas, suggesting ischemia. All patients studied during a 1-year interval (July 1995-July 1996) served as a control group and were reviewed for similar CT findings, and the two groups were compared using Fisher's exact test. RESULTS: Nine of the 11 patients (82%) observed to have emboli developed low- density areas on their CT scans, whereas 30 of the 123 (24%) patients without emboli developed low-density areas on their CT scans. The difference was significant (P < 0.001, Fisher's exact test). Credible sources for emboli were readily identified in each of the 11 patients. CONCLUSION: TCD allows detection of emboli after aneurysm surgery, and this detection is strongly associated with CT evidence of ischemia. Although detection of emboli was relatively rare in this study, rates of emboli occurrence may increase if systematic monitoring is used.