gms | German Medical Science

Objective: The outcome after aneurysm surgery may be compromised by cerebral ischemia caused by clip stenotization of adjacent vessels. In AVM surgery, proof of blood flow reduction in the draining veins during step-wise occlusion of large feeders could be helpful. The intraoperative microvascular Doppler sonography (IMDS) is a good established monitoring tool in vascular surgery for vessel blood flow velocity (BFV) monitoring. However, identification of subtotal vessel compromise during aneurysm surgery and of stepwise BFV reduction during AVM resection by IMDS is difficult, because the measured BFV may substantially vary due to changing insonation angles and insonated vessel segments. To overcome these limitations we used a neuronavigated IMDS (NIMDS) in a subsequent series of aneurysm and AVM surgery.

Method: We used the NIMDS, based on CT-angiography in 28 patients. Most of the patients had innocent or incidental aneurysm (n=20), 5 patients with aneurysmal subarachnoid hemorrhage. 3 patients underwent AVM resection. Autosegmentation was applied to create a 3D reconstruction of the basal arteries and the aneurysm or the nidus and the arterialized veins. The trajectory as well as the mean VBF values were simultaneously registered prior and after aneurysm clipping and repeatedly during major feeder occlusion in AVM cases using the same trajectory. Deviation of mean VBF values pre-and post clipping were calculated.

Results: We performed 58 measurements of mean VBF changes in aneurysm surgery. Mean deviation between the pre- and post clipping VBF values were 2,37 cm/s ((-25)-29) for the first and 0,32cm/s ((-23)-19) for the second value. There was a statistically significant correlation between the two mean VBF values before and after clipping, (r=0.72; p<0.0001 vs. r=0.55; p<0.0001). Only one patient experienced new neurological deficit postoperatively due to occlusion of a not monitored perforating vessel. In the 3 AVMs, stepwise mean VBF reduction with each major feeder occlusion starting with 34/30 cm/s was seen.

Conclusions: NIMDS is a reliable and save monitoring technique of even minimal changes in VBF during vascular surgery. These results suggest that vessel compromises, which have the potential of leading to infarction, would easily be detectable during aneurysm surgery. During AVM surgery, VBF monitoring might guide privileged occlusion of larger feeders first.