Intraoperative microvascular Doppler monitoring in intracranial aneurysm surgery

Background Surgical treatment of intracranial aneurysms is often compromised by incomplete exclusion of the aneurysm or stenosis of parent vessels. Intraoperative microvascular Doppler (IMD) is an attractive, noninvasive, and inexpensive tool. The present study aimed to evaluate the usefulness and reliability of IMD for guiding clip placement in aneurysm surgery. Methods A total of 92 patients with 101 intracranial aneurysms were included in the study. IMD with a 1.5-mm diameter, 20-MHz microprobe was used before and after clip application to confirm aneurysm obliteration and patency of parent vessels and branching arteries. IMD findings were verified postoperatively with digital subtraction angiography (DSA) or dual energy computed tomography angiography (DE-CTA). Ninety consecutive patients, harboring 108 aneurysms, who underwent surgery without IMD was considered as the control group. Results The microprobe detected all vessels of the Circle of Willis and their major branches. Clips were repositioned in 24 (23.8%) aneurysms on the basis of the IMD findings consistent with incomplete exclusion and/or stenosis. IMD identified persistent weak blood flow through the aneurismal sac of 11 of the 101 (10.9%) aneurysms requiring clip adjustment. Stenosis or occlusion of the parent or branching arteries as indicated by IMD necessitated immediate clip adjustment in 19 aneurysms (18.8%). The mean duration of the IMD procedure was 4.8 minutes. The frequency of clip adjustment (mean: 1.8 times per case) was associated with the size and location of the aneurysm. There were no complications related to the use of IMD, and postoperative angiograms confirmed complete aneurysm exclusion and parent vessel patency. About 8.3% (9/108) aneurysms were unexpectedly incompletely occluded, and 10.2% (11/108) aneurysms and parent vessel stenosis without IMD were detected by postoperative DSA or DE-CTA. IMD could reduce the rate of residual aneurysm and unanticipated vessel stenosis which demonstrated statistically significant advantages compared with aneurysm surgery without IMD. Conclusion IMD is a safe, easily performed, reliable, and valuable tool that is suitable for routine use in intracranial surgery, especially in complicated, large, and giant aneurysms with wide neck or without neck.