The value of intraoperative indocyanine green angiography in microvascular decompression for hemifacial spasm to avoid brainstem ischemia

Abstract

Purpose: Despite being rarely reported, ischemic insults resulting from compromising small brainstem perforators following microvascular decompression (MVD) remain a potential devastating complication. To avoid this complication, we have been using indocyanine green (ICG) angiography intraoperatively to check the flow within the small brainstem perforators. We aim to evaluate the safety and usefulness of ICG videoangiography in MVD.

Methods: We extracted retrospective data of patients who received ICG videoangiography from our prospectively maintained database for microvascular decompression. We noted relevant data including demographics, offending vessels, operative technique, outcome, and complications.

Results: Out of the 438 patients, 15 patients with a mean age (SD) of 53 ± 10.5 years underwent intraoperative ICG angiography. Male:female was 1:1.14. The mean disease duration prior to surgery was 7.7 ± 5.3 years. The mean follow-up (SD) was 50.7 ± 42.0 months. In 14 patients, the offending vessel was an artery, and in one patient, a vein. Intraoperative readjustment of the Teflon pledget or sling was required in 20% (3/15) of the cases. No patient had any sort of brainstem ischemia. Eighty percent of the patients (12/15) experienced complete resolution of the spasms. 86.7% (13/15) of the patients reported a satisfactory outcome with marked improvement of the spasms. Three patients experienced slight hearing affection after surgery, which improved in two patients later. There was no facial or lower cranial nerve affection.

Conclusion: Intraoperative ICG is a safe tool for evaluating the flow within the brain stem perforators and avoiding brainstem ischemia in MVD for hemifacial spasm.

Keywords: Brainstem ischemia; Brainstem perforators; Hemifacial spasm; Indocyanine green videoangiography; Microvascular decompression; Sling decompression technique.

Fig. 1

Preoperative MR imaging with TOF (left) and CISS (right) axial images showing a compression of the facial nerve root exit zone (arrow) by AICA (A) and VA (VA)

Fig. 2

Intraoperative images. A Severe compression of the facial nerve by a dilated VA (VA), VIII (vestibulocochlear nerve), and A (AICA). B Endoscopic inspection after the elevation of the VA shows an additional compression of the facial REZ by AICA (A) and VIII (vestibulocochlear nerve). C Tiny perforator (P) running over VA (VA). D Decompression of the VA by sling which was fixed to the dura with a Yasargil mini clip

Fig. 3

Sketch illustrating the sling decompression/vessel transposition technique of the vertebral artery (blue arrow) using a microvascular clip attached to a pocket of the dura of the skull base (blue star). The endangered perforating artery is referred to with a green arrow

Fig. 4

Microscopic and intraoperative indocyanine green angiography images over time. A The small perforating artery (arrow) looked somewhat stretched after the transposition of the VA (VA) by the Gortex sling (VIII, vestibulocochlear nerve). B and C Preadjustment time sequence of ICG angiography images showing a delayed filling of the perforator (arrow) compared to VA. Initially, the perforator is still dark although VA is already bright. Only in the late image, the perforator and VA and other vessels are bright. D reduced stretch on the perforator (arrow) after the release of the sling. E and F Postadjustemt time sequence images of ICG angiography showed a timely filling of the perforator (arrow) compared to VA