Efficacy of intraoperative neuromonitoring (IONM) and intraoperative indocyanine green videoangiography (ICG-VA) during unruptured anterior choroidal artery aneurysm clipping surgery

Abstract

Objective: The aim of this study was to investigate the efficacy of intraoperative indocyanine green videoangiography (ICG-VA) and intraoperative neuromonitoring (IONM) to prevent postoperative ischemic complications during microsurgical clipping of unruptured anterior choroidal artery (AChA) aneurysms.

Methods: We retrospectively reviewed the clinical and radiological records of all patients who had undergone microsurgical clipping for unruptured AChA aneurysms at our institution between April 2001 and December 2019. We compared the postoperative complication rate of the group for which intraoperative ICG-VA and IONM were utilized (group B; n=324) with that of the group for which intraoperative ICG-VA and IONM were not utilized (group A; n=72).

Results: There were no statistically significant differences in demographic data between the two groups. Statistically significant differences were observed in the rate of overall complications (p=0.014) and postoperative ischemic complications related to AChA territory (p=0.039). All the cases (n=4) in group B who had postoperative infarctions related to AChA territory showed false-negative results of intraoperative ICG-VA and IONM.

Conclusions: Preserving the patency of the AChA is essential to minimize postoperative complications. Intraoperative monitoring tools including ICG-VA and IONM can greatly contribute to lowering complication rates. However, their pitfalls and false-negative results should always be considered.

Keywords: Evoked potentials; False-negative reactions; Indocyanine green; Intracranial aneurysm; Microsurgery; Treatment outcome.

Fig. 1.

Images of a patient who underwent microsurgical clipping for an unruptured left anterior choroidal artery (AChA) aneurysm using a straight clip. (A) Preoperative transfemoral cerebral angiography (TFCA) showing the left AChA (black arrowhead). (B) Preoperative TFCA 3-dimensional image showing an unruptured left AChA aneurysm (white arrowhead). (C) Intraoperative indocyanine green videoangiography (ICG-VA) showing patent flow of left AChA after clipping. The left internal carotid artery (white arrow), the AChA (white arrowhead), and the clip (asterisk) are shown. (D) Postoperative diffusion-weighted magnetic resonance imaging (DW-MRI) showing an acute infarction in the left posterior limb of the internal capsule (red arrowheads). (E) The left AChA is not visible on postoperative TFCA. (F) Postoperative TFCA 3-dimensional image showing complete obliteration of the aneurysm. Note the atherosclerotic change of the parent artery and the small filling defect (white arrow) near the clip blade. This may represent vessel wall kinging or a dislodged atheroma causing obstruction of the distal flow. (G) No significant MEP changes were observed during the surgery. MEP, motor evoked potential