Accuracy of indocyanine green videoangiography in predicting visual outcomes for anterior skull base surgeries, compared to intraoperative visual evoked potential: a pilot explorative study

Introduction: 

Preserving the microcirculation of the optic nerve (ON) during surgical decompression is crucial, yet there is no dependable intraoperative predictor of visual outcomes. This study examines the use of indocyanine green videoangiography (ICG-VA) as a potential predictor, comparing its effectiveness with intraoperative visual evoked potential (VEP).

Methods: 

We analyzed 13 patients with various perichiasmatic pathologies. Each underwent enhanced MRI, CT scans, detailed ophthalmological examinations, and VEP. Five control patients were included, presumed to have normal pial support post-aneurysmal clipping. Indocyanine green (ICG) was administered at 0.2 mg/kg via peripheral venous access after a rapid injection of 10 mL of 0.9% NaCl before and after tumor resection, using flow analysis software (Flow 800, Carl Zeiss Co.). We meticulously measured the intervals for ICG’s appearance in the internal carotid artery (ICA) and the pial circulation of the optic nerve as well as the full saturation of both before and after resection.

Results: 

The study included 13 patients and 5 controls (mean age: cases 55.30 ± 15.2 years; controls 57.8 ± 2.38, p < 0.05). Twelve patients had preoperative visual field impairment, with 10 showing postsurgical improvement. Prolonged P100 latency in VEPs was noted in 11 cases and 3 controls (case: 9.81 ± 13.11 ms; control: 5.9 ± 8.33 ms). Mean improvement in peak time of the optic nerve relative to the ipsilateral ICA was 0.82 ± 2.32 s post-resection (controls: 0.45 ± 0.87 s, p < 0.05). VEP yielded 60% sensitivity, 50% specificity, and 85.7% positive predictive value. ICG-VA demonstrated lower sensitivity (44%) but 100% specificity and positive predictive value. ROC analysis showed greater discrimination for ICG-VA (AUC = 0.790) than for VEP measures. No ICG-related complications occurred.

Conclusion: 

ICG-VA of the optic nerve is a promising modality for predicting visual outcomes compared with VEP. Moreover, it could provide more details on the ON vasculature, which would help preserve it during tumor resection. However, additional research, including randomized trials and data, is required to establish a significant difference.