# The predictive value of intraoperative visual evoked potential monitoring for postoperative visual outcomes following extended endoscopic endonasal resection of recurrent craniopharyngiomas

## TL;DR

This study shows that monitoring visual evoked potentials during surgery for recurrent craniopharyngiomas can predict postoperative visual dysfunction.

## Contribution

The study identifies a specific amplitude reduction threshold in VEPs as an early warning sign for visual outcomes.

## Key findings

- Eyes with postoperative visual dysfunction showed significantly greater amplitude reduction ratios in VEPs.
- A 36.59% reduction in N75-P100 amplitude was identified as a strong predictor of visual dysfunction.
- Abnormal N75-P100 changes were the sole independent predictor of postoperative visual dysfunction.

## Abstract

Recurrent craniopharyngiomas pose high risks of postoperative visual dysfunction (POVD) during surgery. The current study aimed to explore the application value of intraoperative visual evoked potential (VEP) monitoring during the extended endonasal endoscopic approach (EEEA) for recurrent craniopharyngiomas.

A total of 42 patients with recurrent craniopharyngiomas undergoing EEEA with VEP monitoring were analyzed. The amplitude reduction ratios of N75-P100 and P100-N145 were calculated, and their predictive values for POVD were evaluated using group comparisons, receiver operating characteristic (ROC) curve analysis, and binary logistic regression analysis.

POVD was observed in 8 eyes (8/84, 9.52%) from 7 patients (7/42, 16.67%). Eyes with POVD exhibited significantly greater N75-P100 and P100-N145 amplitude reduction ratios than those without (p < 0.001 and p = 0.002, respectively). The threshold values of the two ratios for predicting POVD were 36.59% (AUC 0.862, p < 0.001) and 36.65% (AUC 0.791, p=0.007), respectively. Multivariate analysis identified that abnormal N75-P100 change was the sole independent predictor of POVD (Odds ratio 9.257, 95% Confidence interval 1.124-76.263; p = 0.039).

Intraoperative VEP monitoring was particularly recommended for patients undergoing EEEA for recurrent craniopharyngiomas. A one-third reduction in N75-P100 amplitude was proposed as an early warning criterion for VEP monitoring in this patient population.