Intraoperative monitoring of visual evoked potentials in patients undergoing transsphenoidal surgery for pituitary adenoma: a systematic review

Abstract

Background Transsphenoidal surgery is the gold standard for pituitary adenoma resection. Although rare, a serious complication of surgery is worsened vision post-operatively. Objective To determine whether, in patients undergoing transsphenoidal surgery for pituitary adenoma, intraoperative monitoring of visual evoked potentials (VEP) is a safe, reproducible, and effective technological adjunct in predicting postoperative visual function. Methods The PubMed and OVID platforms were searched between January 1993 and December 2020 to identify publications that (1) featured patients undergoing transsphenoidal surgery for pituitary adenoma, (2) used intraoperative optic nerve monitoring with VEP and (3) reported on safety or effectiveness. Reference lists were cross-checked and expert opinion sought to identify further publications. Results Eleven studies were included comprising ten case series and one prospective cohort study. All employed techniques to improve reliability. No safety issues were reported. The only comparative study included described a statistically significant improvement in post-operative visual field testing when VEP monitoring was used. The remaining case-series varied in conclusion. In nine studies, surgical manipulation was halted in the event of a VEP amplitude decrease suggesting a widespread consensus that this is a warning sign of injury to the anterior optic apparatus. Conclusions Despite limited and low-quality published evidence regarding intra-operative VEP monitoring, our review suggests that it is a safe, reproducible, and increasingly effective technique of predicting postoperative visual deficits. Further studies specific to transsphenoidal surgery are required to determine its utility in protecting visual function in the resection of complex pituitary tumours.

Superior Hypophyseal Artery Intraoperative Indocyanine Green Angiogram as a Predictor of Postoperative Visual Function After Endoscopic Endonasal Surgery

“…Previous studies have sought a better means for intraoperative prediction of postoperative visual function, but examinations of tools such as visual evoked potentials are limited and inconclusive. 13,14…”

“…Previous research has attempted to use intraoperative visual evoked potentials to assess optic function in real-time, but the results have remained inconclusive. 13,14 An intraoperative tool predicting the risk of postsurgical visual loss would aid in postoperative care and management because patients at risk for visual deficit can be monitored in the intensive care unit (ICU) and appropriately treated with vasopressors and corticosteroids.…”

Prediction of Post-operative Visual Deterioration Using Visual-Evoked Potential Latency in Extended Endoscopic Endonasal Resection of Craniopharyngiomas

“…To date, many clinical studies have explored and confirmed a good correlation between intraoperative VEP and post-operative visual function, but most of them are limited to the relationship between VEP amplitude changes and visual function (16)(17)(18)(19)(20), and VEP is reliable in predicting new visual damage at 50% alarm criteria (16,20). Previous studies have paid less attention to P100 latency in VEP, and none of them could summarize the threshold for the degree of P100 latency in VEP prolongation (21). In the present work, data from 180 eyes in 90 patients were analyzed, and 8.61% was determined as the threshold for the degree of P100 prolongation for predicting post-operative visual deterioration.…”

Pediatric craniopharyngioma with significantly increased intraoperative visual evoked potential amplitude and postoperative visual acuity improvement: a case report

“…Visual evoked potential (VEP) is an established modality that allows safe brain tumor resection and visual acuity preservation during surgery [1][2][3][4]. Additionally, VEP is essential in preserving visual function during endoscopic transsphenoidal surgery (ETS) for sellar and parasellar tumors located near the optic pathway [5,6].…”