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

Farizeh Jashek-Ahmed,Joan Grieve,Hani J Marcus,Neil L Dorward,Jarnail Bal,Brett Sanders,Ivan Cabrilo

doi:10.1186/s12883-021-02315-4

Abstract

BackgroundTranssphenoidal surgery is the gold standard for pituitary adenoma resection. Although rare, a serious complication of surgery is worsened vision post-operatively.ObjectiveTo 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.MethodsThe 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.ResultsEleven 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.ConclusionsDespite 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.

Highlights

Transsphenoidal surgery is the gold standard for pituitary adenoma resection, yet in one third of patients it is incomplete [1]
Further studies specific to transsphenoidal surgery are required to determine its utility in protecting visual function in the resection of complex pituitary tumours
The use of total intravenous anaesthesia (TIVA) [4, 5], the incorporation into the hardware of light-emitting diode (LED) technology [6,7,8] and adjuncts such as electroretinography (ERG) [6,7,8] and electroencephalography (EEG) [9] have attempted to overcome technical setbacks previously encountered in Visual-evoked potentials (VEP) neuromonitoring, enhancing the technique’s reproducibility and interpretability, and working to make it more reliable and easier to integrate into the operative workflow

Summary

Introduction

Transsphenoidal surgery is the gold standard for pituitary adenoma resection, yet in one third of patients it is incomplete [1]. The close relationship between the pituitary and the optic pathway implies that the benefits of Jashek‐Ahmed et al BMC Neurol (2021) 21:287 complete resection must be balanced against the risk of post-operative visual dysfunction. There are comparatively few reports of intraoperative VEP monitoring during transsphenoidal pituitary surgery despite the close relationship that this surgical approach maintains with the optic apparatus. Seeing the recent improvements in VEP monitoring technique facilitating its wider use, we sought to investigate the technique’s currently reported role during the far more common transsphenoidal procedure for pituitary adenoma. Transsphenoidal surgery is the gold standard for pituitary adenoma resection. A serious complication of surgery is worsened vision post-operatively

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Conclusion