Effectiveness of intraoperative visual evoked potential in avoiding visual deterioration during endonasal transsphenoidal surgery for pituitary tumors
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Postoperative visual function is a major concern in transsphenoidal surgery (TSS). Although several reports have demonstrated the importance of visual evoked potential (VEP) monitoring during TSS, the usefulness of VEP monitoring have been controversial because of its reproducibility. Efficacy of VEP was analyzed in 20 consecutive cases of patients who underwent endoscopic endonasal TSS surgery. We adapted a high-power light-emitting diode stimulator with electroretinography using venous anesthesia. In addition, we used black shield patch and braided codes to obtain reproducible VEP amplitudes. Stable and reproducible VEP waveforms were obtained in 38 of 39 eyes (97.4%) before surgery. Fifteen eyes had deteriorated VEP amplitude during operation, and nine eyes had improved VEP amplitude at the end of surgery, and six eyes had not improved VEP amplitude. But no postoperative visual impairment was observed in all cases by temporary halting the surgical manipulation when the VEP was deteriorated. In conclusion, VEP monitoring could be a warning sign to avoid postoperative visual dysfunction. We recommend VEP as a routine monitoring in TSS.
KeywordsVEP Parasellar tumor Visual function
The authors are grateful to Mr. Shoto Yamada (Division of Clinical Engineering, Sapporo Medical University Hospital) for their technical support and observation of VEP changes during surgery. Their sincere cooperation has guaranteed the safety of our surgery.
Compliance with ethical standards
Conflicts of interest
The authors declare that they have no conflict of interest.
This study was approved by the Institutional Review Board of Sapporo Medical University.
Written informed consent was obtained from each patient in accordance with the local ethical guidelines.
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