Methodology analysis of flash visual evoked potential and its preliminary application in intraoperative monitoring during operation of sellar region tumors

Objective To analyze the methodology parameters of intraoperative monitoring of flash visual evoked potential (F-VEP) and to explore its application value in the operation of sellar region tumors. Methods The clinical data of 117 patients admitted to Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University from May 2018 to August 2019 were retrospectively analyzed. A total of 86 patients with intraductal space-occupying lesions were enrolled as A group (112 eyes) for the study of intraoperative F-VEP parameters. The stable parameters obtained from the parameter study were applied to 31 patients with sellar region tumors (B group, 62 eyes). All patients underwent tumor resection and intraoperative F-VEP monitoring under general intravenous anesthesia. F-VEP amplitudes under various electrode channels and different stimulus frequencies (0.7-1.2 Hz) were compared. Results In the A group, at any stimulation frequencies, the amplitude between N75 and P100 wave (A1) of O2-Fz channel and Oz-Fz channel were significantly higher than those of O1-Fz channel (all P<0.05). At various stimulus frequencies within the range of 0.7-1.0 Hz, the amplitude of A2 of O2-Fz channel and Oz-Fz channel was significantly higher than those of O1-Fz channel (all P<0.05). In any electrode channel, A1 obtained at various stimulus frequencies within the range of 0.7-1.2 Hz did not vary significantly, while A2 at the frequency of 0.7 Hz was significantly higher than that at any other frequency (all P<0.05). In the B group, the stable F-VEP waveform was obtained in 61 eyes with an extraction rate of 98.4% (61/62). There was no change in F-VEP waveform in 19 patients in the B group, of which 13 had the same visual function as that before operation, and 6 of them had improved visual function. In the B group, among the 12 patients with reversible F-VEP waveform, 4 had the same visual function as that before surgery, 7 had improved visual function, and only 1 had decreased visual function. Conclusions After selecting appropriate stimulus parameters, stable and reliable F-VEP waveform can be obtained during operation. By means of preliminary application of F-VEP monitoring in sellar region tumor surgery, it has been preliminarily confirmed that intraoperative F-VEP monitoring could be used to predict the prognosis of postoperative visual function in patients. Key words: Brain Neoplasms; Monitoring, intraoperative; Evoked potentials, visual; Sellar region; Prognosis