Skip to main content
  • The Predictive Role of Intra-Operative Visual Evoked Potentials (VEP) in Visual Improvement After Endoscopic Pituitary Tumor Resection: Description and Validation of a Method

    Final Number:

    Jeffrey Schwartz MD; Raj K Shrivastava MD; Barbara Oudheusden RN; Svetlana Lenina MD

    Study Design:

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2016 Annual Meeting

    Introduction: : Intraoperative manipulation during endoscopic resection of pituitary tumors poses potential risk in postoperative visual acuity. This study proposes a method of accurate intraoperative monitoring of Visual Evoked Potentials (VEPs)and its role in predicting visual function outcomes.

    Methods: Intraoperative VEPs were monitored for 42 resections from a single surgical team. Quantitative method for VEP was developed and implemented whereby photic stimuli was directed through ultra-bright light emitting diode (LED) goggles. VEP from cortical areas were measured from six pairs of electrode sensors placed on the patient’s scalp. 100 readings was summed as a single action potential. Changes in VEP amplitude and latency in excess of 50% were considered significant. Comprehensive retrospective review was performed including patient demographics, comorbidities, and tumor characteristics. Pre and post operative visual information was obtained from ophthalmology records; Patients were stratified as experiencing deteriorations in VEPs that did not restore to baseline (n=4), deteriorations in VEPs that did restore to baseline (n=6), no change in VEPs (n=31), and improvement in VEPs (n=1).

    Results: Correlation between VEP changes and post-operative visual fields were measured through univariate ordered logistic regression. Improved intraoperative VEP measurements were associated odds ratio of visual field improvement of 3.15 (95% CI: 1.15-8.59). Specifically, changes in VEP amplitude were positively associated with visual field improvement with odds ratio of 4.35 (OR: 1.29-14.7) while changes in VEP latency were not significantly associated with visual field outcomes. No association was observed between VEPs and other patient or tumor characteristics

    Conclusions: Changes in VEP amplitude during endoscopic pituitary tumor resection correlates with surgical manipulation specifically to the optic nerve. Intraoperative VEP monitoring can serve an important role in preventing postoperative visual field loss. The predictive value of VEPs correlates with extended post-operative follow-up. These findings may further provide insight into neurophysiologic optic changes that occur during surgery

    Patient Care: The use of Visual Evoked Potentials (VEP) during complex endoscopic pituitary surgery allows for safer surgery and allows the surgeon the ability to

    Learning Objectives: By conclusion of this session, participants should be able to :1) Understand the Role of Visual Evoked Potentials (VEP) in Neurosurgery 2) Discuss the Indications for VEP monitoring in complex pituitary Surgery 3) Discuss the Neurophysiological implications of VEP changes during surgery and its role in visual function

    References: References 1. Benedicic M, Bosnjak R. Intraoperative monitoring of the visual function using cortical potentials after electrical epidural stimulation of the optic nerve. Acta Neurochir (Wien). 2011;153(10):1919-1927. 2. Benedicic M, Bosnjak R. Optic nerve potentials and cortical potentials after stimulation of the anterior visual pathway during neurosurgery. Doc Ophthalmol. 2011;122(2):115-125. 3. Black PM, Zervas NT, Candia GL. Incidence and management of complications of transsphenoidal operation for pituitary adenomas. Neurosurgery. 1987;20(6):920-924. 4. Bosnjak R, Benedicic M. Direct epidural electrical stimulation of the optic nerve: a new method for intraoperative assessment of function. J Neurosurg. 2008;109(4):647-653. 5. Brelen ME, Vince V, Gerard B, Veraart C, Delbeke J. Measurement of evoked potentials after electrical stimulation of the human optic nerve. Invest Ophthalmol Vis Sci. 2010;51(10):5351-5355. 6. Cedzich C, Schramm J, Fahlbusch R. Are flash-evoked visual potentials useful for intraoperative monitoring of visual pathway function? Neurosurgery. 1987;21(5):709-715. 7. Cedzich C, Schramm J, Mengedoht CF, Fahlbusch R. Factors that limit the use of flash visual evoked potentials for surgical monitoring. Electroencephalogr Clin Neurophysiol. 1988;71(2):142-145. 8. Celesia GG. Anatomy and physiology of visual evoked potentials and electroretinograms. Neurol Clin. 1988;6(4):657-679. 9. Chacko AG, Babu KS, Chandy MJ. Value of visual evoked potential monitoring during trans-sphenoidal pituitary surgery. Br J Neurosurg. 1996;10(3):275-278. 10. Chung SB, Park CW, Seo DW, Kong DS, Park SK. Intraoperative visual evoked potential has no association with postoperative visual outcomes in transsphenoidal surgery. Acta Neurochir (Wien). 2012;154(8):1505-1510. 11. Cohen AR, Cooper PR, Kupersmith MJ, Flamm ES, Ransohoff J. Visual recovery after transsphenoidal removal of pituitary adenomas. Neurosurgery. 1985;17(3):446-452. 12. Ebersold MJ, Quast LM, Laws ER, Jr., Scheithauer B, Randall RV. Long-term results in transsphenoidal removal of nonfunctioning pituitary adenomas. J Neurosurg. 1986;64(5):713-719. 13. Goto T, Tanaka Y, Kodama K, Kusano Y, Sakai K, Hongo K. Loss of visual evoked potential following temporary occlusion of the superior hypophyseal artery during aneurysm clip placement surgery. Case report. J Neurosurg. 2007;107(4):865-867. 14. Harding GF, Bland JD, Smith VH. Visual evoked potential monitoring of optic nerve function during surgery. J Neurol Neurosurg Psychiatry. 1990;53(10):890-895. 15. Holder GE. Pattern electroretinography in patients with delayed pattern visual evoked potentials due to distal anterior visual pathway dysfunction. J Neurol Neurosurg Psychiatry. 1989;52(12):1364-1368. 16. Holder GE, Bullock PR. Visual evoked potentials in the assessment of patients with non-functioning chromophobe adenomas. J Neurol Neurosurg Psychiatry. 1989;52(1):31-37. 17. Hussain SS, Laljee HC, Horrocks JM, Tec H, Grace AR. Monitoring of intra-operative visual evoked potentials during functional endoscopic sinus surgery (FESS) under general anaesthesia. J Laryngol Otol. 1996;110(1):31-36. 18. Jayaraman M, Ambika S, Gandhi RA, Bassi SR, Ravi P, Sen P. Multifocal visual evoked potential recordings in compressive optic neuropathy secondary to pituitary adenoma. Doc Ophthalmol. 2010;121(3):197-204. 19. Kamada K, Todo T, Morita A, et al. Functional monitoring for visual pathway using real-time visual evoked potentials and optic-radiation tractography. Neurosurgery. 2005;57(1 Suppl):121-127; discussion 121-127. 20. Kamio Y, Sakai N, Sameshima T, et al. Usefulness of intraoperative monitoring of visual evoked potentials in transsphenoidal surgery. Neurol Med Chir (Tokyo). 2014;54 Suppl 3:606-611. 21. Klistorner A, Crewther DP, Crewther SG. Temporal analysis of the topographic ERG: chromatic versus achromatic stimulation. Vision Res. 1998;38(7):1047-1062. 22. Kodama K, Goto T, Sato A, Sakai K, Tanaka Y, Hongo K. Standard and limitation of intraoperative monitoring of the visual evoked potential. Acta Neurochir (Wien). 2010;152(4):643-648. 23. Lorenz R, Heider W. [Retinal diseases as a cause of increased latency in the visual evoked cortical potential]. Klin Monbl Augenheilkd. 1990;196(1):17-20. 24. Luo Y, Regli L, Bozinov O, Sarnthein J. Clinical utility and limitations of intraoperative monitoring of visual evoked potentials. PLoS One. 2015;10(3):e0120525. 25. Neuloh G. Time to revisit VEP monitoring? Acta Neurochir (Wien). 2010;152(4):649-650. 26. Ota T, Kawai K, Kamada K, Kin T, Saito N. Intraoperative monitoring of cortically recorded visual response for posterior visual pathway. J Neurosurg. 2010;112(2):285-294. 27. Sasaki T, Itakura T, Suzuki K, et al. Intraoperative monitoring of visual evoked potential: introduction of a clinically useful method. J Neurosurg. 2010;112(2):273-284. 28. Sato A. Interpretation of the causes of instability of flash visual evoked potentials in intraoperative monitoring and proposal of a recording method for reliable functional monitoring of visual evoked potentials using a light-emitting device. J Neurosurg. 2016:1-10. 29. Tobimatsu S, Celesia GG. Studies of human visual pathophysiology with visual evoked potentials. Clin Neurophysiol. 2006;117(7):1414-1433. 30. Tu Y, Hung YS, Hu L, Huang G, Hu Y, Zhang Z. An automated and fast approach to detect single-trial visual evoked potentials with application to brain-computer interface. Clin Neurophysiol. 2014;125(12):2372-2383. 31. Wenzel D, Brandl U, Beck JD, Cedzich C, Albert F. Visual evoked potentials in tumors from orbita to occipital lobe in childhood. Neurosurg Rev. 1988;11(3-4):279-286. 32. Wiedemayer H, Fauser B, Sandalcioglu IE, Armbruster W, Stolke D. Observations on intraoperative monitoring of visual pathways using steady-state visual evoked potentials. Eur J Anaesthesiol. 2004;21(6):429-433.

We use cookies to improve the performance of our site, to analyze the traffic to our site, and to personalize your experience of the site. You can control cookies through your browser settings. Please find more information on the cookies used on our site. Privacy Policy