Risk factors for positioning-related somatosensory evoked potential changes in 3946 spinal surgeries


The goal of this study was to evaluate the risk factors associated with positioning-related SSEP changes (PRSC). The study investigated the association between 18 plausible risk factors and the occurrence of intraoperative PRSC. Risk factors investigated included demographic variables, comorbidities, and procedure related variables. All patients were treated by the University of Pittsburgh Medical Center from 2010 to 2012. We used univariate and multivariate statistical methods. 69 out of the 3946 (1.75%) spinal surgeries resulted in PRSC changes. The risk of PRSC was increased for women (p < 0.001), patients older than 65 years of age (p = 0.01), higher BMI (p < 0.001) patients, smokers (p < 0.001), and patients with hypertension (p < 0.001). No associations were found between PRSC and age greater than 80 years, diabetes mellitus, cardiovascular disease, and peripheral vascular disease. Three surgical situations were associated with PRSC including abnormal baselines (p < 0.001), patients in the “superman” position (p < 0.001), and patients in surgical procedures that extended over 200 min (p = 0.03). Patients with higher BMIs and who are undergoing spinal surgery longer than 200 min, with abnormal baselines, must be positioned with meticulous attention. Gender, hypertension, and smoking were also found to be risk factors from their odds ratios.

This is a preview of subscription content, log in to check access.

Fig. 1


  1. 1.

    Schwartz DM, et al. Prevention of positional brachial plexopathy during surgical correction of scoliosis. J Spinal Disord. 2000;13(2):178–82.

    Article  CAS  PubMed  Google Scholar 

  2. 2.

    Sestokas AK, Schwartz DM, Hilibrand AS, Vaccaro AR, Bose B, Li M, Albert TJ. Neurophysiological identification of position-induced neurologic injury during anterior cervical spine surgery. J Clin Monit Comput. 2006;20:437–44.

    Article  PubMed  Google Scholar 

  3. 3.

    Kombos T, et al. Impact of somatosensory evoked potential monitoring on cervical surgery. J Clin Neurophysiol. 2003;20(2):122–8.

    Article  PubMed  Google Scholar 

  4. 4.

    Anastasian ZH, et al. Evoked potential monitoring identifies possible neurological injury during positioning for craniotomy. Anesth Analg. 2009;109(3):817–21.

    Article  PubMed  PubMed Central  Google Scholar 

  5. 5.

    Mills WJ, et al. Somatosensory evoked potential monitoring during closed humeral nailing: a preliminary report. J Orthop Trauma. 2000;14(3):167–70.

    Article  CAS  PubMed  Google Scholar 

  6. 6.

    Hickey C, et al. Intraoperative somatosensory evoked potential monitoring predicts peripheral nerve injury during cardiac surgery. Anesthesiology. 1993;78(1):29–35.

    Article  CAS  PubMed  Google Scholar 

  7. 7.

    Parks BJ. Postoperative peripheral neuropathies. Surgery. 1973;74(3):348–57.

    CAS  PubMed  Google Scholar 

  8. 8.

    Richmond MN, Sawyer RJ, Hickey JD, Jarrratt JA. Peripheral nerve injuries associated with anaesthesia. Anaesthesia. 2000;55:980–91.

    Article  PubMed  Google Scholar 

  9. 9.

    Brummett CM, Welch MB, Welch TD, Tremper KK, Shanks AM, Guglani P, Mashour GA. Perioperative peripheral nerve injuries: a retrospective study of 380,680 cases during a 10-year period at a single institution. Anesthesiology. 2009;111(3):490–7.

    Article  PubMed  Google Scholar 

  10. 10.

    Barnette R, Kamel I. Positioning patients for spine surgery: avoiding uncommon position-related complications. World J Orthop. 2014;5(4):425–43.

    Article  PubMed  PubMed Central  Google Scholar 

  11. 11.

    Seyfer AE, et al. Upper extremity neuropathies after cardiac surgery. J Hand Surg. 1985;10(1):16–9.

    Article  CAS  Google Scholar 

  12. 12.

    Kroll DA, et al. Nerve injury associated with anesthesia. Anesthesiology. 1990;73(2):202–7.

    Article  CAS  PubMed  Google Scholar 

  13. 13.

    Larson SJ, Sances A. Evoked potentials in man. Neurosurgical applications. Am J Surg. 1966;111(6):857–61.

    Article  CAS  PubMed  Google Scholar 

  14. 14.

    McCallum JE. Electrophysiologic monitoring of spinal cord function during intraspinal surgery. Surg Forum. 1975;26:469–71.

    CAS  PubMed  Google Scholar 

  15. 15.

    Nash CL Jr, et al. Spinal cord monitoring during operative treatment of the spine. Clin Orthop Relat Res. 1977;126:100–5.

    Google Scholar 

  16. 16.

    Dawson EG, et al. Spinal cord monitoring. Results of the Scoliosis Research Society and the European Spinal Deformity Society survey. Spine. 1991;16(8):361–4.

    Google Scholar 

  17. 17.

    Jellish WS, et al., Somatosensory evoked potentials help prevent positioning-related brachial plexus injury during skull base surgery, Otolaryngol Head Neck Surg 2013;149(1):168–73.

    Article  PubMed  Google Scholar 

  18. 18.

    Labrom RD, et al. Clinical usefulness of somatosensory evoked potentials for detection of brachial plexopathy secondary to malpositioning in scoliosis surgery. Spine. 2005;30(18):2089–93.

    Article  PubMed  Google Scholar 

  19. 19.

    Lenke LG, Daubs MD, Cheh G, Stobbs G, Bridwell KH. Adult spinal deformity surgery: complications and outcomes in patients over age 60. Spine 2007;32(20):2238–44.

    Article  PubMed  Google Scholar 

  20. 20.

    Puno RM, Carreon L, Dimar JR, Glassman SD, Johnson JR. Perioperative complications of posterior lumbar decompression and arthrodesis in older adults. J Bone Joint Surg Am 2003;85(11):2089–92.

    Article  PubMed  Google Scholar 

  21. 21.

    Reiter GT, Telfeian AE, Durham SR, Marcotte P. Spine surgery in morbidly obese patients. J Neurosurg. 2002;97(1):20–4.

    PubMed  Google Scholar 

  22. 22.

    Shabat S, Gepstein R, Arinzon ZH, Berner Y, Catz A, Folman Y. Does obesity affect the results of lumbar decompressive spinal surgery in the elderly? Clin Orthop Relat Res. 2004;426:138–44.

    Article  Google Scholar 

  23. 23.

    Bagan B, Patel N, Vadera S, Maltenfort MG, Deutsch H, Vaccaro AR, Harrop J, Sharan A, Ratliff JK. Obesity and spine surgery: relation to perioperative complications. J Neurosurg Spine. 2007;6(4):291–7.

    Article  PubMed  Google Scholar 

  24. 24.

    Glow JA, Chung I, Dimopoulos V, Walid S, Smisson HF, Johnston KW, Robinson JS, Grigorian AA. Upper-limb somatosensory evoked potential monitoring in lumbosacral spine surgery: a prognostic marker for position-related ulnar nerve injury. Spine J. 2009;9(4):287–95.

    Article  PubMed  Google Scholar 

  25. 25.

    Teng Y, Jiang J, Fan Z, Khan S, Xia Y. Does obesity affect the surgical outcome and complication rates of spinal surgery? A meta-analysis., Clin Orthop Relat Res. 2014;472(3):968–75.

    Article  PubMed  Google Scholar 

  26. 26.

    Kassasm AB, Thirumala PD, Habeych M, Wichman K, Chang YF, Gardner P, Prevedello D, Snyderman C, Carrau R, Crammond DJ, Balzer J. Somatosensory evoked potential monitoring during endoscopic endonasal approach to skull base surgery: analysis of observed changes. Neurosurgery. 2011;69.

  27. 27.

    Balzer JR, Rose RD, Welch WC, Sclabassi RJ. Simultaneous somatosensory evoked potential and electromyographic recordings during lumbosacral decompression and instrumentation. Neurosurgery. 1998;42(6):1318–24 (discussion 1324–5).

    Article  CAS  PubMed  Google Scholar 

  28. 28.

    Chen ZY, Wong HK, Chan YH. Variability of somatosensory evoked potential monitoring during scoliosis surgery. J Spinal Disord Tech. 2004;17(6):470–6.

    Article  PubMed  Google Scholar 

  29. 29.

    York DH, Chabot RJ, Gaines RW. Response variability of somatosensory evoked potentials during scoliosis surgery. Spine. 1987;12(9):864–76.

    Article  CAS  PubMed  Google Scholar 

  30. 30.

    Cunningham EJ, Bond R, Mayberg MR, Warlow CP, Rothwell PM. Risk of persistent cranial nerve injury after carotid endarterectomy. J Neurosurg. 2004;101(3):445–8.

    Article  PubMed  Google Scholar 

  31. 31.

    Greenland S, Christensen R. Data augmentation priors for Bayesian and semi-Bayes analyses of conditional-logistic and proportional-hazards regression. Stat Med. 2001;20(16):2421–8.

    Article  CAS  PubMed  Google Scholar 

  32. 32.

    Sullivan SG, Greenland S. Bayesian regression in SAS software. Int J Epidemiol. 2013;42(1):308–17.

    Article  PubMed  Google Scholar 

  33. 33.

    Greenland S. Invited commentary: variable selection versus shrinkage in the control of multiple confounders. Am J Epidemiol. 2008;167(5):523–9 (discussion 530-1).

    Article  PubMed  Google Scholar 

  34. 34.

    Lee LA. Perioperative visual loss and anesthetic management. Curr Opin Anaesthesiol. 2013;26:375–81.

    Article  PubMed  Google Scholar 

  35. 35.

    Zhao H, Kamel I, Koch SA, Brister N, Barnette RE. The use of somatosensory evoked potentials to determine the relationship between intraoperative arterial blood pressure and intraoperative upper extremity position-related neurapraxia in the prone surrender position during spine surgery: a retrospective analysis. Anesth Analg. 2016;122(5):1423–33.

    Article  PubMed  Google Scholar 

  36. 36.

    Schurrer ME, Alvine FG. Postoperative ulnar-nerve palsy. Are there predisposing factors? J Bone Joint Surg Am. 1987;69:255–9.

    Article  PubMed  Google Scholar 

  37. 37.

    Drum ET, Kamel IR, Koch SA, Whitten JA, Gaughan JP, Barnette RE, Wendling WW. The use of somatosensory evoked potentials to determine the relationship between patient positioning and impending upper extremity nerve injury during spine surgery: a retrospective analysis. Anesth Analg. 2006;102:1538–42.

    Article  PubMed  Google Scholar 

  38. 38.

    Winter RB, Faciszewski T, Lonstein JE, Denis F, Johnson L. The surgical and medical perioperative complications of anterior spinal fusion surgery in the thoracic and lumbar spine in adults: a review of 1223 procedures. Spine. 1995;20(14):1592–1599.

    Article  PubMed  Google Scholar 

  39. 39.

    O’Sullivan AJ. Does oestrogen allow women to store fat more efficiently? A biological advantage for fertility and gestation. Obes Rev. 2009;10(2):168–77.

    Article  CAS  PubMed  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Parthasarathy D. Thirumala.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Melachuri, S.R., Balzer, J.R., Melachuri, M.K. et al. Risk factors for positioning-related somatosensory evoked potential changes in 3946 spinal surgeries. J Clin Monit Comput 33, 333–339 (2019). https://doi.org/10.1007/s10877-018-0148-x

Download citation


  • Position-related changes
  • Intraoperative monitoring
  • Somatosensory evoked potentials