Significant change or loss of intraoperative monitoring data: A 25-year experience in 12,375 spinal surgeries

Barry L. Raynor, Joseph D. Bright, Lawrence G. Lenke, Ra'Kerry K. Rahman, Keith H. Bridwell, K. Daniel Riew, Jacob M. Buchowski, Scott J. Luhmann, Anne M. Padberg

Research output: Contribution to journalArticlepeer-review

80 Scopus citations


STUDY DESIGN.: Retrospective. OBJECTIVE.: The purpose of this study was to report the spectrum of intraoperative events responsible for a loss or significant change in intraoperative monitoring (IOM) data. SUMMARY OF BACKGROUND DATA.: The efficacy of spinal cord/nerve root monitoring is demonstrated in a large, single institution series of patients, involving all levels of the spinal column (occiput to sacrum) and all spinal surgical procedures. METHODS.: Multimodality IOM included somatosensory-evoked potentials, descending neurogenic-evoked potentials, neurogenic motor-evoked potentials, and spontaneous and triggered electromyography. A total of 12,375 patients who underwent surgery for spinal pathology between January 1985 and December 2010 were reviewed. There were 59.3% female patients (7178) and 40.7% male patients (5197). Procedures by spinal level were as follows: cervical 29.7% (3671), thoracic/thoracolumbar 45.4% (5624), and lumbosacral 24.9% (3080). Age at the time of surgery was as follows: older than 18 years, 72.7% (242/8993) and younger than 18 years, 27.3% (144/3382). A total of 77.8% (9633) patients underwent primary surgical procedures and 22.2% (2742) patients underwent revision surgical procedures. RESULTS.: A total of 406 instances of IOM data change/loss occurred in 386 of 12,375 (3.1%) patients. Causes for data degradation/loss included the following: instrumentation (n = 131), positioning (n = 85), correction (n = 56), systemic (n = 49), unknown (n = 24), and focal spinal cord compression (n = 15). Data loss/change was seen in revision (6.1%/167 patients) surgical procedures more commonly than in primary procedures (2.3%/219 patients; P < 0.0001). Data improvement was demonstrated by 88.7% (n = 360) after intervention versus 11.3% (n = 46) with no improvement in IOM data. One patient with improved data after intervention versus 14 with no improvement despite intervention had a permanent neurological deficit (P < 0.0001). CONCLUSION.: IOM data identified 386 (3.1%) patients with loss/degradation of data in 12,375 spinal surgical procedures. Fortunately, in 93.3% of patients, intervention led to data recovery and no neurological deficits. Reduction from a potential (worst-case scenario) 3.1% (386) of patients with significant change/loss of IOM data to a permanent neurological deficit rate of 0.12% (15) patients was achieved (P < 0.0001), thus confirming efficacy of IOM.

Original languageEnglish
Pages (from-to)E101-E108
Issue number2
StatePublished - Jan 15 2013


  • intraoperative monitoring
  • neurological defi cit
  • revision spinal surgery
  • spinal surgery


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