Introduction: Single-position (SP) circumferential spine surgery has evolved as a novel operative technique. The purpose of this study was to identify differences in intraoperative neurophysiological monitoring (IOM) event rates between SP lateral decubitus and prone-lateral patients during spine surgery.
Methods: Patients were stratified by operative positioning: Lateral decubitus (LD) and Prone Lateral (PL). IOM was performed using somatosensory evoked potentials (SSEPs), motor evoked potentials (MEPs), and electromyography (EMG) techniques. An abnormal event was defined as any confirmed loss of signal during the operative period in the anatomical distribution of the surgery. Means comparison tests and multivariable logistic regression analysis assessed differences between patient groups.
Results: 152 met inclusion criteria (93 LD & 59 PL). The majority were male (55.7%), mean age of 49.2 yrs and 2.0 levels fused and 18 (20.5%) undergoing an osteotomy. There was a significant difference in abnormal IOM event rates for patients who were in Lat (31%) vs PL (8%) positioning, p=0.012. Multivariable analysis revealed that PL patients were less likely to experience an abnormal IOM event than Lat patients (OR 0.232 [CI 0.060-0.905], p=0.035). This was seen in the saphenous, quadriceps and perineal sensory distributions.
Conclusion : Prone lateral positioning offers advantages over lateral decubitus with regards to decreased abnormal intraoperative neurophysiological events. This may potentially help with risk stratification in the future when assessing patients undergoing single position procedures.
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