Intraoperative neurophysiological monitoring for Lumbar Spinal Instrumentation [Neurosurgery Wiki]

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====== Intraoperative neurophysiological monitoring for Lumbar Spinal Instrumentation ======

see also [[Intraoperative Neurophysiological Monitoring in Spine Surgery]].
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Multimodal [[intraoperative neurophysiologic monitoring]] (IONM) can be utilized as an adjunct to [[lumbar spinal instrumentation]] in order to aid with avoidance of neurologic complications. The most commonly utilized modalities include [[Somatosensory evoked potential]]s,[[motor evoked potential]]s, and [[electromyography]]. Somatosensory-evoked potentials (SSEPs) allow for continuous assessment of the dorsal columns of the spinal cord and are therefore most useful during procedures with a posterior approach to the cervical and thoracic spine. Motor-evoked potentials (MEPs) and electromyography (EMG) can be applied intermittently to assess motor nerve function. The utility of each individual modality can be largely dependent on the surgical approach. Approaches to lumbar spinal instrumentation can be generally categorized as anterior, lateral, and posterior. For lateral approaches, electromyography can be helpful in identifying neural structures crossing the surgical field to prevent injury. In posterior and anterior approaches, somatosensory-evoked potentials and motor-evoked potentials can be used to assess nerve injury during and after maneuvers for decompression and instrumentation. Additionally, during the placement of pedicle screws, direct stimulation with triggered electromyography can be used to detect the pedicle cortex's breach. The efficacy of intraoperative neuromonitoring is dependent on prompt and accurate recognition of changes in signals. This is then followed by accurate recognition of the cause for these changes and appropriate responses by the surgeon, anesthesiologist, and monitoring personnel to correct the change
((Hofler RC, Fessler RG. Intraoperative Neuromonitoring and Lumbar Spinal Instrumentation: Indications and Utility. Neurodiagn J. 2021 Mar;61(1):2-10. doi: 10.1080/21646821.2021.1874207. PMID: 33945449.))
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Although IONM is commonly used during [[spinal deformity]] in the modern era, its use in degenerative lumbar surgery, especially in uncomplicated procedures, remains controversial
((Alemo S, Sayadipour A. Role of intraoperative neurophysiologic monitoring in lumbosacral spine fusion and instrumentation: a retrospective study. World Neurosurg. 2010 Jan;73(1):72-6; discussion e7. doi: 10.1016/j.surneu.2009.04.024. Epub 2009 Aug 7. PMID: 20452872.)).

Supporters of IONM point out its value in detecting spinal nerve root injuries with high sensitivity and specificity, especially in revision and instrumented fusions cases
((Hamilton DK, Smith JS, Sansur CA, Glassman SD, Ames CP, Berven SH, Polly DW Jr, Perra JH, Knapp DR, Boachie-Adjei O, McCarthy RE, Shaffrey CI; Scoliosis Research Society Morbidity and Mortality Committee. Rates of new neurological deficit associated with spine surgery based on 108,419 procedures: a report of the scoliosis research society morbidity and mortality committee. Spine (Phila Pa 1976). 2011 Jul 1;36(15):1218-28. doi: 10.1097/BRS.0b013e3181ec5fd9. PMID: 21217448.)).

Although numerous studies have supported the use of IONM in lumbar fusion surgery, it is still unclear whether the improved detection of crisis events intraoperatively translates to a decreased rate of postoperative neurological deficits
((Weiss DS. Spinal cord and nerve root monitoring during surgical treatment of lumbar stenosis. Clin Orthop Relat Res. 2001 Mar;(384):82-100. doi: 10.1097/00003086-200103000-00011. PMID: 11249183.)).