{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,1]],"date-time":"2026-04-01T11:34:05Z","timestamp":1775043245123,"version":"3.50.1"},"reference-count":8,"publisher":"Scientific Scholar","content-domain":{"domain":["surgicalneurologyint.com"],"crossmark-restriction":true},"short-container-title":[],"abstract":"<jats:sec id=\"st1\">\n<jats:title>Background:<\/jats:title>\n<jats:p>The standard of care is to utilize intraoperative neurophysiological monitoring (IOM) of triggered electromyography (tEMG) during posterior lumbosacral instrumented-fusion surgery. IOM should theoretically signal misplacement of S1 screws into the neural L5\u2013S1 foramen or spinal canal, utilizing screw stimulation, and recording of the lower limb muscles and the anal sphincter. Here, we evaluated when and whether anterolateral S1 screw malposition could be detected by IOM\/tEMG during open posterior lumbosacral instrumented fusion surgery.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"st2\">\n<jats:title>Methods:<\/jats:title>\n<jats:p>tEMG, somatosensory-evoked potential (SSEP), and transcranial electrical motor-evoked potential (TcMEP) data were retrospectively reviewed from 2015 to 2017 during open posterior lumbosacral instrumented fusions. We utilized screw stimulation alert thresholds of &lt;14 mA (tEMG) and recorded from the lower extremity muscles and anal sphincter. Furthermore, all patients underwent routine postoperative computed tomography (CT) scans to confirm the screw location.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"st3\">\n<jats:title>Results:<\/jats:title>\n<jats:p>There were 106 S1 screws placed in 54 patients: 52 bilateral and 2 unilateral. In 6 patients (11.1%), 7 screws (6.6%) registered at low tEMG thresholds. In 1 patient, the postoperative CT scan documented external malposition of the screw despite no intraoperative IOM\/tEMG alert. When S1 misplaced screws were stimulated, the most sensitive muscle was the tibialis anterior; the sensitivity of the IOM\/tEMG was 87.5%, the specificity was 97.9%, the positive predictive value was 77.8%, and the negative predictive value was 98.9%. TcMEP and SSEP did not change during any of the operations. Notably, no patient developed a new neurological deficit.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"st4\">\n<jats:title>Conclusion:<\/jats:title>\n<jats:p>Anterolateral S1 screw malposition can be detected accurately utilizing IOM\/tEMG stimulation of screws. When alerts occur, they can largely be corrected by partially backing out the screw (e.g., a few turns) and\/ or changing the screw trajectory.<\/jats:p>\n<\/jats:sec>","DOI":"10.25259\/sni_4_2020","type":"journal-article","created":{"date-parts":[[2020,3,6]],"date-time":"2020-03-06T09:15:02Z","timestamp":1583486102000},"page":"42","update-policy":"https:\/\/doi.org\/10.25259\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Anterolateral S1 screw malposition detected with intraoperative neurophysiological monitoring during posterior lumbosacral fusion"],"prefix":"10.25259","volume":"11","author":[{"given":"Juan P. Cabrera","family":"Cousi\u00f1o","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Francisco","family":"Luna","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"M\u00e1ximo","family":"Torche","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sebasti\u00e1n","family":"Vigueras","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Esteban","family":"Torche","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guillermo","family":"Vald\u00e9s","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"10894","published-online":{"date-parts":[[2020,3,6]]},"reference":[{"key":"10.25259\/SNI_4_2020\/ref-1","doi-asserted-by":"crossref","first-page":"2780","DOI":"10.1097\/00007632-199412150-00008","article-title":"Stimulus-evoked EMG monitoring during transpedicular lumbosacral spine instrumentation. Initial clinical results","volume":"19","author":"Calancie","year":"1994","journal-title":"Spine (Phila Pa 1976)"},{"key":"10.25259\/SNI_4_2020\/ref-2","doi-asserted-by":"crossref","first-page":"S85","DOI":"10.1016\/j.otsr.2013.11.001","article-title":"Neurological risks in scheduled spinal surgery","volume":"100","author":"Garreau de Loubresse","year":"2014","journal-title":"Orthop Traumatol Surg Res"},{"key":"10.25259\/SNI_4_2020\/ref-3","doi-asserted-by":"crossref","first-page":"407","DOI":"10.1016\/j.jvs.2010.08.084","article-title":"Iatrogenic arterial injuries of spine and orthopedic operations","volume":"53","author":"Hans","year":"2011","journal-title":"J Vasc Surg"},{"key":"10.25259\/SNI_4_2020\/ref-4","doi-asserted-by":"crossref","first-page":"E2","DOI":"10.3171\/2014.1.FOCUS13525","article-title":"Accuracy of intraoperative computed tomography image-guided surgery in placing pedicle and pelvic screws for primary versus revision spine surgery","volume":"36","author":"Hsieh","year":"2014","journal-title":"Neurosurg Focus"},{"key":"10.25259\/SNI_4_2020\/ref-5","doi-asserted-by":"crossref","first-page":"S461","DOI":"10.1007\/s00586-012-2634-z","article-title":"L5 spinal nerve injury caused by misplacement of outwardly-inserted S1 pedicle screws","volume":"22","author":"Inoue","year":"2013","journal-title":"Eur Spine J"},{"key":"10.25259\/SNI_4_2020\/ref-6","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1097\/BSD.0000000000000561","article-title":"Intraoperative radiographic technique for visualization of bicortical or tricortical anteromedial sacral screw placement","volume":"31","author":"Jain","year":"2018","journal-title":"Clin Spine Surg"},{"key":"10.25259\/SNI_4_2020\/ref-7","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1186\/1749-799X-9-22","article-title":"Evidence-based support for S1 transpedicular screw entry point modification","volume":"9","author":"Kubaszewski","year":"2014","journal-title":"J Orthop Surg Res"},{"key":"10.25259\/SNI_4_2020\/ref-8","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1016\/S1047-9651(03)00106-2","article-title":"Electrophysiologic intraoperative monitoring for spine procedures","volume":"15","author":"Slimp","year":"2004","journal-title":"Phys Med Rehabil Clin N Am"}],"container-title":["Surgical Neurology International"],"original-title":[],"language":"en","link":[{"URL":"http:\/\/surgicalneurologyint.com\/anterolateral-s1-screw-malposition-detected-with-intraoperative-neurophysiological-monitoring-during-posterior-lumbosacral-fusion\/","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"http:\/\/surgicalneurologyint.com\/surgicalint-articles\/anterolateral-s1-screw-malposition-detected-with-intraoperative-neurophysiological-monitoring-during-posterior-lumbosacral-fusion\/","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2020,3,6]],"date-time":"2020-03-06T09:15:05Z","timestamp":1583486105000},"score":1,"resource":{"primary":{"URL":"http:\/\/surgicalneurologyint.com\/surgicalint-articles\/anterolateral-s1-screw-malposition-detected-with-intraoperative-neurophysiological-monitoring-during-posterior-lumbosacral-fusion\/"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,3,6]]},"references-count":8,"alternative-id":["10.25259\/SNI_4_2020"],"URL":"https:\/\/doi.org\/10.25259\/sni_4_2020","relation":{},"ISSN":["2152-7806"],"issn-type":[{"value":"2152-7806","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,3,6]]},"article-number":"42"}}