Case SeriesIntraoperative Neuromonitoring During Adult Spinal Deformity Surgery: Alert-Positive Cases for Various Surgical Procedures
Introduction
In aging developed countries, adult spinal deformity (ASD) places an increasing burden on elderly patients as well as on health care systems by causing disability and reducing health-related quality of life (HRQOL) [1], [2], [3]. Surgical treatments for ASD offer radiographic and HRQOL outcomes that are superior to nonoperative treatments [4], [5], [6], but these procedures are often complex and may carry high risks of neurologic complications [7], [8], [9], [10], which directly affect patient recovery, hospitalization lengths, and the risk of prolonged or potentially permanent morbidity. The complications can vary considerably because of factors including surgical approach, use of osteotomies, and the patient’s precise pathology. Intraoperative neuromonitoring (IONM) is a highly effective tool for predicting postoperative neurologic complications. Recent reports have shown that IONM can reduce neurologic deterioration and reliably detect intraoperative nerve injuries [11], [12]. IONM includes monitoring of somatosensory-evoked potentials, transcranial motor-evoked potentials (Tc-MEPs), spinal cord MEPs, spontaneous (ie, continuous) electromyography, and triggered electromyography. Tc-MEP monitoring is regarded as the most sensitive to complication risks and has been reported to exhibit nearly 100% sensitivity and specificity, but its high sensitivity can relatively frequently produce false positives, which hinder surgery [13], [14], [15]. Previous studies had reported the utility of Tc-MEP monitoring during ASD surgeries, but few studies have investigated the mechanisms underlying different complications and how they depend on correction maneuvers or the use of osteotomies. We therefore aimed to assess the mechanisms underlying the neurologic complications detected by IONM in various surgical procedures.
Section snippets
Patients
Our study protocol was approved by our university hospital’s institutional review board and all patients provided written informed consent. We consecutively recruited ASD patients who underwent posterior corrective spinal fusion surgery at our institution between March 2010 and March 2015. All cases were followed for at least two years. We defined ASD as the presence of at least one of the following indicators: degenerative or idiopathic scoliosis with coronal plane spinal curvature greater
Results
A total of 275 patients (mean age 63.4 years, 52 male and 223 female) were included in this study. Most patients were female (81.1%). The pathologies included 92 cases of degenerative scoliosis (33.5%), 49 cases of degenerative kyphosis (17.8%), 46 cases of adult idiopathic scoliosis (16.7%), 50 vertebral fractures (18.2%), 23 patients with Parkinson disease (8.4%), 12 with failed back surgery syndrome (4.4%), and 3 with postinfection deformity (1.1%). There were 162 and 113 patients in the PCO
Case 1
A 69-year-old woman with degenerative kyphoscoliosis underwent spinal corrective surgery with multiple PCOs (Fig. 1). A Tc-MEP alert from her left quadriceps muscle occurred during a rod rotation, and an L4 pediculectomy was performed because the left L4 nerve root was impinged at the pedicle’s medio-inferior portion. After this intervention, the Tc-MEP amplitude gradually recovered. She exhibited no PNMD and was considered a rescue case (Fig. 2).
Case 2
A 57-year-old man in a wheelchair who had a
Discussion
Recent studies have reported that the incidence of neurologic complications in ASD surgery ranges from 2% to 17.8% [8], [10], [17]. We found that the incidence of severe neurologic deficits in patients with ASD was 5.5%. It is well recognized that 3COs carry a greater risk of complications in ASD surgery because of their complexity, the exposure of neural tissues, and spinal cord shortening [8], [18], [19], [20], [21], [22], [23], [24], but complex adult reconstructive surgeries often
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2024, Journal of Orthopaedic ScienceCitation Excerpt :The alarm point for postoperative motor deficit has been defined as decrease in amplitude of ≥70% from baseline [17,18]. Yoshida et al. reported that distraction accompanied by rod rotation caused partial Tc-MEP deterioration, whereas spinal cord ischemia caused global Tc-MEP deterioration [3]. Compression also caused partial or global waveform decrease depending on the damaged area (nerve root or spinal cord).
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Author disclosures: GY (none), TH (none), YY (none), SK (none), TB (none), SO (other from Medtronic Fofamor Danek Inc, Japan Medical Dynamic Marketing Inc., and Meitokukai Jyuzen Memorial Hospital, outside the submitted work), HA (none), YM (none), HU (none), TY (none), DT (grants from Medtronic Sofamor Danek, Inc., Japan Medical Dynamic Marketing, Inc., and Meitoku Medical Institute Jyuzen Memorial Hospital, outside the submitted work), YM (none).
IRB approval was obtained for this study before enrollment.