Elsevier

Spine Deformity

Volume 7, Issue 1, January 2019, Pages 132-140
Spine Deformity

Case Series
Intraoperative Neuromonitoring During Adult Spinal Deformity Surgery: Alert-Positive Cases for Various Surgical Procedures

https://doi.org/10.1016/j.jspd.2018.05.015Get rights and content

Abstract

Study Design

Retrospective study.

Objectives

To analyze intraoperative neuromonitoring (IONM) alerts in various surgical procedures and clarify incidences and causes of IONM alarms in consecutive adult spinal deformity (ASD) surgeries.

Summary of Background Data

ASD surgery has a high neurologic complication rate. IONM may play a role in identifying and preventing neurologic complications.

Methods

This study included 275 consecutive ASD patients treated by posterior corrective fusion who had been followed up for more than two years. We divided the patients into 1) the PCO group: multiple posterior column osteotomies; and 2) the 3CO group: three-column osteotomy including pedicle subtraction osteotomy and vertebral column resection. We set a 70% amplitude reduction as the alarm point for transcranial electrical stimulation motor-evoked potentials (Tc-MEPs) using 32-channel IONM.

Results

The PCO and 3CO groups included 162 and 113 cases, respectively. IONM revealed 32 cases (11.6%) of Tc-MEP alerts, 10.4% in the PCO group, and 13.2% in the 3CO group. Postoperative follow-ups revealed 15 cases (5.5%) of new neurologic deficits, 4.9% in the PCO group, and 6.2% in the 3CO group. Most IONM alarms in the PCO group appeared at the time of rod rotation maneuvers, and 88.9% of alarms were selective for MEP decrease. In contrast, IONM alarms in the 3CO group appeared at the time of spinal shortening, and 80% were global MEP decreases. Immediately after the alarm, neurologic deficits might be rescued by foraminal decompression after rod rotation and by adjusting the length of spinal shortening. Overall, more than 50% of cases with IONM alerts were rescued by intraoperative additional management.

Conclusion

IONM reduced the incidence of neurologic complications in ASD surgery. Spinal surgeons should recognize the type of muscle derivation and respond to such alerts by performing appropriate corrections reflecting the mechanism underlying the neural damage.

Level of Evidence

Level IV.

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

References (29)

  • Y. Yamato et al.

    A Japanese nationwide multicenter survey on perioperative complications of corrective fusion for elderly patients with adult spinal deformity

    J Orthop Sci

    (2017)
  • C. Schizas et al.

    Neurophysiological changes during shortening osteotomies of the spine

    Spine

    (2014)
  • F. Schwab et al.

    Adult scoliosis: prevalence, SF-36, and nutritional parameters in an elderly volunteer population

    Spine

    (2005)
  • F. Schwab et al.

    Radiographical spinopelvic parameters and disability in the setting adult spinal deformity

    Spine

    (2013)
  • S.D. Glassman et al.

    Correlation of radiographic parameters and clinical symptoms in adult scoliosis

    Spine

    (2005)
  • G. Li et al.

    Adult scoliosis in patients over sixty-five years of age: outcomes of operative versus nonoperative treatment at a minimum two-year follow-up

    Spine

    (2009)
  • J.S. Smith et al.

    Risk-benefit assessment of surgery for adult scoliosis: an analysis based on patient age

    Spine

    (2011)
  • K.H. Bridwell et al.

    Does treatment (nonoperative and operative) improve the two-year quality of life in patients with adult symptomatic lumbar scoliosis: a prospective multicenter evidence-based medicine study

    Spine

    (2009)
  • T.J. Wilson-Holden et al.

    Efficacy of intraoperative monitoring for pediatric patients with spinal cord pathology undergoing spinal deformity surgery

    Spine

    (1999)
  • S.D. Glassman et al.

    The impact of perioperative complications on clinical outcome in adult deformity surgery

    Spine

    (2007)
  • E.D. Thuet et al.

    Validity and reliability of intraoperative monitoring in pediatric spinal deformity surgery

    Spine

    (2010)
  • J.S. Smith et al.

    Prospective multicenter assessment of perioperative and minimum 2-year postoperative complication rates associated with adult spinal deformity surgery

    J Neurosurg Spine

    (2016)
  • V. Deletis

    Basic methodological principles of multimodal intraoperative monitoring during spine surgeries

    Eur Spine J

    (2007)
  • A.A. Gonzalez et al.

    Intraoperative neurophysiological monitoring during spine surgery: a review

    Neurosurg Focus

    (2009)
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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.

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