Intraoperative Neuromonitoring Changes Research Articles

Surgical management of complex post-tuberculous kyphosis among African patients: clinical and radiographic outcomes for a consecutive series treated at a single institution in West Africa.

Retrospective review of consecutive series. To assess the clinical and radiographic outcomes after surgical management of post-tuberculous kyphosis. Post-tuberculous (TB) kyphosis can lead to progressive pulmonary and neurological deterioration. Surgery is indicated to decompress neural elements and correct the spine deformity. Although posterior vertebral column resection (PVCR) has been established as the treatment of choice for severe TB kyphosis, there is paucity of studies on the clinical outcomes among patients treated in West Africa. Clinical and radiographic data of 57 patients (pts) who underwent surgical correction of post-TB kyphosis at a single site in West Africa between 2013 and 2018 (≥ 2-year follow-up in 36 pts, ≥ 1-year FU in 21 pts). Pre- and post-op SRS scores and radiographic outcomes were compared using Paired t test. 57 patients, 36M:21F. Mean age 19 (11-57years). 22/57 pts (39.3%) underwent pre-op halo gravity traction (HGT) for an average duration of 86days (8-144days). HGT pts had a higher baseline regional kyphosis (125.1 ± 20.9) compared to non-HGT pts (64.6 ± 31.8, p < 0.001). Post-HGT regional kyphosis corrected to 101.2 ± 23 (24° correction). 53 pts (92.9%) underwent posterior-only surgery and 4 (7.0%) combined anterior-posterior surgery. 39 (68.4%) had PVCR, 11 (19.3%) PSO, and 16 (28.1%) thoracoplasty. Intraoperative neuromonitoring (IOM) signal changes occurred in 23/57 pts (≈ 40%), dural tear in 5 pts (8.8%), pleural tear in 3 pts (5.3%), ureteric injury in 1 pt (1.7%), and vascular injury in 1 pt (1.7%). Post-op complications included four (7.0%) infection, three (5.3%) implant related, two (3.5%) radiographic (one PJK and one DJK), one (1.7%) neurologic, one (1.7%) wound problem, and two (3.5%) sacral ulcers. IOM changes were similar in the VCR (48.7%) and non-VCR (23.5%) pts, p > 0.05. Complication rates were similar among HGT and non-HGT groups. Significant improvements from baseline were seen in the average SRS Total and domains scores and radiographic measurements for patients who attained 2-year follow-up. PVCR ± HGT can provide safe and optimal correction in cases of severe post-TB kyphosis with good clinical and radiographic outcomes in underserved regions.

Do Intraoperative Neurophysiological Changes During Decompressive Surgery for Cervical Myeloradiculopathy Affect Functional Outcome? A Prospective Study.

Study Design:Prospective cohort.Objective:To investigate whether intraoperative neuromonitoring (IONM) positive changes affect functional outcome after surgical intervention for myeloradiculopathy secondary to cervical compressive pathology (cervical compressive myelopathy).Methods:Twenty-eight patients who underwent cervical spine surgery with IONM for compressive myeloradiculopathy were enrolled. During surgery motor-evoked potential (MEP) and somatosensory evoked potential (SSEP) at baseline and before and after decompression were documented. A decrease in latency >10% or an increase in amplitude >50% was regarded as a “positive changes.” Patients were divided into subgroups based on IONM changes: group A (those with positive changes) and group B (those with no change or deterioration). Nurick grade and modified Japanese Orthopaedic Association (mJOA) score were evaluated before and after surgery.Results:Nine patients (32.1%) showed improvement in MEP. The mean preoperative Nurick grade and mJOA score of group A and B were (2.55 ± 0.83 and 11.11 ± 1.65) and (2.47 ± 0.7 and 11.32 ± 1.24), respectively. The mean postoperative Nurick grade of groups A and B at 6 months was 1.55 ± 0.74 and 1.63 ± 0.46, respectively, and this difference was not significant. The mean postoperative mJOA score of groups A and B at 6 months was 14.3 ± 1.03 and 12.9 ± 0.98, respectively, and this difference was statistically significant (P = .011). Spearman correlation coefficient showed significant positive correlation between the IONM change and the mJOA score at 6 months postoperatively (r = 0.47; P = .01).Conclusion:Our study shows that impact of positive changes in MEP during IONM reflect in functional improvement at 6 months postoperatively in cervical compressive myelopathy patients.

Acute Neurological Deficits in Instrumented Pediatric Cervical Spine Fusions

Recipient: Bram Verhofste, MD Acute Neurological Deficits in Instrumented Pediatric Cervical Spine Fusions Bram P. Verhofste, MD1; Michael P. Glotzbecker, MD2; M Timothy Hresko, MD2; Patricia Miller, MS1; Craig M. Birch, MD1; Michael Troy, BS1; Nora P. O'Neill, BA1; Lawrence I. Karlin, MD2; John B. Emans, MD2; Mark R. Proctor, MD2; Daniel J. Hedequist, MD2, (1) Boston Children's Hospital, Boston, MA, (2) Boston Children's Hospital, Harvard Medical School, Boston, MA Introduction: Pediatric cervical deformity is a complex disorder often associated with neurological deterioration requiring cervical spine fusion. However, little literature exists on new perioperative neurologic deficits in children. This study describes new perioperative neurologic deficits in pediatric cervical spine instrumentation and fusion. Methods: A single-center review of pediatric cervical spine instrumentation and fusion during 2002-2018 was performed. Demographics, surgical characteristics, and neurological complications were recorded. Perioperative neurologic deficits were defined as the deterioration of preexisting neurologic function or the appearance of new neurologic symptoms. Results: A total of 184 cases (160 patients, 57% male) with an average age of 12.6 ±5.30 years were included. Instability (n=63) and deformity (n=41) were the most frequent indications. Syndromes were present in 39% (n=71). Eighty-seven (48%) children presented with preoperative neurologic deficits (16 sensory, 16 motor, and 55 combined deficits). A total of 178 (96.7%) cases improved or remained neurologically stable. New neurologic deficits occurred in six (3.3%) cases: three hemiparesis, one hemiplegia, one quadriplegia, and one quadriparesis (Table 1, Figure 1). Preoperative neurologic compromise was seen in four (67%) of these new deficits (three myelopathy, one sensory deficit) and five had complex syndromes. Three new deficits were anticipated with intraoperative neuromonitoring changes (p=0.025). Three (50.0%) patients recovered within six months and the child with quadriparesis is expected to make a complete recovery. Hemiplegia persisted in one patient and one child died due a complication related to the tracheostomy. No association was found between etiology (p=0.46), preoperative neurological symptoms (p=0.65), age (p=0.56), halo (p=0.41), EBL (p=0.09), levels fused (p=0.09), approach (p=0.07), or fusion location (p=0.37). Conclusion: An improvement of the preexisting neurologic deficit or stabilization of neurologic function was seen in 96.7% of children after cervical spine fusion. New or progressive neurologic deficits occurred in 3.3% of the patients and occurred more frequently in children with preoperative neurologic symptoms. Patients with syndromic diagnoses are at higher risk to develop a deficit, likely due to the severity of deformity and the degree of cervical instability. Long-term outcomes of new neurologic deficits are favorable and 50% experienced complete neurologic recovery within six months.

Preoperative CT Angiography Informs Instrumentation in Anterior Spine Surgery for Idiopathic Scoliosis

Introduction:The objective of this study is to evaluate whether the artery of Adamkiewicz localization with preoperative CT angiography influences anterior spinal instrumentation.Methods:Children with idiopathic scoliosis who underwent anterior instrumentation and with a preoperative CT angiography were evaluated retrospectively. Data included curve type, artery of Adamkiewicz level/laterality, surgical approach laterality, number of instrumented levels and segmental vessels ligated, intraoperative neuromonitoring changes, and postoperative neural complications.Results:Thirty-nine girls and eight boys (mean age 12 years [6.7 to 16.8 years]) were analyzed. Instrumented curves indicate 28 thoracic, 14 thoracolumbar, and seven double major. The artery of Adamkiewicz: T6 (left-1), T8 (left-1), T9 (left-4/right-2), T10 (left-11/right-4), T11 (left-4/right-4), T12 (left-1/right-2), L1 (left-2/right-1), and L2 (left-3/right-2). Four had bilateral dominant segmentals, whereas in nine patients, none was identified. T10 (32%) and left side (57%) were most frequent. On average, 7.1 (4 to 11) segmentals were ligated per case (total 355). Dominant vessels were ipsilateral to/within instrumentation levels in 30%.Discussion:In children with idiopathic scoliosis who underwent anterior instrumentation, the artery of Adamkiewicz was identified on the left in >50% and at T10 in 32%. In one-third of the patients, the artery was within intended surgical levels and resulted in instrumentation modification.

Radiologic Outcomes and Complication Analysis of the Posterior Vertebral Column Resection in the Treatment of Previously Operated Severe Kyphoscoliosis: A Retrospective Case Series

The aim of this study was to evaluate the radiologic outcomes and complication analysis of posterior vertebral column resection (PVCR) performed on previously operated patients with severe kyphoscoliosis (SK). Twelve patients (6 men and 6 women) with SK underwent PVCR. The mean age of the patients preoperatively was 16 years (range, 10-26 years). The mean follow-up period was 5.3 years (range, 2-7 years). Previous surgeries included posterior growth arrest in 3 patients, hemivertebrectomy in 4 patients, and posterior fusion in 5 patients. The sagittal plane parameters and coronal parameters were measured in the preoperative, in the early postoperative, and during the last follow-up stages. Complications were also noted. The mean thoracic scoliosis Cobb angle was 76.8° (range, 35°-142°) preoperatively, 37.8° (range, 5°-80°) early postoperatively, and 41.5° (range, 11°-80°) during the last follow-up (P < 0.0001). The mean thoracic kyphosis angle was 84.7° (range, 23°-132°) preoperatively, 50.3° (range, 25°-78°) early postoperatively, and 48.5° (range, 25°-80°) during the last follow-up (P= 0.0032). Complications occurred in 5 patients (41.7%); a hemothorax in 1 patient, rod fracture in 3 patients, and permanent neurologic deficit in 1 patient. Temporary loss of neuromonitoring motor evoked potentials developed in 2 patients during deformity correction. PVCR provides effective correction in patients with SK. However, expected surgical correction of a deformity may not always be achieved because of intraoperative neuromonitoring changes. Furthermore, PVCR can lead to a large number of major complications in patients with SK who have undergone previous spinal surgery.

A Study of Critical Events That Lead to Spinal Cord Injury and the Importance of Rapid Reversal of Surgical Steps in Improving Neurological Outcomes: A Porcine Model.

Porcine model. To quantify critical vascular and mechanical events that occur before and during an evolving spinal cord injury. Spinal cord injuries are one of the most devastating complications in spine surgery. Intraoperative neuromonitoring changes can occur as a secondary event of spinal cord compression and decrease in spinal cord blood flow (SCBF). Laser Doppler flowmetry has been well validated for measuring blood flow. Seventeen pigs were studied, 14 of which completed the experiment. Multilevel, midthoracic laminectomies were performed. Laser Doppler flowmetry electrodes were placed on the dura to measure SCBF. Spinal cord injury was induced by incremental balloon inflation in the epidural space. The animals were separated into two groups. After motor-evoked potential (MEP) loss, group A underwent medical interventions and then balloon decompression approximately 20 minutes later. Group B underwent immediate balloon decompression followed by medical interventions. After interventions, wake-up test was performed and computed tomography scan measured thoracic spinal canal volume. Median SCBF changes were seen 15.8 (5.4-25.1) minutes before MEP loss. However, the 20% threshold interval was often reached before. At the 20% threshold, median pressure was 7 psi, balloon volume was 0.5 cm, and 50% of the spinal canal was compromised. In group A, no pigs moved and all had pathology indicating ischemia. In group B, 9 of 10 were found to be moving their hind legs with 7 indicating ischemia. Compression spinal cord injury is the end of a cascade involving increasing intracanal pressure, decreasing canal volume, and hypoperfusion. Rapid relief of compression leads to MEP return. SCBF monitoring can detect ischemia preinjury, giving surgeons an opportunity for early intervention. 4.

Critical Limit of Lower-Extremity Lengthening in Total Hip Arthroplasty: An Intraoperative Neuromonitorization Study.

The effect of limb lengthening on neural structures was assessed with use of intraoperative neuromonitoring (IONM) during primary total hip arthroplasty (THA). The relationship between the critical limit of lengthening and anthropometric measurements was evaluated. Motor evoked potentials (MEPs) from the deep peroneal nerve (tibialis anterior muscle), tibial nerve (gastrocnemius muscle), and femoral nerve (quadriceps muscle), as well as somatosensory evoked potentials (SEPs) from the posterior tibial nerve, were recorded in 16 patients undergoing THA. Height, weight, the distance between the anterior superior iliac spine and the medial malleolus (ASIS-MM distance), and the total femoral length were measured preoperatively. Lower-extremity traction was performed after resection of the femoral head, and the amount of extremity lengthening was measured with use of an image intensifier. A maximum of 50% reduction in any one of the SEP or MEP amplitudes or a 10% increase in the SEP latency were considered to be indicative of the critical limit of lengthening. Initial IONM changes (indicating the safe limit of lengthening) and maximum allowed IONM changes (indicating the critical limit of lengthening) were reached in the deep peroneal nerve in all cases. The mean safe limit of lengthening (and standard deviation) was 14.9 ± 6.2 mm (3% relative to femoral length and 1.7% relative to ASIS-MM distance), whereas the critical limit of lengthening was exceeded at a mean of 22.4 ± 5.6 mm (5% relative to femoral length and 2.6% relative to ASIS-MM distance). When the critical limit was reached in the deep peroneal nerve, the mean decrease in MEP amplitudes was 27% (95% confidence interval [CI], 22.1% to 32.7%) for the tibial nerve and 12% (95% CI, 6.9% to 18.1%) for the femoral nerve. There was a positive correlation between critical lengthening and femoral length (r = 0.782; p < 0.001), ASIS-MM distance (r = 0.811; p < 0.001), and height (r = 0.835; p = 0.001). No correlation existed between the critical lengthening amount and the decrease in amplitude in the tibial and femoral nerves. The critical limit of nerve lengthening was directly correlated with anthropometric measurements. Nerve lengthening of 5% relative to femoral length and of 2.6% relative to ASIS-MM distance was found to be critical; however, these limits depended on the predetermined threshold values for IONM. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

P31. Intraoperative complications and neurologic changes following posterior thoracic corpectomies via a costotransversectomy type approach

BACKGROUND CONTEXT Iatrogenic cord injuries, dural tears, and pleural injuries are operative risks associated with thoracic corpectomies via costotransversectomy approaches (TCCA). Few studies have comprehensively described the rates of intra-operative complications including motor score changes, intraoperative neuromonitoring changes, dural tears, and pleural injuries. PURPOSE We seek to describe the rates and sequelae of changes to lower extremity motor score (LEMS), neuromonitoring signal changes, dural tears and pleural injuries in patients undergoing TCCA. STUDY DESIGN/SETTING Retrospective chart review conducted at a single academic referral center. PATIENT SAMPLE A total of 118 consecutive patients undergoing TCCA over a 10-year period with documented preoperative and post-operative motor examinations. OUTCOME MEASURES Outcomes included documented LEMS (out of 50) and intraoperative neuromonitoring changes. Pleural and dural injuries and subsequent treatment were assessed. METHODS Data were retrospectively collected from operative notes, intraoperative neuromonitoring reports, and the post-operative inpatient and outpatient clinical notes. Preoperative LEMS greater than or equal to 48 were considered intact. Post-operative LEMS were categorized into improved, unchanged or lower as compared to the preoperative scores. Categorical data was assessed with the Fisher's Exact test. Significance was set at p=0.05. RESULTS Lower extremity motor scores: Of the 118 patients, 68 were intact pre-operatively and 50 were not intact. Four percent of non-intact patients demonstrated a declining post-operative examination as compared to 14.7% of intact patients (p CONCLUSIONS Most patients undergoing TCCA procedures have unchanged or improved LEMS by discharge. Approximately 10% of patients had an initial decline in their LEMS with less than 3% of patients demonstrating lasting decline in neurologic status at final follow-up. Most neuromonitoring changes occurred at the time of corpectomy or graft/cage placement. Intraoperative pleural and dural injures during these procedures generally only require simple routine treatment. This information can be valuable in counseling patients regarding the risk of neurologic outcome, dural tear, and pleural injury following TCCA. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

P130. Intraoperative neuromonitoring findings are predictive of neurological outcomes after decompression for cervical spondylotic myelopathy

BACKGROUND CONTEXT Intraoperative Neuromonitoring (IONM) is frequently used by spine surgeons to predict emerging neurological insult and to provide functional feedback prior to development of irreversible neural injury. Despite its widespread use, however, it remains unclear whether various IONM changes are predictive of neurological outcomes in patients who undergo decompression surgery for cervical spondylosis with myelopathy (CSM). PURPOSE To evaluate the prognosticative ability of IONM changes for neurological outcomes after surgical decompression in patients with CSM. STUDY DESIGN/SETTING Retrospective evaluation of a prospectively enrolled cohort of patients who underwent surgery for CSM at the Ohio State University Wexner Medical Center. PATIENT SAMPLE A total of 39 patients were prospectively enrolled in a CSM trial at our institution and underwent decompression surgery between 2013-17. All patients with available intraoperative somatosensory evoked potential (iSSEP), motor evoked potential (iMEP), and spontaneous electromyography (iEMG) recordings as well as perioperative mJOA scores were included in the study. OUTCOME MEASURES The modified Japanese Orthopaedic Association (mJOA) scale evaluated at 1-year following surgery. METHODS Either univariate ANOVA with post hoc analysis (Student–Newman–Keuls) or t-tests were used to analyze DmJOA in relation to iSSEP, iMEP, and iEMG changes. RESULTS During surgery, iMEPs either improved, remained stable, or decreased in 5, 29 and 5 patients, respectively. iSSEPs improved, remained stable, or decreased in 1, 37 and 1 patient, respectively. Twenty-five patients showed spontaneous iEMG activity, which ultimately resolved in all cases. In patients in whom iMEP decreased, remained stable, or improved, mJOA improved by 1.3, 2.0, and 2.8 points 12 months after surgery, respectively. In contrast to iSSEP (p=0.58), iMEP changes and the presence/absence of iEMG activity during surgery were predictive of DmJOA at 12 months (p=0.02 and 0.007, respectively). CONCLUSIONS Decompressive surgery for CSM is generally associated with positive neurologic outcomes. Our findings suggest that patients in whom iMEPs improve potentially benefit the most, whilst those with iMEP decreases or spontaneous iEMG activity benefit the least. Whether IONM findings can prognosticate the degree of functional recovery after decompressive surgery for CSM will need to be confirmed in larger scale studies. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Perioperative acute neurological deficits in instrumented pediatric cervical spine fusions.

Pediatric cervical deformity is a complex disorder often associated with neurological deterioration requiring cervical spine fusion. However, limited literature exists on new perioperative neurological deficits in children. This study describes new perioperative neurological deficits in pediatric cervical spine instrumentation and fusion. A single-center review of pediatric cervical spine instrumentation and fusion during 2002-2018 was performed. Demographics, surgical characteristics, and neurological complications were recorded. Perioperative neurological deficits were defined as the deterioration of preexisting neurological function or the appearance of new neurological symptoms. A total of 184 cases (160 patients, 57% male) with an average age of 12.6 ± 5.30 years (range 0.2-24.9 years) were included. Deformity (n = 39) and instability (n = 36) were the most frequent indications. Syndromes were present in 39% (n = 71), with Down syndrome (n = 20) and neurofibromatosis (n = 12) the most prevalent. Eighty-seven (48%) children presented with preoperative neurological deficits (16 sensory, 16 motor, and 55 combined deficits).A total of 178 (96.7%) cases improved or remained neurologically stable. New neurological deficits occurred in 6 (3.3%) cases: 3 hemiparesis, 1 hemiplegia, 1 quadriplegia, and 1 quadriparesis. Preoperative neurological compromise was seen in 4 (67%) of these new deficits (3 myelopathy, 1 sensory deficit) and 5 had complex syndromes. Three new deficits were anticipated with intraoperative neuromonitoring changes (p = 0.025).Three (50.0%) patients with new neurological deficits recovered within 6 months and the child with quadriparesis was regaining neurological function at the latest follow-up. Hemiplegia persisted in 1 patient, and 1 child died due a complication related to the tracheostomy. No association was found between neurological deficits and indication (p = 0.96), etiology (p = 0.46), preoperative neurological symptoms (p = 0.65), age (p = 0.56), use of halo vest (p = 0.41), estimated blood loss (p = 0.09), levels fused (p = 0.09), approach (p = 0.07), or fusion location (p = 0.07). An improvement of the preexisting neurological deficit or stabilization of neurological function was seen in 96.7% of children after cervical spine fusion. New or progressive neurological deficits occurred in 3.3% of the patients and occurred more frequently in children with preoperative neurological symptoms. Patients with syndromic diagnoses are at higher risk to develop a deficit, probably due to the severity of deformity and the degree of cervical instability. Long-term outcomes of new neurological deficits are favorable, and 50% of patients experienced complete neurological recovery within 6 months.

Responding to Intraoperative Neuromonitoring Changes During Pediatric Coronal Spinal Deformity Surgery.

Study Design:Retrospective case study on prospectively collected data.Objectives:The purpose of this explorative study was: 1) to determine if patterns of spinal cord injury could be detected through intra-operative neuromonitoring (IONM) changes in pediatric patients undergoing spinal deformity corrections, 2) to identify if perfusion based or direct trauma causes of IONM changes could be distinguished, 3) to observe the effects of the interventions performed in response to these events, and 4) to attempt to identify different treatment algorithms for the different causes of IONM alerts.Methods:Prospectively collected neuromonitoring data in pre-established forms on consecutive pediatric patients undergoing coronal spinal deformity surgery at a single center was reviewed. Real-time data was collected on IONM alerts with >50% loss in signal. Patients with alerts were divided into 2 groups: unilateral changes (direct cord trauma), and bilateral MEP changes (cord perfusion deficits).Results:A total of 97 pediatric patients involving 71 females and 26 males with a mean age of 14.9 (11-18) years were included in this study. There were 39 alerts in 27 patients (27.8% overall incidence). All bilateral changes responded to a combination of transfusion, increasing blood pressure, and rod removal. Unilateral changes as a result of direct trauma, mainly during laminotomies for osteotomies, improved with removal of the causative agent. Following corrective actions in response to the alerts, all cases were completed as planned. Signal returned to near baseline in 20/27 patients at closure, with no new neurological deficits in this series.Conclusion:A high incidence of alerts occurred in this series of cases. Dividing IONM changes into perfusion-based vs direct trauma directed treatment to the offending cause, allowing for safe corrections of the deformities. Patients did not need to recover IONM signal to baseline to have a normal neurological examination.

A Novel Posterior Rod-Link-Reducer System Provides Safer, Easier, and Better Correction of Severe Scoliosis

Study DesignRetrospective review. ObjectivesTo compare the Cobb >75° scoliosis correction obtained using a novel Rod-Link-Reducer (RLR) system versus traditional corrective techniques (TCT) in patients with severe adolescent idiopathic scoliosis (AIS). Summary of Background DataCurrent implant strategies provide for good correction, especially for moderate curves; however, severe scoliosis continues to be challenging to obtain correction in a safe and effective manner. MethodsA novel correction device was developed so that two provisional rods are placed on the convex side of the scoliosis proximally and distally, which are then linked to an external reduction device termed the RLR. A retrospective analysis was performed to compare the RLR versus the TCT in patients with curve >75° with the diagnosis of AIS with respect to the radiographic outcomes, operative time, intraoperative blood loss, complications, and SRS-30 scores of a minimum 2-year follow-up. ResultsA total of 36 patients were evaluated (RLR-18, TCT-18). The data sets were similar for age, gender, coronal Cobb, curve flexibility, and follow-up period. The mean preoperative Cobb for the RLR group was 91.7° (76°–113°) and 91.8° (78°–108°) for the TCT group. The mean coronal Cobb correction rate was significantly greater for the RLR group (73.1% vs. 56.6%, p < .0001). The mean operative time was 74.8 minutes shorter in the RLR group (316.6 minutes vs. 391.4 minutes, p = .03). There were 2 late-developing infections and 3 intraoperative neuro-monitoring changes during the correction maneuvers in the TCT group compared with none in the RLR group (p = .02). ConclusionIn a matched cohort, the use of the RLR exhibited greater coronal Cobb correction, shorter operative time, and was less likely to have critical neuro-monitoring changes compared with the TCT group. The RLR provides safer and improved correction for severe curves without adding surgical risk. Level of EvidenceLevel III.

Technical Tips: A Checklist for Responding to Intraoperative Neuromonitoring Changes

ABSTRACTWhen changes occur in neurological responses during a surgical case, it is very important that all staff in the operating room (OR) understand their role in resolving or improving these conditions. Timely interventions are needed, and each personnel team is responsible for very specific tasks. Our intent was to cut down on confusion and delay by implementing a checklist that assigns tasks and designates a coordinator, so we incorporated the use of a checklist developed by Vitale et al. into our process for neuromonitoring cases. Staff members who used the checklist were surveyed to assess ease of use, understanding and perceptions about patient safety and case efficiency with the incorporation of the checklist. The post-implementation survey showed an increase in confidence and understanding in team responsibilities and workflow. Results showed ease of use and a perception of increased patient safety with no perceived decrease in surgery case efficiency.

The Effect of the Level of Training of the First Assistant on the Outcomes of Adolescent Idiopathic Scoliosis Surgery.

At academic medical centers, residents and fellows play an integral role as surgical first assistants in spinal deformity surgery. However, limited data exist on whether the experience level of the surgical assistant affects outcomes. We conducted a multicenter, multisurgeon study comparing perioperative and postoperative outcomes after adolescent idiopathic scoliosis (AIS) surgery for the same 11 surgeons who performed cases that were assisted by residents compared with cases that were assisted by fellows. Blood loss, operative time, duration of hospitalization, complication rates, Scoliosis Research Society (SRS)-22 questionnaire scores, and radiographic outcomes were compared between the 2 groups. We evaluated outcomes for 347 surgical procedures; 118 cases were assisted by residents and 229 were assisted by fellows. Preoperative radiographic and demographic parameters were not different between the groups. The resident group had significantly more estimated blood loss than the fellow group (939 compared with 762 mL, p = 0.02). Otherwise, the perioperative characteristics were similar between the groups, including the volume of the autologous blood recovery system product that was transfused, the operative time, and the occurrence of intraoperative neuromonitoring changes. Postoperatively, the percentage correction of the Cobb angle, the number of levels that had been fused, the number of days until the discharge criteria had been met, and the rate of major complications were similar between the groups. At the 2-year follow-up, the overall and subdomain SRS-22 questionnaire scores were not different between the groups, except that patients in the resident-assisted group had slightly worse pain scores than those in the fellow-assisted group (4.3 compared with 4.5, p = 0.01). The first assistant's level of training did not affect clinical or radiographic outcomes following AIS surgery. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Wednesday, September 26, 2018 1:00 PM – 2:00 PM Navigation and Intraoperative Monitoring: 45. Neuromonitoring signal changes in cervical spine surgery: when is it significant?

BACKGROUND CONTEXT Modern cervical spine surgeries utilizes intraoperative neuromonitoring (IONM) in the form of motor evoked potential (MEP), somatosensory evoked potential (SSEP) and electromyography (EMG). However, with a sensitivity ranging from 0% to 100% and specificity ranging from 27% to 100%, there is a need to differentiate between true and false positive signal changes to better supplement intraoperative management. PURPOSE To compare the incidence of neurological deficits in sustained, bimodal intraoperative neuromonitoring (MEP and SEP) signal drops to that of unimodal or transient changes in cervical spine surgeries. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE A total of 257 cases of cervical spine surgery with multimodal neuromonitoring in 3 hospitals in Singapore between 2013 and 2017. OUTCOME MEASURES Incidence of neurological deficits in 3 different patterns of neuromonitoring signal changes. Sensitivity and specifity of MEP and SSEP in cervical spine surgeries. METHODS A retrospective review of IONM and clinical records of all cervical spine surgeries in three hospitals between 2013 and 2017. The procedures were performed by fellowship trained spine surgeons and multimodal IONM was used in all cases. Clinical records were evaluated by two clinicians who were not involved in the patients' management. IONM records of MEP and SSEP were reviewed by a trained neurophysiology technologist. Results were grouped into three groups. In Group 0, there were unimodal signal drops that were transient and resolved back to baseline by the end of surgery. In Group 1, there were sustained unimodal signal changes while in Group 2, there were sustained drops in both the MEP and SSEP. RESULTS A total of 257 cases were reviewed and 207 cases were analyzed after exclusions. A total of 52/207 (25.1%) cases had IONM changes. A total of 10/207 (4.3%) of cases were in Group 0, while Group 1 had 35/207 (16.9%) of cases. 7/207 (3.4%) of cases were in Group 2. Group 0 and 1 had no neurological deficits, while in Group 2, 2/7 (28.6%) had neurological deficits. Both MEP and SSEP were 100% sensitive. SSEP had a specificity of 96.6%, while MEP had a lower specificity at 76.6%. CONCLUSIONS Our study shows that by grouping the signal changes into transient or sustained, and unimodal or bimodal, we are able to better predict which signal drops are significant, thereby allowing for improved intraoperative decision making. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

F116. Correlation of laryngeal adductor reflex, vocal CoMEPs, and vagus nerve mapping during thyroid surgery with immediate and long-term outcome: Description of two cases

Introduction The implementation of intraoperative neuromonitoring (IONM) during thyroid surgery has proven to place more emphasis on preserving neurological function, decreasing considerably unfavorable outcomes. Our purpose is to correlate the Laryngeal adductor reflex (LAR), vocal-CoMEPs and vagus-RLN nerve mapping IONM changes throughout thyroid surgery, with immediate and long-term outcome in two representative cases. Methods LAR, a novel method for assessing laryngeal and vagus nerve integrity, vocal-CoMEPs, and nerve mapping, were used for IONM. CoMEPs were elicited by TES (short trains of 5 stimuli of 0.5-ms; ISI of 2-ms; intensity up to 120-mA), and LAR by a single electrical stimulus of the laryngeal mucosa using electrodes attached to the ETT (of 0.1–1-ms; intensity up to 8-mA) on the contralateral side of the operative field. ETT-based electrodes were used to record both LAR and CoMEPs responses from vocal fold muscles. Facial-CoMEPs were elicited as a control parameter. RLN-vagus mapping was done using a hand-held monopolar stimulation probe. Videolaryngoscopy was used for initial intubation with tube position verification prior surgery. Significant changes in LAR amplitude responses were the critical parameters for IONM interpretation. Both patients underwent pre and postoperative direct laryngoscopy and thyroarytenoid (TA) EMG assessments. Results Case 1. – A 43-year-old female presented with a history of multinodular goiter. Total thyroidectomy was scheduled. Preoperative evaluation was normal. Bilateral LAR and vocal-CoMEPs responses were elicited at the onset of surgery. During transecting of the left-thyroid-gland, left vocal-CoMEPs and LAR responses were lost. Left RLN and vagus mapping did not elicit any response after the event. Postoperatively the patient presented with hoarseness. Laryngoscopic examination confirmed paralysis of the left vocal cord and left TA-EMG performed 4 weeks after surgery showed abnormal spontaneous activity; low amplitudes-polyphasic MUPs; and mildly decreased interference pattern, consistent with moderate left RLN dysfunction. Case 2. – A 63-year-old female patient who underwent total thyroidectomy for an intrathoracic multinodular goiter. Preoperative assessment was normal. LAR and vocal-CoMEPs responses were bilaterally elicited at the onset of surgery. During resection of the left thyroid lobe, left vocal-CoMEPs and LAR responses completely disappeared. Left RLN and vagus mapping did not elicit any response after the event. Postoperatively the patient presented with cough and hoarseness. The laryngoscopic examination confirmed paralysis of the left vocal cord and post-op left TA-EMG results were also consistent with moderate left RLN dysfunction. Conclusion There is a good correlation between LAR, vocal-CoMEPs and RLN-vagus mapping changes with immediate and long-term outcome in patients during thyroid surgery. LAR is a novel method for assessing laryngeal and vagus nerve integrity that can be useful for IONM during thyroid surgery.

The influence of anaesthesia on intraoperative neuromonitoring changes in high-risk spinal surgery

Abstract Background: The use of intraoperative neuromonitoring is a well-established method of detecting neurologic injuries during spine surgery. Anaesthesia, especially inhalational agents, influence motor evoked potential (MEP) monitoring. The aim of our study was to compare the effect of balanced anaesthesia (BA) (intravenous plus inhalational anaesthesia) and total intravenous anaesthesia (TIVA) on the incidence of intraoperative neuromonitoring changes, interventions performed and neurological outcomes of patients following high-risk spinal surgery. Methods: After Research and Ethics Board approval, a retrospective review of 155 patients who underwent spinal surgery with MEP was performed. Data were collected on changes in MEP and/or somatosensory evoked potential, interventions performed and neurological outcomes. Patients were divided into BA and TIVA groups and data were analysed. Results: A total of 152 patients were eligible for the study (mean age 54 ± 17, male: female 45:55). A BA technique was used in 62% and TIVA in 38%. Desflurane (&lt;0.5 minimum alveolar concentration [MAC]) was used in 85% BA cases. Intraoperative neuromonitoring changes occurred in 11.8% (18/152) of cases. There was no statistical difference in the incidence of monitoring changes between BA (78%) and TIVA (22%) groups (P = 0.197). Anaesthetic or surgical interventions were performed in 12 patients, with a resolution of changes in 50% (P = 0.455). All 5 patients with persistent MEP changes had worsening of existing neurological deficits postoperatively; 8 had transient MEP changes, and 2 experienced worsening of existing neurological deficits. Conclusions: We found that intraoperative neurophysiological monitoring can be performed with both BA (MAC &lt;0.5) and TIVA in high-risk spinal surgery with no statistical difference in the incidence of intraoperative monitoring changes.

Proper Responding Strategies to Neuromonitoring Alerts During Correction Step in Posterior Vertebral Column Resection Patients With Severe Rigid Deformities Can Reduce Postoperative Neurologic Deficits.

Retrospective study. To analyze the intraoperative neuromonitoring (IOM) changes in posterior vertebral column resection (PVCR) for severe rigid deformity patients, and describe our stepwise responding strategies. Obvious neurological deficit risk accompanied with PVCR correction has been emphasized repeatedly. The records of 46 patients who underwent PVCR achieved IOM were reviewed. IOM alerts triggered responding protocols: (1) exchange the convex corrective rod to concave stabilizing rod, (2) appropriate compression for spinal shortening, (3) reversed in situ rod bending, (4) translation technique and unisegmental derotation, (5) adjacent segmental resection. The overall scoliotic correction rate was 65.4% (from 112 ± 28.6 to 39 ± 13.4) and segmental kyphotic correction rate was 64.2% (from 101 ± 37.3 to 36 ± 19.2). During correction step, somatosensory-evoked potential warning (3) and somatosensory-evoked potential/transcranial motor-evoked potential warning (8) were detected in 11 patients (23.9%). Probable cause identification including rule out IOM technical factors, residual impingement, and if there was unstable spinal column (1), spinal cord excessive tension on concave side (3), and the excessive opposite spinal displacement between two aspects of resected area (7). After rod change (1), compression (2), bending (3), derotation (3), and adjacent resection (2), all IOM changes went to under warning criteria. All 11 patients revealed neurologically intact postoperatively. There was no difference of correction rate between IOMs alert or not. However, adult, extremely severe or sharp angular curves tend to be more common in IOM alert patients. As three-dimensional spinal column divided and relinked in PVCR, and the correction maneuvers were restricted on single dimension, inevitably resulted in spinal cord tension changes and spinal column opposite displacement. To timely identify them, prompt interventions should be performed, and even enlarge the resected area to reduce the abrupt turning tendency of the spinal cord. 5.

239 - Neurologic Complications May Occur During Any Stage of Extradural Spine Surgery: Intraoperative Neuromonitoring Findings and Outcomes in 107,447 Procedures

BACKGROUND CONTEXT: Intraoperative neuromonitoring (IONM) detects adverse changes in neurophysiologic function during surgery, affording the surgical team an opportunity to possibly reverse evolving injury. Little is known about the correlation between resolution of IONM changes during different stages of extradural spine surgery and postoperative neurologic outcome.

Intraoperative neuromonitoring loss in abnormal magnetic resonance imaging signal intensity from patients with cervical compressive myelopathy

PurposeOur objective of this study was to evaluate if cervical compressive myelopathy (CCM) patients with preoperative abnormal magnetic resonance imaging (MRI) might easily lead to intraoperative neuromonitoring (IONM) loss. MethodA consecutive series of 152 CCM patients who underwent cervical cord decompression were enrolled in this study between December 2013 and February 2017. All patients with abnormal MRI signal intensity were divided into 2 groups (group 1: T2-WIs hyperintensity; group 2: both T2-WIs hyperintensity and T1-WIs hypointensity). Relevant IONM changes were identified as significant transcranial motor evoked potentials (MEP) loss associated with surgical decompression of cervical cord. ResultsThere were 121 patients in group 1, and then 6 cases showed IONM degeneration; 31 patients in group 2, and then 13 cases showed IONM degeneration (6/121 versus 13/31, p=0.000). Moreover, one case presented transient new spinal deficits after surgery, no permanent spinal deficit in group 1; 5 cases presented transient new spinal deficits, 2 cases showed permanent spinal deficit in group 2. And in group 2 the MEP amplitude before and after decompression had significant difference (134μV±30.2 versus 65μV±26.2, *p<0.05). ConclusionOur results suggest that the IONM degenerations or postoperative spinal deficits are more likely to appear on patients with abnormal T2-WIs and T1-WIs. Appropriate and timely interventions are probably useful for IONM recovery.