Neuromonitoring Changes Research Articles

Power versus manual pedicle tract preparation: a multi-center study of early adopters.

Retrospective cohort, multicenter. A single surgeon study demonstrated that pedicle tract preparation with power tools was associated with lower fluoroscopy times and revision rates compared to manual tools, while maintaining patient safety. Our purpose was to determine the safety of power-assisted pedicle tract preparation by early adopters of this technology. Retrospective review comparing patients that underwent posterior spinal fusion by seven pediatric spine surgeons at six institutions between January 1, 2008 and August 31, 2019. The manual pedicle tract preparation used a pedicle awl. Power tract preparation used a flexible 2.0-2.4mm drill bit, followed by a larger drill bit or a reamer. All screws were inserted with power technique. In the manual tract preparation group, 9424 screws were placed in 585 cases. In the power tract preparation group, 22,209 screws were placed in 1367 cases. Seven patients (7/1952; 0.36%; 95% CI: 0.14-0.74%) had 11 mal-positioned screws (11/31,633; 0.03%; 95% CI: 0.017-0.062%). Seven screws (7/9424; 0.07%; 95% CI: 0.030-0.15%) were in the manual cohort and four (4/22,209; 0.02%; 95% CI: 0.0049-0.046%) were in the power cohort. There were significantly more revisions per screw in the manual cohort (p = 0.02). However, there were not significantly more revisions per patient in the manual cohort (manual: 0.5%, 3/585 vs. power: 0.3%, 4/1,367; p = 0.43). Of these seven, three patients (3/585; 0.5%; 95% CI: 0.1-1.5%) experienced neurologic injury or neuro-monitoring changes requiring screw removal in the manual cohort, and 1 patient (1/1,367, 0.07%; 95% CI: 0.002-0.4%) in the power cohort (p = 0.08). Three additional patients underwent revision in the power cohort: 1 for an asymptomatic lateral breech, 1 for a spinal headache/medial breech that developed after an MVA, and 1 for an iliac vein injury during pedicle tract preparation. This is the first multi-center study examining power pedicle preparation. Overall, 99.9% of pedicle screws placed with power pedicle preparation did not have complications or revision. Equivalent patient safety was demonstrated compared to manual technique. III.

Ponte osteotomies in a matched series of large AIS curves increase surgical risk without improving outcomes.

The routine use of Ponte osteotomies in adolescent idiopathic scoliosis (AIS) surgery is controversial with conflicting data for coronal plane correction and little analysis in the sagittal plane. The objective of this study was to analyze the efficacy of Ponte osteotomies in large curve AIS. A single institution, prospectively-collected series of consecutive AIS patients who had Ponte osteotomies (P cohort) was directly matched to patients with no Pontes (NP cohort) by age, gender, Lenke classification, surgeon, coronal, and sagittal Cobb angles. The radiographic review included adjusted values using a 3D-derived published formula for preoperative T5-T12 kyphosis. Patient-reported outcomes (PROs) were assessed with the SRS-30 and Spinal Appearance Questionnaire (SAQ). There were 68 patients (34/cohort) with minimum 2-year follow-up with no differences between P and NP cohorts in age, preoperative coronal Cobb (74.5° vs 70.8°), flexibility index, measured or 3D-adjusted T5-T12 kyphosis. Rod material/diameter, fusion levels, blood loss, and operative time did not differ, but implant density was higher in the P group (1.53 vs 1.31, p < 0.001). The P group had 7.9% greater coronal Cobb correction (66.6% vs 58.7%, p < 0.003) without difference in final Cobb angles (24.7° vs. 29.1°, p = 0.052). There were no differences in measured or adjusted T5-T12 kyphosis in the sagittal plane. The P group had a 15% rate of critical intraoperative neuromonitoring changes versus 0% in the NP group (p = 0.053). At follow-up, there were no differences in scoliometer measurements or any domain of SRS-30 or SAQ scores. In this first reported matched series of AIS patients, Ponte osteotomies provide small radiographic gains in the coronal plane with no improvement in the sagittal plane and no change in truncal rotation. There was a higher risk of critical intraoperative neuromonitoring changes, and no benefits in patient-reported outcomes. This calls into question the routine use of Ponte osteotomies in AIS, even for curves averaging 70 degrees. II.

A novel posterior multiple screws distraction reducer system versus anterior release, posterior internal distraction, and subsequent spinal fusion for severe scoliosis

PurposeWe previously reported anterior release, posterior internal distraction, and subsequent spinal fusion (ARPIDF) for the correction of severe scoliosis with a satisfactory correction rate. However, surgical procedures were completed in 2–3 stages. Here we compare Cobb angle of ≥90° in scoliosis correction between a novel posterior multiple screws distraction reducer (MSDR) system and ARPIDF.MethodsThirty-six patients with severe scoliosis treated by MSDR or ARPIDF (n = 18 in both groups). We retrospectively analyzed and compared outcome measures between the two groups over a minimum follow-up duration of 2 years. The following variables were compared between the two groups: age at surgery, sex, etiology, flexibility of the main thoracic curve, number of fused segments and screws, operation time, estimated blood loss, hospitalization time, follow-up duration, various radiological parameters, complication rate, and Scoliosis Research Society-30 score.ResultsThere were no significant between-group differences with respect to age, sex, etiology, flexibility of the main thoracic curve, number of fused segments and screws, and follow-up duration. Further, there was no significant difference in terms of preoperative, postoperative, and final follow-up findings of the radiographic data. However, the ARPIDF group had longer operation and hospitalization times and greater blood loss. In the ARPIDF group, 4 patient developed complications (infection, intraoperative neuromonitoring changes, transient dyspnea); none of these events occurred in the MSDR group.ConclusionThe use of MSDR helped achieve greater scoliosis correction with a shorter operation time, lower blood loss, and lower complication rate than the use of ARPIDF. MSDR facilitates safer and easier correction of severe scoliosis without increasing surgical risk.

Prospective Assessment of a Protocol Using Neuromonitoring, Early Limb Reperfusion, and Selective Temporary Aneurysm Sac Perfusion to Prevent Spinal Cord Injury During Fenestrated-branched Endovascular Aortic Repair.

The aim of this study was to analyze the outcomes of a standardized protocol using routine CSFD, neuromonitoring, LL reperfusion, and selective TASP to prevent SCI during F-BEVAR. SCI is to be the most devastating complication for the patient, family, and surgeon, with impact on patient's quality of life and long-term prognosis. An optimal standardized protocol may be used to improve outcomes. Patients enrolled in a prospective, nonrandomized single-center study between 2013 and 2018. A SCI prevention protocol was used for TAAAS or complex abdominal aneurysms with ≥5-cm supraceliac coverage including CSFD, neuromonitoring, LL reperfusion, and selective TASP. Endpoints included mortality and rates of SCI. SCI prevention protocol was used in 170 of 232 patients (73%) treated by F-BEVAR. Ninety-one patients (55%) had changes in neuromonitoring, which improved with maneuvers in all except for 9 patients (10%) who had TASP. There was one 30-day or in-hospital mortality (0.4%). Ten patients (4%) developed SCIs including in 1% (1/79) of patients with normal neuromonitoring and 10% (9/91) of those who had decline in neuromonitoring ( P = 0.02). Permanent paraplegia occurred in 2 patients (1%). Factors associated with SCI included total operating time (odds ratio 1.5, 95% confidence interval 1.1-2.2, P = 0.02) and persistent changes in neuromonitoring requiring TASP (odds ratio 15.7, 95% confidence interval 2.9-86.2, P = 0.001). This prospective nonrandomized study using a standardized strategy to prevent SCI was associated with low incidence of the SCI during F-BEVAR. Permanent paraplegia occurred in 1%.

Intraoperative Electroencephalographic Changes During Transcarotid Artery Revascularization Are More Frequent Than Previously Reported

Up to 14% of patients undergoing carotid endarterectomy with continuous electroencephalographic (EEG) neuromonitoring require shunt placement because of EEG changes. Initial studies of transcarotid artery revascularization (TCAR) found only one patient with temporary EEG changes. We report our experience with intraoperative EEG monitoring during TCAR. We conducted a retrospective review of patients from May 2017 to January 2020 who received TCAR at two urban hospitals within an integrated health care network. Data included demographic information, patient comorbidities, symptom status, prior carotid interventions, anatomic details, contralateral disease, intraoperative vital signs and EEG changes, and postoperative major adverse events (transient ischemic attack, stroke, myocardial infarction, and death) both initially and 30 days postoperatively. Fisher exact test was used for categorical data; continuous data were analyzed with Wilcoxon rank sum. A total of 89 patients underwent TCAR during the study period, of whom 71 (79.8%) had intraoperative EEG neuromonitoring; 70.8% of patients were male. Median age was 75 years (interquartile range, 68-82.5 years). Symptomatic patients accounted for 41.6% of the cohort. Of the 71 patients who had continuous neuromonitoring, 9 had EEG changes during TCAR (12.7%); changes resolved in 7 patients with pressure augmentation (2), low-flow toggle (2), and unclamping after completion of flow reversal (3). One patient who had sustained EEG changes had a new postoperative neurologic deficit. Median carotid stenosis percentage on preoperative computed tomography angiography was lower for patients with EEG changes than for those without (67% vs 80%; P = .009). Neither symptomatic carotid stenosis nor 30-day events were associated with EEG changes during TCAR (P = .49 and P = .57, respectively). Overall, there were three postoperative strokes, two postoperative deaths, and one myocardial infarction for a 30-day stroke/death/myocardial infarction rate of 7.9%. Changes in continuous EEG neuromonitoring were more frequent in our study than previously reported. Less severe carotid stenosis may be associated with a higher incidence of EEG changes. There are limited data on the prognostic ability of electroencephalography to detect clinically relevant changes during TCAR, and further study is warranted.

Clinical and Radiological Outcomes of Less Invasive Temporary Internal Distraction Followed by Staged Pedicle Screw Instrumentation in Adolescents with Severe Idiopathic Scoliosis at 2-Year Minimum Follow-Up

Temporary placement of an internal distraction rod is one of the surgical options in the treatment of severe scoliosis to avoid preoperative halo traction or vertebral column resection. This technique can be applied in a single session or staged. The aim of our study was to report the outcomes of less-invasive temporary internal distraction (LI-TID) in the surgical treatment of adolescents with severe idiopathic scoliosis (IS). We performed a single-center, retrospective study of 22 adolescents (19 girls; mean age, 14.8 ± 2.0 years) with severe IS (major curve, ≥90°) who had undergone LI-TID, followed by staged pedicle screw instrumentation, with a minimum of 2 years of follow-up available. The demographic data, radiographic outcomes, pulmonary function test results, perioperative data, revised 22-item Scoliosis Research Society Outcomes questionnaire results, complications, and neuromonitoring data were collected. The average major curve was 120° (range, 90°-160°) preoperatively and 59° (range, 29°-69°) at the final follow-up examination. Thoracic kyphosis (T5-T12) had improved from an average of 80° preoperatively to 33° postoperatively (range, 22°-69°), and the spinal height (T1-S1) had increased from 332 mm (range, 198-432 mm) preoperatively to 405 mm (range, 258-495 mm) at the final follow-up visit. Of the 22 patients, 5 (22.7%) had experienced an intraoperative neuromonitoring change without postoperative neurologic deficits, and 2 had developed superior mesenteric artery syndrome, with resolution after conservative treatment. The mean percentage of the predicted forced vital capacity had improved from 44.5% ± 11.3% to 66.5 ± 10.8 at final follow-up (P < 0.05). The total questionnaire score had improved significantly from 2.9 ± 0.61 to 4.1 ± 0.44 (P < 0.05). The results from the present study have shown that staged LI-TID, followed by pedicle screw instrumentation, is safe and effective in adolescents with severe IS, with improvements in spinal deformity, pulmonary function, and health-related quality of life.

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.

What Neuromonitoring Changes Can Be Expected During Hip Arthroscopy in the Pediatric Population?

Background: As its indications have evolved, hip arthroscopy is now performed more frequently in pediatric patients. However, despite this increase, there is a lack of evidence in the literature about its safety in this population in regard to traction injury of the nerves of the lower extremity. Purpose: To determine neuromonitoring changes of the sciatic, femoral, and obturator nerves during hip arthroscopy in the pediatric population and determine the rate of and risk factors for clinical neurapraxia. Study Design: Case series; Level of evidence, 4. Methods: A retrospective review was performed of all pediatric patients who underwent hip arthroscopy with neuromonitoring from December 2013 to October 2018. Neuromonitoring included somatosensory evoked potentials (SSEPs) in the peroneal and posterior tibial nerves and electromyography (EMG) signal for the obturator, femoral, and peroneal and posterior tibial nerves. Traction was applied using a radiolucent traction table. We recorded total traction time, surgery time, SSEP changes >50% after traction application, and EMG activity. We also recorded whether there was a clinical neurapraxia and when nerve function returned, and analyzed surgical and patient characteristic data for risk factors for neurapraxia. Results: A total of 89 patients had hip arthroscopy (median traction time, 69 minutes). SSEP changes >50% occurred in 78% of patients in the peroneal nerve and 73% in the posterior tibial nerve. EMG activity was observed in 9% of patients in the obturator nerve, 8% in the femoral nerve, 12% in the peroneal nerve, and 8% in the posterior tibial nerve. Clinical neurapraxia was seen in 19% of patients in either the peroneal nerve or posterior tibial nerve but resolved by 2 days postoperatively. Those who sustained a neurapraxia had a 32-minute longer surgery and 6-minute longer traction time. The clinical rate of neurapraxia of the pudendal nerve was 0%. Conclusion: Neuromonitoring changes are common during hip arthroscopy and nearly 1 in 5 pediatric patients will have some decreased sensation in either the peroneal or the posterior tibial nerve that resolves within 1 to 2 days after surgery. In pediatric patients, longer surgery and traction times during hip arthroscopy are associated with a higher rate of neurapraxia than that reported for adults.

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.

140. Rapid reversal of surgical steps minimizes spinal cord injury in a porcine model

BACKGROUND CONTEXT Spinal cord injuries (SCI) are one of the most devastating in spine surgery. Intraop neuromonitoring changes can occur as a secondary characteristic of spinal cord compression and decrease in spinal cord blood flow (SCBF). Laser Doppler flowmetry has been well validated for measuring SCBF. PURPOSE To determine if critical, measurable changes occur before spinal cord injury occurs. STUDY DESIGN/SETTING Porcine model. PATIENT SAMPLE Seventeen pigs. OUTCOME MEASURES Spinal cord blood flow, MEP, MAP, neurological injury, spinal canal volume. METHODS After prone positioning and induction, multilevel laminectomies are performed in the midthoracic region. LDF electrodes were placed on the exposed dura in multiple areas to measure real-time SCBF. Spinal cord injury was induced by incremental balloon inflation in the epidural space. After MEP loss (SCI), interventions were carried out: raising the systolic BP, expanding the intravascular volume with colloids, and IV lidocaine. After interventions, wake up test is performed and CT scan was done to measure the thoracic spinal canal volume. Two groups based on intervention timing. Group A: medical interventions before balloon deflation; Group B: balloon deflated first. RESULTS Seventeenpigs were studied, 14 of which survived and completed the experiment. Recordable SCBF changes from baseline were seen 3–32 minutes before MEP loss. For this reason, we considered three minutes to be the critical time before SCI. However, the 20% threshold interval was often reached before the 3-minute mark. Three minutes before MEP loss, change in SCBF was −24.9% and balloon pressure was 9 psi. Balloon volume was 0.63 cc. The spinal canal compromise 3 minutes before MEP signals loss was 69.3%, while SCBF three minutes before MEP loss was 71. This was a 24.85% change from baseline SCBF. In Group A, no pigs moved. In Group B, 9/10 were found to be moving their hind legs. CONCLUSIONS Compression SCI is the end of a cascade involving increasing pressure, decreasing volume and hypoperfusion. Rapid relief of compression leads to MEP return and function. SCBF monitoring can detect ischemia preinjury, giving surgeons an opportunity for early intervention. 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.

Neuromonitoring Changes During Hip Arthroscopy in the Pediatric Population

Objectives:The objectives of this study were to determine the prevalence, pattern, and predisposing factors for sciatic, femoral, obturator, and pudendal nerve injury during hip arthroscopy in the pediatric population.Methods:We retrospectively reviewed charts of all pediatric patients who underwent hip arthroscopy with neuromonitoring from 2013 until May 2018. Neuromonitoring included when traction was applied and removed, and somatosensory evoked potentials (SSEP) in the peroneal and posterior tibial nerves and electromyography (EMG) signal for the obturator, femoral, and peroneal and posterior tibial branch of the sciatic nerves. Each report was reviewed for total traction time, EMG changes, SSEP changes more than 50% after traction application, and the time for SSEPs to return to baseline. Demographic data and postoperative notes were reviewed for any signs of clinical nerve injury and if/when recovery occurred. We determined the rate of SSEP and EMG changes, time from traction onset to SSEP and EMG changes, time after traction released until SSEP returns to baseline, and rate of neuropraxia and any potential risk factors.Results:We identified 78 patients who underwent hip arthroscopy (16±2 years of age; 54 females). Reasons for hip arthroscopy included femoral acetabular impingement (37%), hip dysplasia with labral tear (27%), slipped capital femoral epiphysis (23%), labral tear (5%), snapping hip (3%), diagnostic scope (3%), Perthes with labral tear (1%), and trauma (1%). Average traction time was 64±30 min. SSEPs decreases of less than 50% occurred in 76% of patients in the peroneal nerve, and 69% of patients in the posterior tibial nerve. In the contralateral limb, there was a 50% drop in SSEPs in the peroneal nerve in 13% of patients and in the posterior tibial nerve in 8% of patients. For the peroneal nerve, this drop in signal occurred 23±11 min after traction was applied and returned intraoperatively at a rate of 74% 29±23 min after traction removal. For the posterior tibial nerve, this drop in signal occurred 22±12 min after traction was applied and returned intraoperatively at a rate of 83% 24±15 min. after traction removal. EMG activity was observed after traction application in 10% of patients in the obturator nerve at 36±34 min., 9% of patients in the femoral nerve at 22 ± 15 min., 14% of patients in the peroneal nerve at 19±27 min, and 5% of patients in the posterior tibial nerve at 42±42 min. The rate of pudendal nerve neuropraxia was 0%. The rate of clinical neuropraxia postoperatively was 18%. Those who sustained a neuropraxia had on average a 54 min. longer surgery (p=0.005) and a trend towards a 14 min. longer traction time (p=0.096). Diagnosis had no statistical effect on the rate of clinical diagnosis.Conclusion:Hip arthroscopy is increasingly utilized to treat several unique diagnoses in the pediatric population. As such, it is important to understand the potential risks of treating different diagnosis in this population. The important findings of this study are that neuromonitoring changes occur in more than 70% of patients and 18% will have some decreased sensation in either their peroneal nerve or posterior tibial nerve that resolves within 1-2 days after surgery. There is also a low risk of neuropraxia if there are no neuromonitoring changes during surgery. Diagnosis (Hip dysplasia/SCFE/FAI) did not change incidence of neuropraxia. Longer surgery and traction time appear to be the only risk factors for neuropraxia in hip arthroscopy in pediatric patients.

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.

WHAT NEUROMONITORING CHANGES CAN BE EXPECTED DURING HIP ARTHROSCOPY IN THE PEDIATRIC POPULATION?

WHAT NEUROMONITORING CHANGES CAN BE EXPECTED DURING HIP ARTHROSCOPY IN THE PEDIATRIC POPULATION?