Intraoperative Monitoring Events Research Articles

Postoperative dysesthesia after PVCR without anterior support applied in Yang's type A severe spinal kyphoscoliosis.

The incidence and characteristics of postoperative dysesthesia (POD) have not been reported for posterior vertebral column resection (PVCR) in the treatment of severe spinal kyphoscoliosis. The objective of the study is to investigate the incidence and characteristics of POD in PVCR without anterior support applied in Yang's type A severe spinal kyphoscoliosis. From August 2010 to December 2019, 167 patients diagnosed with Yang's type A severe spinal kyphoscoliosis who underwent PVCR without anterior support applied were retrospectively reviewed. All the patients were monitored using five modes of intraoperative multimodal neurophysiological monitoring. Neuromonitoring data, radiographic parameters, and neurological complications were reviewed and analyzed. The incidence and characteristics of POD were further summarized. POD was defined as dysesthetic pain or burning dysesthesia which could be caused by spinal cord kinking or dorsal root ganglion (DRG) injury but with no motor deficits. PVCR without anterior support was successfully conducted in all 167 patients. Intraoperative monitoring events occurred in five patients. One out of these five patients showed postoperative spinal cord injury (Frankel level C) but completely recovered within 9 months postoperation (Frankel level E). The number of levels and osteotomy space for vertebra resection were 1.28 and 3.6 cm, respectively. POD was confirmed in three patients (3/167, 1.8%), characterized as kyphosis with the apex vertebrae in T12 with the kyphotic Cobb angles of 100°, 115°, and 122°, respectively. The osteotomy space of vertebra resection in these three patients were 3.9, 3.8, and 4.2 cm, respectively. After the treatment by drug administration, they reported pain relief for 12-36 days. The pain gradually moved to the distal end of a proper DRG innervated region near the end. In this study, the incidence rate of POD in Yang's type A severe spinal kyphoscoliosis patients who underwent PVCR without anterior support applied was 1.8% (3/167). Evoked potential monitoring could not detect the occurrence of POD. POD in Yang's type A severe spinal kyphoscoliosis after PVCR could be ascribed to spinal cord kinking and DRG injury.

One-stage Spine-shortening Osteotomy Treated Severe Spinal Deformity Associated With Spinal Cord Malformations.

Retrospective case series. To evaluate the safety and efficacy of spine-shortening using 1-stage 3-column osteotomy for a severe rigid spinal deformity with a spinal cord malformation (SCM). One-stage spine-shortening osteotomy has been suggested for the treatment of a tethered spinal cord. However, the safety and efficacy of 1-stage spine-shortening osteotomy for the treatment of a severe spinal deformity with an SCM is not known. The records of 32 patients with a severe spinal deformity and SCM treated with spine-shortening using 3-column osteotomy from January 2010 to December 2016 were analyzed retrospectively. Intraoperative neurophysiological monitoring was used in all cases. Imaging parameters and neurological complications were analyzed to evaluate clinical safety and efficacy. Spine-shortening using a 3-column osteotomy was conducted successfully in all 32 patients. The mean main coronal curve and maximum kyphotic angle were corrected from 119.8 and 119.1 degrees to 58.6 and 53.9 degrees, respectively, with the corrective rate of 51.4% and 54.3%. The mean correction loss of the major coronal curve and maximum kyphosis was 2.3 and 2.6 degrees, respectively, at a mean follow-up of 73.6 months. Intraoperative monitoring events occurred in 9 patients; of these 9 patients, 3 suffered transient SC injury, and all recovered within 1 year without suffering permanent paralysis. Spine-shortening using a 3-column osteotomy seems to be safe and efficacious for treating a severe spinal deformity with an SCM. A deep understanding of the method and intensive intraoperative neuromonitoring improved the safety of this challenging and complex surgical procedure.

Predicting the Extent of Resection of Motor-Eloquent Gliomas Based on TMS-Guided Fiber Tracking.

Background: Surgical planning with nTMS-based tractography is proven to increase safety during surgery. A preoperative risk stratification model has been published based on the M1 infiltration, RMT ratio, and tumor to corticospinal tract distance (TTD). The correlation of TTD with corticospinal tract to resection cavity distance (TRD) and outcome is needed to further evaluate the validity of the model. Aim of the study: To use the postop MRI-derived resection cavity to measure how closely the resection cavity approximated the preoperatively calculated corticospinal tract (CST) and how this correlates with the risk model and the outcome. Methods: We included 183 patients who underwent nTMS-based DTI and surgical resection for presumed motor-eloquent gliomas. TTD, TRD, and motor outcome were recorded and tested for correlations. The intraoperative monitoring documentation was available for a subgroup of 48 patients, whose responses were correlated to TTD and TRD. Results: As expected, TTD and TRD showed a good correlation (Spearman’s ρ = 0.67, p < 0.001). Both the TTD and the TRD correlated significantly with the motor outcome at three months (Kendall’s Tau-b 0.24 for TTD, 0.31 for TRD, p < 0.001). Interestingly, the TTD and TRD correlated only slightly with residual tumor volume, and only after correction for outliers related to termination of resection due to intraoperative monitoring events or the proximity of other eloquent structures (TTD ρ = 0.32, p < 0.001; TRD ρ = 0.19, p = 0.01). This reflects the fact that intraoperative monitoring (IOM) phenomena do not always correlate with preoperative structural analysis, and that additional factors influence the intraoperative decision to abort resection, such as the adjacency of other vulnerable structures. The TTD was also significantly correlated with variations in motor evoked potential (MEP) responses (no/reversible decrease vs. irreversible decrease; p = 0.03). Conclusions: The TTD approximates the TRD well, confirming the best predictive parameter and giving strength to the nTMS-based risk stratification model. Our analysis of TRD supports the use of the nTMS-based TTD measurement to estimate the resection preoperatively, also confirming the 8 mm cutoff. Nevertheless, the TRD proved to have a slightly stronger correlation with the outcome as the surgeon’s experience, anatomofunctional knowledge, and MEP observations influence the expected EOR.

Multimodal Intraoperative Spinal Cord Monitoring during Spinal Deformity Surgery: Efficacy, Diagnostic Characteristics, and Algorithm Development

Objective: This study aims to present the diagnostic characteristics of multimodal intraoperative monitoring (IOM) in spinal deformity surgery and to define and categorise the neuromonitoring events, as well as propose an algorithm of action. Materials and Methods: We reviewed 1,155 consecutive patients (807 female, 348 male) who underwent deformity correction using standardised perioperative care, cortical/cervical somatosensory evoked potentials (SSEPs), and upper/lower limb transcranial electrical motor evoked potential (MEPs) by a single surgeon. The mean age at surgery was 13.8 years (range 10–23.3). We categorised IOM events as true, transient true, and false positive or negative. Diagnostic performance criteria were calculated. Results: The most common diagnosis was adolescent idiopathic scoliosis in 717 (62%) patients. We identified 3 true positive monitoring events occurring in 2 patients (0.17%), 8 transient true positive (0.69%), and 8 transient false positive events (0.69%). There were no false negative events and no patient had postoperative neurological complications. The multimodal IOM technique had a sensitivity of 100%, specificity of 99.3%, positive predictive value of 55.6%, and negative predictive value of 100%. Sensitivity was 100% for MEPs and multimodal monitoring compared to 20% for cortical or cervical SSEPs. The frequency of true or transient true positive events was higher (p = 0.07) in Scheuermann’s kyphosis (3/91 patients, 3.3%) compared to adolescent idiopathic scoliosis (6/717 patients, 0.84%). Conclusion: Multimodal IOM is highly sensitive and specific for spinal cord injury. This technique is reliable for the assessment of the condition of the spinal cord during major deformity surgery. We propose an algorithm of intraoperative action to allow close cooperation between the surgical, anaesthetic, and neurophysiology teams and to prevent neurological deficits.

Predictive Value of Spinal Cord Function Classification and Sagittal Deformity Angular Ratio for Neurologic Risk Stratification in Patients with Severe and Stiff Kyphoscoliosis

Three-column osteotomies were developed to treat severe spinal deformities but result in high neurologic complications and require further risk stratification. The present study investigated whether the combination of spinal cord function classification (SCFC) and deformity angular ratio (DAR) could further stratify the neurologic risks in the surgical correction of severe and stiff kyphoscoliosis. The patients with kyphoscoliosis who had undergone posterior 3-column osteotomies at the spinal cord level were reviewed. Using our SCFC system, the preoperative neurologic function (type A, B, or C) was classified. The sagittal DAR (S-DAR), coronal, and total DARs were calculated. Intraoperative monitoring events and new neurologic deficits (NNDs) postoperatively were documented and analyzed using the SCFC and DAR or both combined. The NND rates increased significantly from type A to C (P= 0.000) and increased exponentially with an increase in S-DAR in types B and C but not type A. They also increased exponentially with aggravation of the SCFC in the medium and high but not low S-DAR group. All NNDs had recovered at 3 months for type A and most had recovered at 6 months for type B or C. The NNDs in type A SCFC usually experienced better recovery even with high S-DARs. Type B SCFC with an S-DAR >20° and type C SCFC with any S-DAR resulted in significantly greater intra- and postoperative neurologic risks. The combination of SCFC and S-DAR can further stratify the intra- and postoperative neurologic risks with these procedures.

The Safety and Efficiency of PVCR without Anterior Support Applied in Treatment of Yang Type A Severe Thoracic Kyphoscoliosis.

To assess the clinical and radiographic outcomes of posterior vertebral column resection (PVCR) without anterior support in treatment of Yang type A severe rigid thoracic kyphoscoliosis. The records of 27 Yang type A severe thoracic kyphoscoliosis patients treated with PVCR without anterior support from January 2010 to September 2013 were analyzed retrospectively. Intraoperative multimodal neurophysiological monitoring was conducted in all patients. The 6 modes were somatosensory evoked potential, motor evoked potential, descending neurogenic evoked potential, spinal cord evoked potential, and electromyography (both triggered and free run). Radiographic parameters and complications were used to evaluate the clinical outcomes. PVCR without anterior support was conducted successfully in all 27 patients. Intraoperative monitoring events occurred in 3 patients (3/27); of these, 1 patient (1/27) showed postoperative spinal cord injury, but completely recovered within 9 months after the operation (Frankel level E). The number and osteotomy space of vertebrae resection were mean 1.33 levels and 3.7 cm, respectively. All cases achieved good coronal and sagittal curve correction. No implant related complications occurred until the latest follow-up. The average follow-up was 40.1 months (range, 24-59 months). In this study, we found that posterior vertebral column resection (PVCR) without any anterior support with a mean 3.7 cm shortening of the spinal column is safe, if close and unyielding contact of end plates can be obtained. A comprehensive understanding of the technique and intensive intraoperative neuromonitoring is mandatory to perform these challenging and complex spine deformity correction procedures safely.

The risk factors of neurological monitoring events in severe thoracic vertebral column resection cases

Objective To evaluate the effect of multimodality intraoperative neurophysiological monitoring (IONM) for severe thoracic posterior vertebral column resection (PVCR) surgery, and detail the risk factors of intraoperative monitoring events at various surgery procedures. Methods Monitoring data at various surgery procedures in 82 severe thoracic posterior vertebral column resection cases treated in our center between January 2010 and March 2015 were reviewed. This series of cases including 37 female and 45 male, the initial age averaged 22.6±9.6 years (range 8-66 years). All patients were followed up for minimum 1 year (average 40.7±18.2 months, range 12-74 months). The etiologies of spinal deformity were idiopathic in 36 cases, congenital in 20 patients, tuberculosis in 3 Patients, neurofibromatosis in 9 patients, and neuromuscular in 13 cases. The function of spinal cord and nerve root were assessed by SEP+MEP+ DNEP and tEMG+sEMG combined monitoring during operation, respectively. The monitoring outcomes and the risk factors of cord monitoring events were recorded and analyzed, and then prevention measures were suggested according to our clinical practice and literature review. Results In these cohort cases, combined monitoring of SEP+MEP+DNEP+tEMG+sEMG was successfully achieved in all 82 cases. On average, the major coronal curve was corrected from a preoperative 122.3°±27.6° to a postoperative 55.1°±21.5°, with a correction rate of 55.4%. The sagittal kyphosis was corrected from a preoperative 123.4°±27.8° to a postoperative 53.8°±19.7°, with a correction rate of 56.2%. The average resection vertebra was 1.33±0.6 levels with 11 meshes and 18 cages being planted into 29 patients. The average intra-operative blood loss and surgery time were 2911±1358 ml and 505±105 mins. There were 39 monitoring changes occurred in 27 cases out of 82 (32.9%). Results indicated that neurological monitoring events were more likely to occur in patients with larger scoliosis and kyphosis, longer closure distance of osteotomy, more Halo gravity traction, more screw insertion and higher PVCR segments. The reasons of monitoring changes included screw malposition (6/39), hypotension (2/39), osteotomy maneuver (5/39), cord concussion (4/39), bony compression (7/39), subluxation (4/39), styptic gauze compression (3/39), cord kniking (4/39), and over correction (4/39). After timely detection and intervention during operation, 11 of 82 cases presented new post-operative neural deficit, including 1 incomplete paralysis, 8 transient cord deficit and 2 nerve root injury. Conclusion IONM is effective to predict the spinal cord deficit at different surgery stages. Our report showed PVCR and PVCR site closure had a relatively high neurological risk, and operative manipulation was the main reason of monitoring events. Key words: Thoracic vertebrae; Spinal curvatures; Osteotomy; Evoked potentials, somatosensory; Evoked potentials, motor; Electromyography

Multimodal intraoperative monitoring during intramedullary spinal cord tumor surgery.

The aim of this work is to evaluate the utility of multimodal intraoperative monitoring (IOM) during intramedullary spinal cord tumor (IMSCT) surgery in our institution, and to investigate which IOM events are likely to be encountered during critical surgical phases. Twenty-five patients who underwent IMSCT surgery with IOM were included in this study. Our multimodal IOM assessment included SSEP, mMEP, and fEMG monitoring. Positive predictive value (PPV), negative predictive value (NPV), sensitivity, and specificity were assessed 24 h and 1 month after surgery. The IOM events during three main surgical phases were also investigated. For mMEP assessment, two warning criteria (>50 % decrease in mMEP amplitude and all-or-none mMEP amplitude presence) were employed. Long-term outcome prediction was better when the all-or-none criterion was applied than when the >50 % amplitude decrease criterion was applied. Based on the all-or-none criterion, the PPV, NPV, sensitivity, and specificity were 60, 100, 100, and 91 %. Frequent IOM events were observed during the three major main surgical phases. Seven (29 %) patients showed SSEP events during opening of the spinal cord. During tumor removal, 21 of 25 patients (84 %) had IOM events, and 13 of 18 (72 %) of the fEMG events occurred prior to the mMEP events. Based on the association of fEMG events with upcoming mMEP events during tumor removal, we recommend inclusion of fEMG monitoring in IOM. Multimodal IOM provides useful electrophysiological information during IMSCT surgery, especially during the main surgical phases.

Implementation of Intraoperative Neurophysiological Monitoring during Endovascular Procedures in the Central Nervous System

Background and Objective: Intraoperative monitoring (IOM) has been used in different surgical disciplines since the 1980s. Nonetheless, regular routine use of IOM in interventional neuroradiology units has only been reported in a few centers. The aim of this study is to report our experience, 1 year after deciding to implement standardized IOM during endovascular treatment of vascular abnormalities of the central nervous system. Methods: Basic recordings included somatosensory-evoked potentials (SEPs) and motor-evoked potentials (MEPs). Corticobulbar motor-evoked potentials and flash-visual-evoked potentials were also recorded depending on the topography of the lesion. Intra-arterial provocative tests (PTs) with amobarbital and lidocaine were also performed. All patients except 1 were under total intravenous anesthesia. Clinical outcome was assessed prospectively and correlated with IOM events. Results: Twelve patients and 15 procedures were monitored during the inclusion period. Significant IOM events were detected during 3 of the 15 procedures (20%). We observed temporary MEP changes in 2 cases which resolved after interruption of the embolization or application of corrective measures, leaving no postoperative neurological deficits. In 1 case, persistent SEP and MEP deterioration was detected secondary to a frontal hematoma, resulting in mild sensory-motor deficit in the right upper extremity after the procedure. Overall, 12 PTs (4 spinal cord and 8 brain abnormalities) were performed using lidocaine and sodium amytal injections. One positive result occurred after the injection of lidocaine. No false negatives were detected. Conclusions: IOM may provide continuous real-time data about the functional status of eloquent areas and pathways of the central nervous system in patients under general anesthesia. It therefore allows us to detect early neurological damage in time to perform specific actions that may prevent irreversible neurological deficits.

Characterization of Significant Neurophysiologic Intraoperative Monitoring Events in Severe Spinal Deformity Surgery

Characterization of Significant Neurophysiologic Intraoperative Monitoring Events in Severe Spinal Deformity Surgery