Efficacy of Intraoperative Neurophysiologic Monitoring for Pediatric Cervical Spine Surgery

Pediatric Intraoperative Neurophysiological Monitoring and Long-Term Outcomes in a Developing Country

PURPOSE

Pediatric intraoperative neurophysiological monitoring (IONM) has been shown to be effective in preventing and reversing postoperative neurological deficits in developed countries. There are currently no published studies from developing countries that describe neurophysiological findings and postoperative outcomes. Our study aims to address these gaps in children undergoing neurosurgical procedures in a single center.

METHODS

We conducted a retrospective study of case series of children who underwent IONM (2014-2020) in the State of Mexico, Mexico. Sociodemographic characteristics, IONM modalities, changes during procedures, and short-term and long-term postoperative results were recorded. Descriptive statistics were used.

RESULTS

We included 35 patients (≤18 years of age), 57% (20/35) boys. A relative increase of up to 5 times in the use of IONM is observed from 2014 (5.7%) to 2020 (25.7%) in our center. The most frequent preoperative pathologies were located at the infratentorial cranium (40%), followed by the spine and spinal cord (37.1%). The IONM modalities were as follows: free-running EMG 94.3%, transcranial electrical stimulation motor-evoked potentials 91.4%, somatosensory-evoked potentials 85.7%, triggered EMG 28.6%, EEG 25.7%, and visual-evoked potentials 5.7%. Only in 8.3%, we did not obtain sufficient evoked potential baseline signals. At 24 hours postoperatively true negatives were 100%. Long-term follow-up was completed in 22/35 (63%) at 3 months, 12/35 (34.2%) at 6 months, and 5/35 (14.3%) at 12 months with progressive motor and sensory improvement.

CONCLUSIONS

Pediatric multimodal IONM in neurosurgeries from a single center in a developing country is mainly used in pathologies of the posterior fossa, spine, and spinal cord, with true negatives in 100% of those monitored, preventing and avoiding postoperative sequelae.

Preprocedural Electrophysiological Monitoring in Craniofacial Surgery for a Patient with Chiari Malformation

Head and neck positioning is a key element of craniofacial reconstructive surgery and can become challenging when intervention necessitates broad exposure of the calvarium. We present a case of craniosynostosis secondary to Apert's syndrome requiring anterior and posterior cranial vault access during surgical correction. A modified sphinx position was used that required significant neck extension. The patient had concurrent Chiari I malformation with brain stem compression so intraoperative neuromonitoring (IONM) was used to ensure that there were no negative effects on the neural elements with positioning. This highlights benefits of IONM in a setting not typically associated with its use.

Relevance of intraoperative motor evoked potentials and D-wave monitoring for the resection of intramedullary spinal cord tumors in children

The purpose of this study was to evaluate the reliability of motor evoked potentials (MEP), somatosensory evoked potentials (SSEP), and D-wave monitoring as predictors of postoperative neurological deficits in pediatric patients undergoing resection of intramedullary spinal cord tumors (IMSCTs). Additionally, we aimed to determine whether alerts in the intraoperative neurophysiological monitoring (IONM) influenced the extent of resection (EOR). A retrospective analysis of the pediatric patients who underwent resection of IMSCT between March 2010 and April 2021 with an IONM guidance was performed. IONM alerts were recorded and correlated with patients' clinical status at discharge. Twenty three pediatric patients were included. MEP and SSEP were successfully elicited in all patients, while D-wave monitoring was feasible for 14 of them (60.9%). Significant IONM alerts occurred in 6 individuals (26.1%) with monitorable MEP and SSEP and 2 patients with monitorable D-waves (14.3%). The sensitivity, specificity, positive predictive value, and negative predictive value accounted for 100%, 81.8%, 20%, 100% for MEP, 100%, 92.3%, 50%, 100% for D-wave, and 50%, 81%, 20%, 94.44% for SSEP, respectively. Both MEP (p < 0.001) and D-wave monitoring (p < 0.001) accurately predicted postoperative motor deficits, while SSEP failed to provide significant accuracy regarding sensory deficits (p = 0.491). Gross-total tumor resection was performed in 29.4% of patients without IONM alerts and 33.3% of patients with IONM alerts, indicating that IONM alerts did not limit the EOR (p = 0.0857). MEP and D-wave monitoring can be perceived as reliable IONM modalities in pediatric IMSCTs surgery. Caution is needed with the implementation of SSEP to guide surgical decisions.

Surgical Causes of Significant Intraoperative Neuromonitoring Signal Changes in Three-Column Spinal Surgery

Study Design

Retrospective case series.

Purpose

To evaluate the risks and causes of neurologic complications in three-column spinal surgery by analyzing intraoperative neurophysiological monitoring (IONM) data.

Overview of Literature

Three-column spinal surgery, which may be required to correct complex spinal deformities or resection of spinal tumors, is known to carry a high risk of neurologic complications. However, few studies reported a specific surgical procedure related to a significant IONM signal change during surgery.

Methods

Multimodality IONM data, including somatosensory-evoked potentials (SSEP) and motor-evoked potentials (MEP), were reviewed in 64 patients who underwent three-column spinal surgery from 2011 to 2015. Surgical procedures included posterior vertebral column resection, pedicle subtraction osteotomy, total en bloc spondylectomy, piecemeal spondylectomy, and corpectomy with laminectomy (n=27) in three cervical, 34 thoracic, and 31 lumbar procedures.

Results

Significant IONM signal changes occurred in 11 of 64 (17.1%) patients. SSEP and MEP were changed in 11 patients. Postoperative neurologic deterioration occurred in 54.5% (6 of 11) of the patients, and two of them were permanent. There was no postoperative neurologic deterioration in patients without significant signal change. Suspected causes of IONM data changes are as follows: adhesion/tethering, translation, contusion, and perfusion.

Conclusions

Based on the results of this study, to enhance neurologic safety in three-column spinal surgery, surgeons should pay attention to protect the spinal cord from mechanical insult, especially when the spinal column was totally destabilized during surgery, and not to compromise perfusion to the spinal cord in close cooperation with a neurologist and anesthesiologist.

Narcotrend-guided intraoperative care of a Trisomy 21 paediatric patient who underwent occipitocervical fusion

A 9-year-old female with Trisomy 21 with complex craniovertebral instability causing severe cervicomedullary compression underwent occipitocervical fusion. This paper will discuss the anaesthetic management and highlight the use of the Narcotrend monitor not only as a depth of consciousness monitor but more importantly as a tool to detect surgery-induced cerebral hypoperfusion by monitoring the right and left cerebral hemispheres independently and simultaneously.

Perioperative acute neurological deficits in instrumented pediatric cervical spine fusions

OBJECTIVE

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.

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 neurological deficits were defined as the deterioration of preexisting neurological function or the appearance of new neurological symptoms.

RESULTS

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).

CONCLUSIONS

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.

Feasibility of intraoperative monitoring of motor evoked potentials obtained through transcranial electrical stimulation in infants younger than 3 months

OBJECTIVE

This study aimed to investigate the feasibility and safety of intraoperative motor evoked potential (MEP) monitoring in infants less than 3 months of age.

METHODS

The authors investigated 25 cases in which infants younger than 3 months (mean age 72.8 days, range 39-87) underwent neurosurgery between 2014 and 2017. Myogenic MEPs were obtained through transcranial electrical stimulation. In all cases, surgery was performed under total intravenous anesthesia, maintained with remifentanil and propofol.

RESULTS

MEPs were documented in 24 infants, the sole exception being 1 infant who was lethargic and had 4-limb weakness before surgery. The mean stimulation intensity maintained during monitoring was 596 ± 154 V (range 290-900 V). In 19 of 24 infants MEP signals remained at ≥ 50% of the baseline amplitude throughout the operation. Among 5 cases with a decrease in intraoperative MEP amplitude, the MEP signal was recovered in one during surgery, and in the other case a neurological examination could not be performed after surgery. In the other 3 cases, 2 infants had relevant postoperative weakness and the other did not show postoperative neurological deficits. Postoperative weakness was not observed in any of the 20 infants who had no deterioration (n = 19) or only temporary deterioration (n = 1) in MEP signal during surgery.

CONCLUSIONS

Transcranial electrical MEPs could be implemented during neurosurgery in infants between 1 and 3 months of age. Intraoperative MEP monitoring may be a safe adjunct for neurosurgical procedures in these very young patients.

Neurophysiological monitoring during neurosurgery: anesthetic considerations based on outcome evidence

PURPOSE OF REVIEW

This article reviews the recent outcome studies that investigated intraoperative neurophysiological monitoring (IONM) during spine, neurovascular and brain tumor surgery.

RECENT FINDINGS

Several recent studies have focused on identifying which types of neurosurgical procedures might benefit most from IONM use. Despite conflicting literature regarding its efficacy in improving neurological outcomes, many experts have advocated for the use of IONM in neurosurgery. Several themes have emerged from the recent literature: the entire perioperative team must always work together to ensure adequate communication and intervention; systems and checklists, in which each member of the perioperative team has a clearly defined role, can be useful in the event of a sudden intraoperative changes in electrophysiological signals; regardless of the IONM modality used, any sudden change in electrophysiological signal should prompt an immediate and appropriate intervention; a multimodal IONM approach is often, but not always, advantageous over a single IONM approach.

SUMMARY

For neurosurgical procedures that can be complicated by neural injury, the use of IONM should be considered according to specific patient and surgical factors. Future studies should focus on improving IONM technology and optimizing sensitivity and specificity for detecting any impending neural damage.

The Recognition, Incidence, and Management of Spinal Cord Monitoring Alerts in Pediatric Cervical Spine Surgery

BACKGROUND

Perioperative spinal cord injury and postoperative neurological deficits are the major complications in spinal surgery. Monitoring of spinal cord function is of crucial importance. Somatosensory evoked potentials and transcranial electric motor-evoked potentials are now widely used in cervical spine surgery. Although much has been written on spinal cord monitoring in adult spinal surgery, very little has been published on the incidence and management of monitoring of cervical spine surgery in the pediatric population. The goal of this research was to review the recognition, incidence, and management of spinal cord monitoring in pediatric patients undergoing cervical spine surgery over the course of twenty years in a single institution. We postulate spinal cord monitoring alerts in pediatric cervical spine surgery are underreported.

METHODS

An IRB-approved retrospective single institution review of pediatric cervical spine cases from 1997 to 2017 was performed. Both the surgeon's dictated operative note and the neuromonitoring team's dictated note were reviewed for each case, and both were cross referenced and correlated with one another to ensure no alerts were missed. All monitoring changes were assumed to be significant and reported. The incidence of alerts, type of changes, and corrective maneuvers were noted. New postoperative neurological injuries were recorded.

RESULTS

From 1997 to 2017 fifty-three patients underwent a total of 69 procedures involving the cervical spine. Fourteen procedures (20%) were not monitored, whereas 55 procedures were 80%. There were 12 procedures (21.8%) complicated by neuromonitoring alerts.

CONCLUSIONS

The number of cases complicated by alerts doubles that previously reported, and it is important to note there were no new permanent neurological deficits recorded over the study period. Corrective strategies were implemented once the operating surgeon was notified of the neuromonitoring alert. Aborting the case was then considered if corrective strategies failed to restore baseline neurophysiology.

LEVEL OF EVIDENCE

Level IV.

Outcomes from 18 years of cervical spine surgery in MPS IVA: a single centre's experience

PURPOSE

This study examines the long-term outcomes of paediatric Morquio (MPS IVA) patients undergoing cervical spine surgery and evaluates the factors that impacting this.

METHODS

A retrospective review was performed on all MPS IVA patients undergoing cervical spine surgery, since the introduction of standardised neuroradiological screening. The impact of preoperative neurological status, growth, genotype and radiological status on outcome is assessed, whilst long-term surgical, radiological and neurological outcomes are documented.

RESULTS

Twenty-six of the eighty-two MPS IVA patients (31%) reviewed underwent cervical spine surgery at a median age of 6.1 years (range, 1.45 to 15.24). Preoperatively, cord signal change was seen in 11 patients with 5 being myelopathic; however, 6 clinically manifesting patients had no overt cord signal change. Postoperatively, none of the 14 preoperatively clinically asymptomatic patients followed long term progressed neurologically during a median follow-up of 77.5 months (range = 18-161). Of the ten preoperatively clinically symptomatic patients who were followed up for the same duration, seven continued to deteriorate, two initially improved and one remained stable. Radiological follow-up performed for a median duration of 7 years (range = 0.5-16) has shown a degree of stenosis at the level immediately caudal to the termination of the graft in 76% of patients, though only one has become clinically symptomatic and required revision.

CONCLUSIONS

Once clinically elicitable neurological signs become evident in patients with MPS IVA, they tend to progress despite surgical intervention. Referring clinicians should also not be falsely reassured by the lack of T2 spinal cord signal change but should consider surgical intervention in the face of new clinical symptomology or radiological signs of progressive canal stenosis or instability.

[Intraoperative neuromonitoring in cervical deformity surgery]

Correction of cervical deformity is associated with a considerable risk of neurological deterioration. The use of intraoperative neuromonitoring (IOM) can, however, significantly increase patient safety. Nonetheless, data on the effectiveness of IOM during reconstructive cervical surgery are very limited. Since the surgical maneuvers in reconstructive cervical surgery represent the same dangers to the spinal cord as in scoliosis correction, the same influence of IOM on the clinical outcome may be assumed. IOM has been shown to decrease the rate of neurological complications in scoliosis surgery. Herein, we discuss the current evidence for the efficacy of IOM during reconstructive cervical surgery as well as during scoliosis surgery.