Practice Trends in the Utilization of Intraoperative Neurophysiological Monitoring in Pediatric Neurosurgery as a Function of Complication Rate, and Patient-, Surgeon-, and Procedure-Related Factors

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.

Quality and patient safety research in pediatric neurosurgery: a review

BACKGROUND

In 2001, the National Academy of Medicine, formerly known as the Institute of Medicine (IOM), published their seminal work, Crossing the Quality Chasm: A New Health System for the 21st Century. In this work, the authors called for improved safety, effectiveness, patient-centeredness, timeliness, efficiency, and equity in the United States' healthcare system. Two decades after the publication of this work, healthcare costs continue to rise, but outcomes lag other nations. The objective of this narrative review is to describe research efforts in pediatric neurosurgery with respect to the six quality aims proposed by the IOM, and highlight additional research opportunities.

METHODS

PubMed, Google Scholar, and EBSCOhost were queried to identify studies in pediatric neurosurgery that have addressed the aims proposed by the IOM. Studies were summarized and synthesized to develop a set of research opportunities to advance quality of care.

RESULTS

Twenty-three studies were reviewed which focused on the six quality aims proposed by the IOM. Out of these studies, five research opportunities emerged: (1) To examine performance of tools of care, (2) To understand processes surrounding care delivery, (3) To conduct cost-effectiveness analyses for a broader range of neurosurgical conditions, (4) To identify barriers driving healthcare disparities, and (5) To understand patients' and caregivers' experiences receiving care, and subsequently develop tools and programs to address their needs and preferences.

CONCLUSION

There is a growing body of literature examining quality in pediatric neurosurgical care across all aims proposed by the IOM. However, there remains important gaps in the literature that, if addressed, will advance the quality of pediatric neurosurgical care delivery.

Intraoperative neurophysiological monitoring in Latin America: A bibliometric analysis

PURPOSE

Intraoperative Neurophysiological Monitoring (IOMM) has been used worldwide in the attempt to reduce postsurgical neurological deficits, however, most of the publications are from developed countries. There is a global bibliometric analysis of IOMN in spinal surgery, however, the contribution of Latin America (LA) is not mentioned. The aim of this study is to describe scientific productivity, patterns of publications, and thematic trends of IONM in LA.

METHODS

Data was collected using Scopus database, by searching scientific articles with LA affiliation, using 18 keywords. We excluded duplicates, not original articles, reviews, surveys, and articles not related to humans. Articles were analyzed and classified as follows: year of publication, language of the original document, journals metrics, country, IONM modality, etiology, location of surgery, medical specialties, and outcome. Descriptive statistics were used.

RESULTS

We obtained 8,699 scientific articles of which 41 scientific articles from 7 LA countries were selected. Mexico has the highest number of publications. In most countries, supratentorial location showed the highest frequency. Somatosensory evoked potentials and electrocorticography were the most performed modalities. Neurosurgery was the most involved specialty of our 41 scientific articles, and 95.1% of these publications concluded that IONM is useful to guide surgical procedures.

CONCLUSIONS

Mexico and Brazil have led IONM publications in LA. The lower reference in publications of visual evoked potentials and brainstem auditory evoked potentials IONM modalities, could be considered in the future to boost tailored research in LA.

Coordination of Intraoperative Neurophysiologic Monitoring Technologist and Surgery Schedules

Resource coordination in surgical scheduling remains challenging in health care delivery systems. This is especially the case in highly-specialized settings such as coordinating Intraoperative Neurophysiologic Monitoring (IONM) resources. Inefficient coordination yields higher costs, limited access to care, and creates constraints to surgical quality and outcomes. To maximize utilization of IONM resources, optimization-based algorithms are proposed to effectively schedule IONM surgical cases and technologists and evaluate staffing needs. Data with 10 days of case volumes, their surgery durations, and technologist staffing was used to demonstrate method effectiveness. An iterative optimization-based model that determines both optimal surgery and technologist start time (operational scenario 4) was built in an Excel spreadsheet along with Excel's Solver settings. It was compared with current practice (operational scenario 1) and optimization solution on only surgery start time (operational scenario 2) or technologist start time (operational scenario 3). Comparisons are made with respect to technologist overtime and under-utilization time. The results conclude that scenario 4 significantly reduces overtime by 74% and under-utilization time by 86% as well as technologist needs by 10%. For practices that do not have flexibility to alter surgeon preference on surgery start time or IONM technologist staffing levels, both scenarios 2 and 3 also result in substantial reductions in technologist overtime and under-utilization. Moreover, IONM technologist staffing options are discussed to accommodate technologist preferences and set constraints for surgical case scheduling. All optimization-based approaches presented in this paper are able to improve utilization of IONM resources and ultimately improve the coordination and efficiency of highly-specialized resources.

Intraoperative neurophysiology in intramedullary spinal cord tumor surgery

Intramedullary spinal cord tumor (ISCT) surgery is challenged by a significant risk of neurological injury. Indeed, while most ISCT patients arrive to surgery in good neurological condition due to early diagnosis, many experience some degree of postoperative sensorimotor deficit. Thus, intraoperative neuromonitoring (IONM) is invaluable for providing functional information that helps neurosurgeons tailor the surgical strategy to maximize resection while minimizing morbidity. Somatosensory evoked potential (SEP), muscle motor evoked potential (mMEP), and D-wave monitoring are routinely used to continuously assess the functional integrity of the long pathways within the spinal cord. More recently, mapping techniques have been introduced to identify the dorsal columns and the corticospinal tracts. Intraoperative SEP decline is not a sufficient reason to abandon surgery, since SEPs are very sensitive to anesthesia and surgical maneuvers. Yet, a severe proprioceptive deficit may adversely impact daily life, and the value of SEPs should be reconsidered. While mMEPs are good predictors of short-term motor outcome, the D-wave is the strongest predictor of long-term motor outcome, and its preservation during surgery is essential. Mapping techniques are promising but still need validation in large cohorts of patients to determine their impact on clinical outcome. The therapeutic rather than merely diagnostic value of IONM in spine surgery is still debated, but there is emerging evidence that IONM provides an essential adjunct in ISCT surgery.

Intraoperative neurophysiology in pediatric supratentorial surgery: experience with 57 cases

PURPOSE

Utilization of intraoperative neurophysiology (ION) to map and assess various functions during supratentorial brain tumor and epilepsy surgery is well documented and commonplace in the adult setting. The applicability has yet to be established in the pediatric age group.

METHODS

All pediatric supratentorial surgery utilizing ION of the motor system, completed over a period of 10 years, was analyzed retrospectively for the following variables: preoperative and postoperative motor deficits, extent of resection, sensory-motor mappability and monitorability, location of lesion, patient age, and monitoring alarms. Intraoperative findings were correlated with antecedent symptomatology as well as short- and long-term postoperative clinical outcome. The monitoring impact on surgical course was evaluated on a per-case basis.

RESULTS

Data were analyzed for 57 patients (ages 3-207 months (93 ± 58)). Deep lesions (in proximity to the pyramidal fibers) constituted 15.7% of the total group, superficial lesions 47.4%, lesions with both deep and superficial components 31.5%, and ventricular 5.2%. Mapping of the motor cortex was significantly more successful using the short-train technique than Penfield's technique (84% vs. 25% of trials, respectively), particularly in younger children. The youngest age at which motor mapping was successfully achieved was 3 vs. 93 months for each method, respectively. Preoperative motor strength was not associated with monitorability. Direct cortial motor evoked potential (dcMEP) was more sensitive than transcranial (tcMEP) in predicting postoperative motor decline. dcMEP decline was not associated with tumor grade or extent of resection (EOR); however, it was associated with lesion location and more prone to decline in deep locations. ION actively affected surgical decisions in several aspects, such as altering the corticectomy location and alarming due to a MEP decline.

CONCLUSION

ION is applicable in the pediatric population with certain limitations, depending mainly on age. When successful, ION has a positive impact on surgical decision-making, ultimately providing an added element of safety for these patients.

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.

Intraoperative neurophysiology monitoring in scoliosis surgery in children

Objective

Intraoperative neurophysiology monitoring (INM) is thought to reduce the risk of postoperative neurological deficits in children undergoing scoliosis and spine deformity surgery. INM is being used increasingly despite conflicting opinions, varied results, non-standard alarm criteria and concern regarding cost effectiveness. In this paper we present our experience with INM in scoliosis and spine deformation surgery in children, propose alert criteria and preferred anaesthetics in clinical practice.

Methods

We retrospectively analysed our experience with INM in 56 children who had 61 scoliosis and spine deformity surgeries.

Results

INM was successfully undertaken with transcranial electrical motor evoked potentials (TcMEP) and somatosensory evoked potentials. There were no injuries due to INM. Four children had 5 alerts during 4 surgeries. A postoperative deficit was seen in one child only. No new postoperative deficits were seen in any child who did not have an alert during INM. Total intravenous anaesthesia was better for INM compared to inhalational anaesthetics.

Conclusions

INM is useful in scoliosis surgery; it is likely to mitigate the risk of new deficits following surgery. We recommend alert criteria for TcMEPs that include multiple facets - amplitude, stimulus paradigm, morphology. We recommend propofol and remifentanil, in preference to sevoflurane and remifentanil for anaesthesia during INM.

Significance

Our study adds to the literature supporting the role of INM in scoliosis surgery in children. We provide guidelines for alarm criteria in clinical practice and recommend the use of total intravenous anaesthesia as the preferred anaesthetic option.

Effect of Intra- and Extraoperative Factors on the Efficacy of Intraoperative Neuromonitoring During Cervical Spine Surgery

INTRODUCTION

The purpose of the present study was to examine the effect of various extra- and intraoperative factors on the ability of neuromonitoring to predict neurological complications.

METHODS

We reviewed the data from 592 patients who had undergone cervical spine surgery with neuromonitoring at Assuta Medical Center from 2006 to 2013. We compared the somatosensory evoked potentials, transcranial electric motor evoked potentials, and electromyographic signals collected throughout surgery with the patient surgical outcome measures, demographic data, pre-existing pathological features found on neurological examination, and radiographic findings. Descriptive and inferential analyses were used to estimate the relative explanatory power contributed by these factors.

RESULTS

We included 468 patients in the present study. Neuromonitoring changes occurred in 100 patients, and the appropriate clinical intervention was undertaken in all 100, with recovery of the signals in 69. A transient neuromonitoring change was not associated with a poor outcome (only 8 of 69 patients). However, a permanent neuromonitoring change was associated with a new neurological deficit (13 of 31 patients) Changes occurring during positioning or decompression were associated with better clinical outcomes than were changes occurring during the rest of the procedure. Extraoperative factors were not associated with an increased risk of neuromonitoring changes during surgery or poorer surgical outcomes.

CONCLUSIONS

Permanent neuromonitoring changes predicted for new neurological deficits. However, transient changes were not associated with a new deficit. Neuromonitoring changes occurring during positioning and decompression had better clinical outcomes compared with those occurring during the rest of the procedure.

Demographic Trends in the Use of Intraoperative Neuromonitoring for Scoliosis Surgery in the United States

Background

Intraoperative neuromonitoring (ION), such as motor-evoked potential (MEP), somatosensory evoked potentials (SSEP), and electromyography (EMG), is used to detect impending neurological injuries during spinal surgery. To date, little is known about the trends in the use of ION for scoliosis surgery in the United States.

Methods

A retrospective review was performed using the PearlDiver Database to identify patients that had scoliosis surgery with and without ION from years 2005 to 2011. Demographic information (such as age, gender, region within the United States) and clinical information (such as type of ION and rates of neurological injury) were assessed.

Results

There were 3618 patients who had scoliosis surgery during the study period. Intraoperative neuromonitoring was used in 1361 (37.6%) of these cases. The number of cases in which ION was used increased from 27% in 2005 to 46.9% in 2011 (P < .0001). Multimodal ION was used more commonly than unimodal ION (64.6% versus 35.4%). The most commonly used modality was combined SSEP and EMG, while the least used modality was MEP only. Neurological injuries occurred in 1.8 and 2.0% of patients that had surgery with and without ION, respectively (P = .561). Intraoperative neuromonitoring was used most commonly in patients <65 years of age and in the Northeastern part of the United States (age P = .006, region P < .0001).

Conclusions

The use of ION for scoliosis surgery gradually increased annually from 2005 to 2011. Age and regional differences were noted with neuromonitoring being most commonly used for scoliosis surgery in nonelderly patients and in the Northeastern part of the United States. No differences were noted in the risk of neurological injury in patients that had surgery with and without ION. Although the findings from this study may seem to suggest that ION may not influence the risk of neurologic injury, this result must be interpreted with caution as inherently riskier surgeries may utilize ION more, leading to an actual reduction in injuries more dramatic than observed in this study.

Demographic Trends in the Use of Intraoperative Neuromonitoring for Scoliosis Surgery in the United States

Background

Intraoperative neuromonitoring (ION) such as motor-evoked potential (MEP), somatosensory evoked potentials (SSEP) and electromyography (EMG) are used to detect impending neurological injuries during spinal surgery. To date, little is known on the trends in the use of ION for scoliosis surgery in the United States.

Methods

A retrospective review was performed using the PearlDiver Database to identify patients that had scoliosis surgery with and without ION from years 2005 to 2011. Demographic information (such as age, gender, region within the United States) and clinical information (such as type of ION and rates of neurological injury) were assessed.

Results

There were 3618 patients who had scoliosis surgery during the study period. ION was used in 1361 (37.6%) of these cases. The number of cases in which ION was used increased from 27% in 2005 to 46.9% in 2011 (p < 0.0001). Multimodal ION was used more commonly than unimodal ION (64.6% vs. 35.4%). The most commonly used modality was combined SSEP and EMG while the least used modality was MEP only. Neurological injuries occurred in 1.8% and 2.0% of patients that had surgery with and without ION, respectively (p = 0.561). ION was used most commonly in patients < 65 years of age and in the Northeastern part of the United States (age; p = 0.006, region; p < 0.0001).

Conclusions

The use of ION for scoliosis surgery gradually increased annually from 2005 to 2011. Age and regional differences were noted with neuromonitoring being most commonly used for scoliosis surgery in non-elderly patients and in the Northeastern part of the United States. No differences were noted in the risk of neurological injury in patients that had surgery with and without ION. Although the findings from this study may seem to suggest that ION may not influence the risk of neurologic injury, this result must be interpreted with caution as inherently riskier surgeries may utilize ION more, leading to an actual reduction in injuries more dramatic than observed in this study.

Quantitative analysis of motor evoked potentials in the neonatal lamb

Evoking motor potentials are an objective assessment method for neuromotor function, yet this was to our knowledge never done in neonatal lambs. There is neither a method for standardized quantification of motor evoked potentials (MEPs). We first aimed to evaluate the feasibility of MEP recording in neonatal lambs and test its validity. Second we aimed to develop an algorithm for its quantification and test its reliability since manual input is required. We recorded myogenic MEPs after transcranial motor cortex stimulation in 6 lambs aged 1–2 days. MEPs were also measured in one lamb undergoing Neuro-Muscular Blockade (NMB) and another undergoing lumbar spinal cord (SC) transection, both serving as controls. We computed 5 parameters using a custom-made algorithm: motor threshold, latency, area-under-the-curve, peak-to-peak amplitude and duration. Intra- and inter-observer reliability was analyzed. MEPs could be easily recorded, disappearing after NMB and SC transection. The algorithm allowed for analysis, hence physiologic readings of the parameters in all 4 limbs of all lambs were obtained. Our method was shown to have high intra- and inter-observer ( ≥70%) reliability for latency, area-under-the-curve and peak-to-peak amplitude. These results suggest that standardized MEP recording and analysis in neonatal lambs is feasible, and can reliably assess neuromotor function.

Subcortical Mapping Using an Electrified Cavitron UltraSonic Aspirator in Pediatric Supratentorial Surgery

BACKGROUND

Intraoperative electrophysiology is increasingly used for various lesion resections, both in adult and pediatric brain surgery. Subcortical mapping is often used in adult surgery when lesions lie in proximity to the corticospinal tract (CST). We describe a novel technique of continuous subcortical mapping using an electrified Cavitron UltraSonic Aspirator (CUSA) in children with supratentorial lesions.

METHODS

We evaluated the method of subcortical mapping using a CUSA as a stimulation probe. Included in this study were children (<18 years of age) with supratentorial lesions in proximity to the CST in which the CUSA stimulator was applied. Data were collected retrospectively.

RESULTS

Eleven children were included. Lesions were located in the thalamus (3), basal-ganglia (2), lateral ventricle (1), and convexity (5). Lesions included low-grade gliomas (6), arteriovenous malformation (1), cavernoma (1), cortical dysplasia (1), ependymoma grade II (1), and high-grade glioma (1). Seven patients had positive mapping responses to CUSA-based stimulation at various stimulation intensities. These responses led to a more limited resection in 5 cases. There were no complications related to the mapping technique.

CONCLUSION

Continuous CUSA-based subcortical stimulation is a feasible mapping technique for assessing proximity to the CST during resection of supratentorial lesions in children. Future studies should be performed to better correlate the current threshold for eliciting a motor response with the distance from the CST, as well as the effect of age on this technique.

Dermal Sinus Tract of the Thoracic Spine Presenting with Intramedullary Abscess and Cranial Nerve Deficits

Congenital dermal sinus tract of the spine is an unusual developmental defect which represents a failure of the surface ectoderm and dermal elements to separate from the neuroectoderm. A 15-month-old female presented with high fever, severe right hemiparesis, difficulty breathing and cranial nerve deficits. Magnetic resonance imaging (MRI) of the spine revealed a congenital dermal sinus tract at the Th6 level, an intramedullary collection extending up to the brainstem and a probable intramedullary cystic lesion. The child was operated acutely with ligation of the sinus tract, drainage of the abscess and partial removal of the intramedullary lesion. Due to abscess recurrence, she was reoperated with complete excision of the dermal sinus tract, abscess redrainage and subtotal excision of the dermoid cyst (retaining a part of its capsule). Pus culture isolated Corynebacterium species and Peptococcus species and histology of the lesion showed a dermoid cyst. Postoperatively, after an initial neurologic deterioration, she progressively improved. An MRI scan at 15 months neither showed recurrence of the collection nor regrowth of the lesion. Spinal dermal sinus tracts that remain unnoticed or untreated can result in serious complications and should be operated as soon as possible to prevent undesirable sequelae.

Intraoperative neuromonitoring in single-level spinal procedures: a retrospective propensity score-matched analysis in a national longitudinal database

STUDY DESIGN

Retrospective propensity score-matched analysis on a national database (MarketScan) between 2006 and 2010.

OBJECTIVE

To compare rates of neurological deficits after elective single-level spinal procedures with and without intraoperative neuromonitoring, as well as associated payment differences and geographic variance.

SUMMARY OF BACKGROUND DATA

Intraoperative neurophysiologic monitoring is a technique that may contribute to avoiding permanent neurological injury during some spine surgery procedures. However, it is unclear whether all patients undergoing spine surgery benefit from neuromonitoring.

METHODS

An identified 85,640 patients underwent single-level spinal procedures including anterior cervical discectomy and fusion (ACDF), lumbar fusion, lumbar laminectomy, or lumbar discectomy. Neuromonitoring was identified with appropriate Current Procedural Terminology (CPT) codes. Cohorts were balanced on baseline comorbidities and procedure characteristics using propensity score matching. Trauma and spinal tumors cases were excluded.

RESULTS

Patients (12.66%) received neuromonitoring intraoperatively. Lumbar laminectomies had reduced 30-day neurological complication rate with neuromonitoring (0.0% vs. 1.18%, P=0.002). Neuromonitoring did not correlate with reduced intraoperative neurological complications in ACDFs (0.09% vs. 0.13%), lumbar fusions (0.32% vs. 0.58%), or lumbar discectomy (1.24% vs. 0.91%). With the addition of neuromonitoring, payments for ACDFs increased 16.24% ($3842), lumbar fusions 7.84% ($3540), lumbar laminectomies 24.33% ($3704), and lumbar discectomies 22.54% ($2859). Significant geographic variation was evident. Some states had no recorded single-level spinal cases with concurrent neuromonitoring. Rates for ACDFs and lumbar fusions, laminectomies, and discectomies ranged as high as 61%, 58%, 22%, and 21%, respectively.

CONCLUSION

With intraoperative neurological monitoring in single-level procedures, neurological complications were decreased only among lumbar laminectomies. No difference was observed in ACDFs, lumbar fusions, or lumbar discectomies. There was a significant increase in total payments associated with the index procedure and hospitalization. We demonstrate significant geographic variation in neuromonitoring.

LEVEL OF EVIDENCE

3.