A socioeconomic analysis of intraoperative neurophysiological monitoring during spine surgery: national use, regional variation, and patient outcomes

Intraoperative Neurophysiological Monitoring for Intradural Extramedullary Spinal Tumours

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Intraoperative neurophysiological monitoring (IONM) is widely used in spinal neurosurgery, particularly for intramedullary tumours. However, its validity in intradural extramedullary (IDEM) spinal tumours is less clearly defined, this being the focus of this study.

METHODS

We compared outcomes for patients that underwent resection of IDEM tumours with and without IONM between 2010 and 2020. Primary outcomes were postoperative American Spinal Injury Association (ASIA) scores. Other factors assessed were use of intraoperative ultrasound, drain placement, postoperative complications, postoperative Eastern Cooperative Oncology Group (ECOG) score, extent of resection, length of hospital stay, discharge location and recurrence.

RESULTS

163 patients were included, 71 patients in the IONM group and 92 in the non-IONM group. No significant differences were noted in baseline demographics. For preoperative ASIA D patients, 44.0% remained ASIA D and 49.9% improved to ASIA E in the IONM group, compared to 39.7% and 30.2% respectively in the non-IONM group. For preoperative ASIA E patients, 50.3% remained ASIA E and 44.0% deteriorated to ASIA D in the IONM group, compared to 30.2% and 39.7% respectively in the non-IONM group (all other patients deteriorated further). Length of inpatient stay was significantly shorter in the IONM group (P = .043). There were no significant differences in extent of resection, postoperative complications, discharge location or tumour recurrence.

CONCLUSIONS

Research focusing on the use of IONM in IDEM tumour surgery remains scarce. Our study supports the use of IONM during surgical excision of IDEM tumours.

Accuracy of Intraoperative Neuromonitoring in the Diagnosis of Intraoperative Neurological Decline in the Setting of Spinal Surgery-A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVES

In an effort to prevent intraoperative neurological injury during spine surgery, the use of intraoperative neurophysiological monitoring (IONM) has increased significantly in recent years. Using IONM, spinal cord function can be evaluated intraoperatively by recording signals from specific nerve roots, motor tracts, and sensory tracts. We performed a systematic review and meta-analysis of diagnostic test accuracy (DTA) studies to evaluate the efficacy of IONM among patients undergoing spine surgery for any indication.

METHODS

The current systematic review and meta-analysis was performed using the Preferred Reporting Items for a Systematic Review and Meta-analysis statement for Diagnostic Test Accuracy Studies (PRISMA-DTA) and was registered on PROSPERO. A comprehensive search was performed using MEDLINE, EMBASE and SCOPUS for all studies assessing the diagnostic accuracy of neuromonitoring, including somatosensory evoked potential (SSEP), motor evoked potential (MEP) and electromyography (EMG), either on their own or in combination (multimodal). Studies were included if they reported raw numbers for True Positives (TP), False Negatives (FN), False Positives (FP) and True Negative (TN) either in a 2 × 2 contingency table or in text, and if they used postoperative neurologic exam as a reference standard. Pooled sensitivity and specificity were calculated to evaluate the overall efficacy of each modality type using a bivariate model adapted by Reitsma et al, for all spine surgeries and for individual disease groups and regions of spine. The risk of bias (ROB) of included studies was assessed using the quality assessment tool for diagnostic accuracy studies (QUADAS-2).

RESULTS

A total of 163 studies were included; 52 of these studies with 16,310 patients reported data for SSEP, 68 studies with 71,144 patients reported data for MEP, 16 studies with 7888 patients reported data for EMG and 69 studies with 17,968 patients reported data for multimodal monitoring. The overall sensitivity, specificity, DOR and AUC for SSEP were 71.4% (95% CI 54.8-83.7), 97.1% (95% CI 95.3-98.3), 41.9 (95% CI 24.1-73.1) and .899, respectively; for MEP, these were 90.2% (95% CI 86.2-93.1), 96% (95% CI 94.3-97.2), 103.25 (95% CI 69.98-152.34) and .927; for EMG, these were 48.3% (95% CI 31.4-65.6), 92.9% (95% CI 84.4-96.9), 11.2 (95% CI 4.84-25.97) and .773; for multimodal, these were found to be 83.5% (95% CI 81-85.7), 93.8% (95% CI 90.6-95.9), 60 (95% CI 35.6-101.3) and .895, respectively. Using the QUADAS-2 ROB analysis, of the 52 studies reporting on SSEP, 13 (25%) were high-risk, 10 (19.2%) had some concerns and 29 (55.8%) were low-risk; for MEP, 8 (11.7%) were high-risk, 21 had some concerns and 39 (57.3%) were low-risk; for EMG, 4 (25%) were high-risk, 3 (18.75%) had some concerns and 9 (56.25%) were low-risk; for multimodal, 14 (20.3%) were high-risk, 13 (18.8%) had some concerns and 42 (60.7%) were low-risk.

CONCLUSIONS

These results indicate that all neuromonitoring modalities have diagnostic utility in successfully detecting impending or incident intraoperative neurologic injuries among patients undergoing spine surgery for any condition, although it is clear that the accuracy of each modality differs.PROSPERO Registration Number: CRD42023384158.

Traumatic spinal injury-related hospitalizations in the United States, 2016-2019: a retrospective study

BACKGROUND

Traumatic spinal injury (TSI) is associated with significant fatality and social burden; however, the epidemiology and treatment of patients with TSI in the US remain unclear.

MATERIALS AND METHODS

An adult population was selected from the National Inpatient Sample database from 2016 to 2019. TSI incidence was calculated and TSI-related hospitalizations were divided into operative and nonoperative groups according to the treatments received. TSIs were classified as fracture, dislocation, internal organ injury, nerve root injury, or sprain injuries based on their nature. The annual percentage change (APC) was calculated to identify trends. In-hospital deaths were utilized to evaluate the prognosis of different TSIs.

RESULTS

Overall, 95 047 adult patients were hospitalized with TSI in the US from 2016 to 2019, with an incidence rate of 48.4 per 100 000 persons in 2019 (95% CI: 46.2-50.6). The total incidence increased with an APC of 1.5% (95% CI: 0.1-3%) from 2016 to 2019. Operative TSI treatment was more common than nonoperative (32.8 vs. 3.8; 95% CI: 32.3-33.2 vs. 3.6-4%). The number of operations increased from 37 555 (95% CI: 34 674-40 436) to 40 460 (95% CI: 37 372-43 548); however, the operative rate only increased for internal organ injury (i.e. spinal cord injury [SCI])-related hospitalizations (APC, 3.6%; 95% CI: 2.8-4.4%). In-hospital mortality was highest among SCI-related hospitalizations, recorded at 3.9% (95% CI: 2.9-5%) and 28% (95% CI: 17.9-38.2%) in the operative and nonoperative groups, respectively.

CONCLUSIONS

The estimated incidence of TSI in US adults increased from 2016 to 2019. The number of operations increased; however, the proportion of operations performed on TSI-related hospitalizations did not significantly change. In 2019, SCI was the highest associated mortality TSI, regardless of operative or nonoperative treatment.

Postoperative ileus risk after posterior thoracolumbar fusion performed with total intravenous anesthesia versus inhaled anesthesia

OBJECTIVE

There has been an increase in the use of total intravenous anesthesia (TIVA) for intraoperative neuromonitoring during thoracolumbar posterior spinal fusion (PSF). Although prior studies have identified risk factors for postoperative ileus (PI) after PSF, to the authors' knowledge, PI rates in patients receiving inhaled anesthetic versus TIVA have not been evaluated. In this study the authors analyzed whether TIVA is associated with greater risk of PI in PSF patients.

METHODS

In this retrospective single-institution cohort study, all patients undergoing PSF at the authors' tertiary academic institution from May 2014 to December 2020 were included. Patients undergoing anterior/lateral approaches or who had concurrent abdominal procedures unrelated to ileus in the same admission were excluded. PI was defined using radiographic and/or clinical diagnoses (postoperative radiographs, abdominal CT, and/or ICD-9 or -10 codes) and was confirmed via chart review. The use of TIVA or inhaled anesthetic was captured from the anesthesia record; patients were excluded if they were missing anesthesia technique data. Postoperative occurrence of PI was compared between patients who had TIVA or inhaled anesthetics while controlling for collected demographic, clinical, and surgical variables.

RESULTS

Of the 2819 patients meeting inclusion criteria, 283 (10.0%) had PI (mean ± SD age 59.3 ± 15.8 years; 155 [54.8%] male). The mean patient length of stay was 7.7 ± 5.0 days, which was significantly longer than that of patients without PI (4.9 ± 3.9 days, p < 0.001). Patients with PI had more levels fused (46% of PI patients with ≥ 5 levels fused vs 25% of non-PI patients, p < 0.001) and longer operations (6.0 ± 2.2 vs 5.4 ± 1.9 hours, p < 0.001). TIVA patients were more likely than inhalation-only patients to experience PI, but this finding did not reach significance on univariate analysis (11.0% PI rate vs 8.9%, p = 0.06). After propensity matching 125 non-PI patients and 50 PI patients by age, sex, operative time, and number of levels fused, there was a significant difference in intraoperative opiate dosing between TIVA and inhalational patients (275.7 ± 187.5 intravenous morphine milligram equivalents vs 120.9 ± 155.5, p < 0.001). On multivariate analysis of PI outcome, TIVA was an independently significant predictor (OR 1.45, p = 0.02), as was anesthesia time (OR per hour increase: 1.09, p = 0.03) and ≥ 8 levels fused (OR 1.86, p = 0.01).

CONCLUSIONS

In a large cohort of PSF patients, TIVA was associated with a higher rate of PI compared with inhaled anesthetic. This effect is likely due to higher intraoperative opiate use in these patients.

Current Trends in Intraoperative Spinal Cord Monitoring: A Survey Analysis among Japanese Expert Spine Surgeons

Introduction

Although intraoperative spinal neuromonitoring (IONM) is recommended for spine surgeries, there are no guidelines regarding its use in Japan, and its usage is mainly based on the surgeon's preferences. Therefore, this study aimed to provide an overview of the current trends in IONM usage in Japan.

Methods

In this web-based survey, expert spine surgeons belonging to the Japanese Society for Spine Surgery and Related Research were asked to respond to a questionnaire regarding IONM management. The questionnaire covered various aspects of IONM usage, including the preferred modality, operation of IONM, details regarding muscle-evoked potential after electrical stimulation of the brain (Br(E)-MsEP), and need for consistent use of IONM in major spine surgeries.

Results

Responses were received from 134 of 186 expert spine surgeons (response rate, 72%). Of these, 124 respondents used IONM routinely. Medical staff rarely performed IONM without a medical doctor. Br(E)-MsEP was predominantly used for IONM. One-third of the respondents reported complications, such as bite injuries caused by Br(E)-MsEP. Interestingly, two-thirds of the respondents did not plan responses to alarm points. Intramedullary spinal cord tumor, scoliosis (idiopathic, congenital, or neuromuscular in pediatric), and thoracic ossification of the posterior longitudinal ligament were representative diseases that require IONM.

Conclusions

IONM has become an essential tool in Japan, and Br(E)-MsEP is a predominant modality for IONM at present. Although we investigated spine surgeries for which consistent use of IONM is supported, a cost-benefit analysis may be required.

Monitoring scoliosis and other spinal deformity surgeries

Surgery to correct a spinal deformity incurs a risk of injury to the spinal cord and roots. Injuries include postoperative paraplegia. Surgery for cervical myelopathy also incurs risk for postoperative motor deficits, as well as nerve injury most commonly at the C5 root. Risks can be mitigated by monitoring the nervous system during surgery. Ideally, monitoring detects an impending injury in time to intervene and correct the impairment before it becomes permanent. Monitoring includes several modalities of testing. Somatosensory evoked potentials measure axonal conduction in the spinal cord posterior columns. This can be checked almost continuously during surgery. Motor evoked potentials measure conduction along the lateral corticospinal tracts. Because motor pathway stimulation often produces a patient movement on the table, these often are tested periodically rather than continuously. Electromyography observes for spontaneous discharges accompanying injuries, and is useful to assess misplacement of pedicle screws. Literature demonstrates the usefulness of these techniques, their association with reducing motor adverse outcomes, and the relative value of the techniques. Neurophysiologic monitoring for scoliosis, kyphosis, and cervical myelopathy surgery are addressed, along with background information about those conditions.

The utility of intraoperative neuromonitoring on simple posterior lumbar fusions-analysis of the National Inpatient Sample

BACKGROUND

Several studies have demonstrated the utility of intraoperative neuromonitoring (IOM) including somatosensory evoked potentials (SSEPs), motor-evoked potentials (MEPs), and electromyography (EMG), in decreasing the risk of neurologic injury in spinal deformity procedures. However, there is limited evidence supporting the routine use of IOM in elective posterolateral lumbar fusion (PLF).

METHODS

The National Inpatient Sample (NIS) was analyzed for the years 2012-2015 to identify patients undergoing elective PLF with (n=22,404) or without (n=111,168) IOM use. Statistical analyses were conducted to assess the impact of IOM on length of stay, total charges, and development of neurologic complications. These analyses controlled for age, gender, race, income percentile, primary expected payer, number of reported comorbidities, hospital teaching status, and hospital size.

RESULTS

The overall use of IOM in elective PLFs was found to have increased from 14.6% in the year 2012 to 19.3% in 2015. The total charge in hospitalization cost for all patients who received IOM increased from $129,384.72 in 2012 to $146,427.79 in 2015. Overall, the total charge of hospitalization was 11% greater in the IOM group when compared to those patients that did not have IOM (P<0.001). IOM did not have a statistically significant impact on the likelihood of developing a neurological complication.

CONCLUSIONS

While there may conceivably be benefits to the use of this technology in complex revision fusions or pathologies, we found no meaningful benefit of its application to single-level index PLF for degenerative spine disease.

Neurologic Complications in Monitored versus Unmonitored Image-Guidance Assisted Posterior Lumbar Instrumentation

BACKGROUND

Intraoperative neurophysiologic monitoring (IOM) has been used clinically since the 1970s and is a reliable tool for detecting impending neurologic compromise. However, there are mixed data as to whether long-term neurologic outcomes are improved with its use. We investigated whether IOM used in conjunction with image guidance produces different patient outcomes than with image guidance alone.

METHODS

We reviewed 163 consecutive cases between January 2015 and December 2018 and compared patients undergoing posterior lumbar instrumentation with image guidance using and not using multimodal IOM. Monitored and unmonitored surgeries were performed by the same surgeons, ruling out variability in intersurgeon technique. Surgical and neurologic complication rates were compared between these 2 cohorts.

RESULTS

A total of 163 patients were selected (110 in the nonmonitored cohort vs. 53 in the IOM cohort). Nineteen signal changes were noted. Only 3 of the 19 patients with signal changes had associated neurologic deficits postoperatively (positive predictive value 15.7%). There were 5 neurologic deficits that were observed in the nonmonitored cohort and 8 deficits observed in the monitored cohort. Transient neurologic deficit was significantly higher in the monitored cohort per case (P < 0.0198) and per screw (P < 0.0238); however, there was no difference observed between the 2 cohorts when considering permanent neurologic morbidity per case (P < 0.441) and per screw (P < 0.459).

CONCLUSIONS

The addition of IOM to cases using image guidance does not appear to decrease long-term postoperative neurologic morbidity and may have a reduced diagnostic role given availability of intraoperative image-guidance systems.

Achieving Value in Spine Surgery: 10 Major Cost Contributors

STUDY DESIGN

Narrative Review.

OBJECTIVES

The increasing cost of healthcare overall and for spine surgery, coupled with the growing burden of spine-related disease and rising demand have necessitated a shift in practice standards with a new emphasis on value-based care. Despite multiple attempts to reconcile the discrepancy between national recommendations for appropriate use and the patterns of use employed in clinical practice, resources continue to be overused-often in the absence of any demonstrable clinical benefit. The following discussion illustrates 10 areas for further research and quality improvement.

METHODS

We present a narrative review of the literature regarding 10 features in spine surgery which are characterized by substantial disproportionate costs and minimal-if any-clear benefit. Discussion items were generated from a service-wide poll; topics mentioned with great frequency or emphasis were considered. Items are not listed in hierarchical order, nor is the list comprehensive.

RESULTS

We describe the cost and clinical data for the following 10 items: Over-referral, Over-imaging & Overdiagnosis; Advanced Imaging for Low Back Pain; Advanced imaging for C-Spine Clearance; Advanced Imaging for Other Spinal Trauma; Neuromonitoring for Cervical Spine; Neuromonitoring for Lumbar Spine/Single-Level Surgery; Bracing & Spinal Orthotics; Biologics; Robotic Assistance; Unnecessary perioperative testing.

CONCLUSIONS

In the pursuit of value in spine surgery we must define what quality is, and what costs we are willing to pay for each theoretical unit of quality. We illustrate 10 areas for future research and quality improvement initiatives, which are at present overpriced and underbeneficial.

Gender Disparity and Potential Strategies for Improvement in Neurology and Clinical Neurophysiology

Discrimination in the workplace when documented is illegal but is seen to still exist in some forms whether based on culture, race, or gender. Each of these disparities warrants further discussion and study because of their significant impacts on hiring decisions, career advancement, and compensation. In this article, the authors have focused their attention on gender disparity in the fields of neurology and clinical neurophysiology and shared the data currently available to them. At a time when the field of clinical neurophysiology has seen enormous growth, gender disparity in leadership and compensation remain. Despite the increasing number of women entering the fields of neurology and clinical neurophysiology, women remain underrepresented in national leadership positions. Many women physicians report experiencing gender discrimination despite increasing efforts by universities and medical centers to improve inclusivity and diversity. Equity and inclusivity are not the same and there is a disconnect between the increased numbers of women and their shared experiences in the workplace. Implicit bias undermines the ability of women to advance in their careers. For neurologists, data indicate that the latest gender pay gap is $56,000 (24%), increased from $37,000 in 2015, and is one of the largest pay gaps in any medical specialty. One third of the top 12 medical schools in the United States require that maternity leave be taken through disability coverage and/or sick benefits, and most family leave policies constrain benefits to the discretion of departmental leadership. The authors recommend strategies to improve gender disparity include institutional training to Identify and overcome biases, changes to professional organizations and national scientific meeting structure, transparency in academic hiring, promotion and compensation, and mentorship and sponsorship programs.

Clinical Outcomes of Intraoperative Contrast-Enhanced Ultrasound Compared with Intraoperative Neurophysiological Monitoring During Circumferential Decompression for Myelopathy Associated with Thoracic-Ossification of the Posterior Longitudinal Ligament

Background

Circumferential decompression (CD) is an essential treatment option for myelopathy associated with thoracic-ossification of the posterior longitudinal ligament (T-OPLL) when laminectomy cannot achieve sufficient ventral decompression. Although intraoperative neurophysiological monitoring (IONM) is widely used, the operation has a relatively high risk. This study is the first to describe the use of contrast-enhanced ultrasound (CEUS) to evaluate the spinal cord blood flow (SCBF) during thoracic spine surgery in humans. The objective of this study was to compare clinical outcomes between intraoperative CEUS and IONM during CD.

Material/Methods

Sixty-eight T-OPLL patients who received CD from 2007 to 2014 were reviewed. All patients underwent IONM. CEUS was used on the following 2 occasions on 18 patients to evaluate SCBF: the first measurement was performed after laminectomy and the second after ventral decompression. Outcomes were evaluated by the Hirabayashi recovery rate (HRR).

Results

The overall HRR of all patients was 56.7%. Regarding CEUS, the HRR was 20.0% in Group A (SCBF decreased) and 63.6% in Group B (SCBF increased), indicating a significantly poorer neurological outcome in Group A (P<0.01). Regarding IONM, the HRR did not significantly differ between Groups C (no meaningful change in potential), D (potential changed up to alert criteria), and E (potential improved).

Conclusions

IONM is relatively effective in detecting impending spinal cord dysfunction. Intraoperative CEUS is a safe and reliable method for assessing SCBF changes, which may be used as a supplement to IONM, thus reducing the incidence of false-negative results.

The Use of Intraoperative Neurophysiological Monitoring in Spine Surgery

STUDY DESIGN

Narrative review.

OBJECTIVE

To summarize relevant studies regarding the utilization of intraoperative neurophysiological monitoring (IONM) techniques in spine surgery implemented in recent years.

METHODS

A literature search of the Medline database was performed. Relevant studies from all evidence levels have been included. Titles, abstracts, and reference lists of key articles were included.

RESULTS

Multimodal intraoperative neurophysiological monitoring (MIONM) has the advantage of compensating for the limitations of each individual technique and seems to be effective and accurate for detecting perioperative neurological injury during spine surgery.

CONCLUSION

Although there are no prospective studies validating the efficacy of IONM, there is a growing body of evidence supporting its use during spinal surgery. However, the lack of validated protocols to manage intraoperative alerts highlights a critical knowledge gap. Future investigation should focus on developing treatment methodology, validating practice protocols, and synthesizing clinical guidelines.

Indication and technical implementation of the intraoperative neurophysiological monitoring during spine surgeries-a transnational survey in the German-speaking countries

BACKGROUND

Intraoperative neurophysiological monitoring is widely used in spine surgery (sIONM). But guidelines are lacking and its use is mainly driven by individual surgeons' preferences and medicolegal advisements. To gain an overview over the current status of sIONM implementation, we conducted a transnational survey in the German-speaking countries.

METHODS

We developed a Web interface-based survey assessing prevalence, indication, technical implementation, and general satisfaction regarding sIONM in German, Austrian, and Swiss spine centers. The electronic survey was performed between November 2017 and April 2018, including both neurosurgical and orthopedic spine centers.

RESULTS

A total of 463 German, 60 Austrian, and 52 Swiss spine centers were contacted with participation rates of 64.1% (Germany), 68.3% (Austria), and 55.8% (Switzerland). Some 75.9% participating neurosurgical spine centers and only 14.7% of the orthopedic spine centers applied sIONM. Motor- and somatosensory-evoked potentials (93.7% and 94.3%, respectively) were the most widely available modalities, followed by direct wave (D wave; 66.5%). Whereas sIONM utilization was low in spine surgeries for degenerative, traumatic, and extradural tumor diseases, it was high for scoliosis and intradural tumor surgeries. Overall, the general satisfaction within the institutional setting regarding technical skills, staff, performance, and reliability of sIONM was rated as "high" by more than three-quarters of the centers. However, shortage of skilled staff was claimed to be a negative factor by 41.1% of the centers and reimbursement was considered to be insufficient by 83.5%.

CONCLUSIONS

sIONM availability was high in neurosurgical but low in orthopedic spine centers. Main modalities were motor/somatosensory-evoked potentials and main indications were scoliosis and intradural spinal tumor surgeries. A more frequent sIONM use, however, was mainly limited by the shortage of skilled staff and restricted reimbursement.

Influence of Intraoperative Neuromonitoring on the Outcomes of Surgeries for Pediatric Scoliosis in the United States

BACKGROUND

Intraoperative neuromonitoring (IONM) is used to detect impending neurologic damage during complex spinal surgeries. Although IONM is increasingly used during pediatric scoliosis surgeries in the United States, the effect of IONM on the outcomes of such surgeries at a national level is unclear.

METHODS

Using National Inpatient Sample (NIS) from 2009 to 2012, 32,305 spinal fusions performed in children 18 years old or younger of age with scoliosis were identified using ICD-9 procedure and diagnosis codes. IONM was identified using the ICD-9 procedure code 00.94. The effects of IONM use on length of stay (LOS), discharge disposition, hospital charges, and in-hospital complications were assessed using multivariate regression analysis adjusting for patient and hospital characteristics.

RESULTS

IONM was used in 5,706 (18%) of the surgeries. IONM was associated with increased home discharge (adjusted odds ratio [AOR] = 1.25 [95% confidence interval 1.10-1.40], p = .001). There was no difference in LOS (p = .096) and hospital charges (p = .750). Neurologic complications were noted in 52 (0.9%) surgeries using IONM and 368 (1.4%) surgeries without IONM (p = .005). Although IONM use trended toward lower risk of neurologic complications in multivariate analysis, it failed to achieve statistical significance (AOR = 0.77 [0.57-1.04], p = .084).

CONCLUSIONS

Reported use of IONM in this database was significantly less compared with other databases, suggesting that IONM might be underreported in the NIS database. Nevertheless, in this database, IONM was significantly associated with increased home discharge. Hospital charges and LOS were not affected by IONM. There was a trend toward lower risk of neurologic complications with IONM use, though this finding was not statistically significant.

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.

Neurophysiological monitoring during cervical spine surgeries: Longitudinal costs and outcomes

OBJECTIVES

Well-designed longitudinal studies assessing effectiveness of intraoperative neurophysiologic monitoring (IONM) are lacking. We investigate IONM effects on cost and administrative markers for health outcomes in the year after cervical spine surgery.

METHODS

We identified single-level cervical spine surgeries in commercial claims. We constructed linear regression models estimating the effect of IONM (controlling for patient demographics, pre-operative health, services during index admission) on total spending, neurological complications, readmissions, and outpatient opiate usage in the year following index surgery.

RESULTS

IONM was associated with increased spending during index admission of $1229 (p = 0.001), but decreased spending post-discharge of $1615 (p = 0.010), for a net - $386 (p = 0.608) for the year after surgery. Shorter length of stay (0.116 days, p = 0.004) and fewer readmissions (20.5 per thousand, p = 0.036) accounted for some post-discharge savings. IONM was associated with decreased rates of nervous system complications (4/1000, p = 0.048) and post-discharge opiate use (17 prescriptions/1000, p = 0.050) in the year after index admission.

CONCLUSIONS

IONM was associated with administrative markers suggesting improved health outcomes after cervical spine surgery without greater costs for the year.

SIGNIFICANCE

This study suggests IONM may have lasting health and cost benefits.

Utilization of intraoperative neuromonitoring throughout the United States over a recent decade: an analysis of the nationwide inpatient sample

BACKGROUND

To identify temporal changes to the demographics and utilization of intraoperative neuromonitoring (IONM) throughout the United States (U.S.).

METHODS

The National Inpatient Sample (NIS) database was queried for IONM of central and peripheral nervous electrical activity (ICD-9-CM 00.94) between 2008 and 2014. The NIS database represents a 20% sample of discharges from U.S. Hospitals, weighted to provide national estimates. Demographic and economic data were obtained which included the annual number of surgeries, age, sex, insurance type, location, and frequency of routine discharge.

RESULTS

The estimated use of IONM of central and peripheral nervous electrical activity increased 296%, from 31,762 cases in 2008 to 125,835 cases in 2014. Based on payer type, privately insured patients (45.0%), rather than Medicare (36.8%) or Medicaid patients (9.2%), were more likely to undergo IONM during spinal procedures. When stratifying by median income for patient zip code, there was a substantial difference in the rates of IONM between low (19.9%) and high-income groups (78.1%). IONM was significantly more likely to be utilized at urban teaching hospitals (72.9%) rather than nonteaching hospitals (25.0%) or rural centers (2.2%).

CONCLUSIONS

Over the last decade, there has been a massive increase of 296% in utilization of IONM during spine surgery. This is likely due to its proven benefit in reducing neurologic morbidity in spinal deformity surgery, while introducing minimal additional risk. While IONM may improve patient care, it is still rather isolated to teaching hospitals and patients from higher income zip codes.

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.

Changes in transcranial electrical motor-evoked potentials during the early and reversible stage of permanent spinal cord ischemia predict spinal cord injury in a rabbit animal model

The present study examined changes in the transcranial electrical motor-evoked potentials (TceMEP) waveform to predict neurological deficits and histopathological changes during the early and reversible stage of different levels of permanent spinal cord ischemic injury in a rabbit animal model. A total of 24 New Zealand rabbits were randomly divided into four groups of 6 rabbits each. Group 1 underwent a ligation of the lumbar artery at three levels (L1-L3), group 2 underwent a ligation of the lumbar artery at four levels (L1-L4) and group 3 underwent a ligation of the lumbar artery at five levels (L1-L5). The sham group contained 6 rabbits and did not receive ligation. TceMEP was recorded within 5 min of ligation and, 2 days later, motor function was assessed and the spinal cords were removed for histological examination. Following spinal cord injury, the relationship between variations in the TceMEP waveform and motor function and pathological damage was analyzed. It was observed that the amplitude of TceMEP began to decrease within 1 min of lumbar artery ligation and that the amplitude stabilized within 5 min. These amplitude changes that occurred within 5 min of different levels of permanent spinal cord ischemic injury were positively related to changes in motor function following recovery from anesthesia and 2 days after ligation. The Pearson correlation coefficient was 0.980 and 0.923 for these two time points, respectively (P<0.001). In addition, the amplitude changes were positively related to pathological damage, with a Pearson correlation coefficient of 0.945 (P<0.001). The results of the present study suggested that amplitude changes in TceMEP are particularly sensitive to ischemia. Ischemia may be detected within 1 min and the amplitude changes begin to stabilize within 5 min following ligation of the lumbar artery. The use of intraoperative monitoring of TceMEP allows for the detection of spinal cord ischemic injury with no time delay, which may allow for protective measures to be taken to prevent the occurrence of irreversible spinal cord injury.

Utility of Intraoperative Neuromonitoring for Lumbar Pedicle Screw Placement Is Questionable: A Review of 9957 Cases

STUDY DESIGN

A retrospective database study.

OBJECTIVE

The goal of this study was to (1) evaluate the trends in the use of electromyography (EMG) for instrumented posterolateral lumbar fusions (PLFs) in the United States and (2) assess the risk of neurological injury following PLFs with and without EMG.

SUMMARY OF BACKGROUND DATA

Neurologic injuries from iatrogenic pedicle wall breaches during screw placement are known complications of PLFs. The routine use of intraoperative neuromonitoring (ION) such as EMG during PLF to improve the accuracy and safety of pedicle screw implantation remains controversial.

METHODS

A retrospective review was performed using the PearlDiver Database to identify patients who had PLF surgery with and without EMG for lumbar disorders from years 2007 to 2015. Patients undergoing concomitant interbody fusions or spinal deformity surgery were excluded. Demographic trends and risk of neurological injuries were assessed.

RESULTS

During the study period, 2007 to 2015, 9957 patients underwent PLFs. Overall, EMG was used in 2495 (25.1%) of these patients. There was a steady increase in the use of EMG from 14.9% in 2007 to 28.7% in 2009, followed by a steady decrease to 21.9% in 2015 (P < 0.0001). The risk of postoperative neurological injuries following PLFs was 1.35% (134/9957) with a risk of 1.36% (34/2495) with EMG and 1.34% (100/7462) without EMG (P = 0.932). EMG is used most commonly for PLFs in the Southern part of the United States.

CONCLUSION

In this retrospective national database review, we found that there was a steady increase in the routine use of EMG for PLFs followed by a steady decline. Regional differences were observed in the utility of EMG for PLFs. The risk of neurological complications following PLF in the absence of spinal deformity is low and the routine use of EMG for PLF may not decrease the risk.

LEVEL OF EVIDENCE

4.

Quality Programs in Neurosurgery: The Memorial Hermann/University of Texas Experience

The importance of outcome measures is steadily increasing due to the rise of "pay for performance" and the advent of population health. In 2007, a quality initiative was started due to poor performance on rankings such as the University Health Consortium (UHC) report card. Inherent to all such efforts are common challenges: how to engage the providers; how to gather and ensure the accuracy of the data; how to attribute results to individuals; how to ensure permanent improvements. After analysis, a strategy was developed that included an initial focus on 3 metrics (mortality, infection rates, and complications), leadership from practicing neurosurgeons, protocol development and adherence, and subspecialization. In addition, it was decided that the metrics would initially apply to attending physicians only, but that the entire team would need to be involved. Once the fundamental elements were established, the process could be extended to other measures and providers. To support this effort, special information system tools were developed and a support team formed. As the program matured, measured outcomes improved and more metrics were added (to a current total of 48). For example, UHC mortality ratios (observed over expected) decreased by 75%. Infection rates decreased 80%. The program now involves all trainee physicians, advanced practice providers, nurses, and other staff. This paper describes the design, implementation, and results of this effort, and provides a practical guide that may be useful to other groups undertaking similar initiatives.

Intraoperative Neuromonitoring for Anterior Cervical Spine Surgery: What Is the Evidence?

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVE

The goal of this study was to (i) assess the risk of neurological injury after anterior cervical spine surgery (ACSS) with and without intraoperative neuromonitoring (ION) and (ii) evaluate differences in the sensitivity and specificity of ION for ACSS.

SUMMARY OF BACKGROUND DATA

Although ION is used to detect impending neurological injuries in deformity surgery, it's utility in ACSS remains controversial.

METHODS

A systematic search of multiple medical reference databases was conducted for studies on ION use for ACSS. Studies that included posterior cervical surgery were excluded. Meta-analysis was performed using the random-effects model for heterogeneity. Outcome measure was postoperative neurological injury.

RESULTS

The search yielded 10 studies totaling 26,357 patients. The weighted risk of neurological injury after ACSS was 0.64% (0.23-1.25). The weighted risk of neurological injury was 0.20% (0.05-0.47) for ACDFs compared with 1.02% (0.10-2.88) for corpectomies. For ACDFs, there was no difference in the risk of neurological injury with or without ION (odds ratio, 0.726; confidence interval, CI, 0.287-1.833; P = 0.498). The pooled sensitivities and specificities of ION for ACSS are 71% (CI: 48%-87%) and 98% (CI: 92%-100%), respectively. Unimodal ION has a higher specificity than multimodal ION [unimodal: 99% (CI: 97%-100%), multimodal: 92% (CI: 81%-96%), P = 0.0218]. There was no statistically significant difference in sensitivities between unimodal and multimodal [68% vs. 88%, respectively, P = 0.949].

CONCLUSION

The risk of neurological injury after ACSS is low although procedures involving a corpectomy may carry a higher risk. For ACDFs, there is no difference in the risk of neurological injury with or without ION use. Unimodal ION has a higher specificity than multimodal ION and may minimize "subclinical" intraoperative alerts in ACSS.

LEVEL OF EVIDENCE

3.

Routine Use of Intraoperative Neuromonitoring During ACDFs for the Treatment of Spondylotic Myelopathy and Radiculopathy Is Questionable: A Review of 15,395 Cases

STUDY DESIGN

A retrospective database study.

OBJECTIVE

The goal of this study was to (1) evaluate the trends in the use of intraoperative neuromonitoring (ION) for anterior cervical discectomy and fusion (ACDF) surgery in the United States and (2) assess the incidence of neurological injuries after ACDFs with and without ION.

SUMMARY OF BACKGROUND DATA

Somatosensory-evoked potentials (SSEPs) and motor-evoked potentials (MEPs) are the commonly used ION modalities for ACDFs. Controversy exists on the routine use of ION for ACDFs and there is limited literature on national practice patterns of its use.

METHODS

A retrospective review was performed using the PearlDiver Patient Record Database to identify cases of spondylotic myelopathy and radiculopathy that underwent ACDF from 2007 to 2014. The type of ION modality used and the rates of neurological injury after surgery were assessed.

RESULTS

During the study period, 15,395 patients underwent an ACDF. Overall, ION was used in 2627 (17.1%) of these cases. There was a decrease in the use of ION for ACDFs from 22.8% in 2007 to 4.3% use in 2014 (P < 0.0001). The ION modalities used for these ACDFs were quite variable: SSEPs only (48.7%), MMEPs only (5.3%), and combined SSEPs and MMEPs (46.1%). Neurological injuries occurred in 0.23% and 0.27% of patients with and without ION, respectively (P = 0.84). Younger age was associated with a higher utility of ION (<45: 20.3%, 45-54: 19.3%, 55-64: 16.6%, 65-74: 14.3%, and >75: 13.6%, P < 0.0001). Significant regional variability was observed in the utility of ION for ACDFs across the country (West; 21.9%, Midwest; 12.9% (P < 0.0001).

CONCLUSION

There has been a significant decrease in the use of ION for ACDFs. Furthermore, there was significant age and regional variability in the use of ION for ACDFs. Use of ION does not further prevent the rate of postoperative neurological complications for ACDFs as compared with the cases without ION. The utility of routine ION for ACDFs is questionable.

LEVEL OF EVIDENCE

3.

Spinal fusion for pediatric neuromuscular scoliosis: national trends, complications, and in-hospital outcomes

OBJECTIVE The objective of this study was to determine if the recent changes in technology, surgical techniques, and surgical literature have influenced practice trends in spinal fusion surgery for pediatric neuromuscular scoliosis (NMS). In this study the authors analyzed recent trends in the surgical management of NMS and investigated the effect of various patient and surgical factors on in-hospital complications, outcomes, and costs, using the Nationwide Inpatient Sample (NIS) database. METHODS The NIS was queried from 2002 to 2011 using International Classification of Diseases, Ninth Edition, Clinical Modification codes to identify pediatric cases (age < 18 years) of spinal fusion for NMS. Several patient, surgical, and short-term outcome factors were included in the analyses. Trend analyses of these factors were conducted. Both univariate and multivariable analyses were used to determine the effect of the various patient and surgical factors on short-term outcomes. RESULTS Between 2002 and 2011, a total of 2154 NMS fusion cases were identified, and the volume of spinal fusion procedures increased 93% from 148 in 2002 to 286 in 2011 (p < 0.0001). The mean patient age was 12.8 ± 3.10 years, and 45.6% of the study population was female. The overall complication rate was 40.1% and the respiratory complication rate was 28.2%. From 2002 to 2011, upward trends (p < 0.0001) were demonstrated in Medicaid insurance status (36.5% to 52.8%), presence of ≥ 1 comorbidity (40.2% to 52.1%), and blood transfusions (25.2% to 57.3%). Utilization of posterior-only fusions (PSFs) increased from 66.2% to 90.2% (p < 0.0001) while combined anterior release/fusions and PSF (AR/PSF) decreased from 33.8% to 9.8% (< 0.0001). Intraoperative neurophysiological monitoring (IONM) underwent increasing utilization from 2009 to 2011 (15.5% to 20.3%, p < 0.0001). The use/harvest of autograft underwent a significant upward trend between 2002 and 2011 (31.3% to 59.8%, p < 0.0001). In univariate analysis, IONM use was associated with decreased complications (40.7% to 33.1%, p = 0.049) and length of stay (LOS; 9.21 to 6.70 days, p <0.0001). Inflation-adjusted mean hospital costs increased nearly 75% from 2002 to 2011 ($36,805 to $65,244, p < 0.0001). In the multivariable analysis, nonwhite race, highest quartile of median household income, greater preexisting comorbidity, long-segment fusions, and use of blood transfusions were found to increase the likelihood of complication occurrence (all p < 0.05). In further multivariable analysis, independent predictors of prolonged LOS included older age, increased preexisting comorbidity, the AR/PSF approach, and long-segment fusions (all p < 0.05). Lastly, the likelihood of increased hospital costs (at or above the 90th percentile for LOS, 14 days) was increased by older age, female sex, Medicaid insurance status, highest quartile of median household income, AR/PSF approach, long-segment fusion, and blood transfusion (all p < 0.05). In multivariable analysis, the use of autograft was associated with a lower likelihood of complication occurrence and prolonged LOS (both p < 0.05). CONCLUSIONS Increasing use of IONM and posterior-only approaches may combat the high complication rates in NMS. The trends of increasing comorbidities, blood transfusions, and total costs in spinal fusion surgery for pediatric NMS may indicate an increasingly aggressive approach to these cases.

Predictors of outcomes and hospital charges following atlantoaxial fusion

BACKGROUND CONTEXT

Atlantoaxial fusion is used to correct atlantoaxial instability that is often secondary to traumatic fractures, Down syndrome, or rheumatoid arthritis. The effect of age and comorbidities on outcomes following atlantoaxial fusion is unknown.

PURPOSE

This study aimed to better understand trends and predictors of outcomes and charges following atlantoaxial fusion and to identify confounding variables that should be included in future prospective studies.

STUDY DESIGN

A retrospective analysis of data from the Nationwide Inpatient Sample (NIS), a nationally representative, all-payer database of inpatient diagnoses and procedures in the United States.

PATIENT SAMPLE

We included all patients who underwent atlantoaxial fusion (International Classification of Disease, Ninth Revision, Clinical Modification code 81.01) between 1998 and 2011 who were 18 years or older at the time of admission.

OUTCOME MEASURES

Outcome measures included in-hospital charges, hospital length of stay (LOS), in-hospital mortality, and discharge disposition.

METHODS

Predictors of outcome following atlantoaxial fusion were assessed using a series of univariable analyses. Those predictors with a p-value of less than .2 were included in the final multivariable models. Independent predictors of outcome were those that were significant at an alpha level of 0.05 following inclusion in the final multivariable models. Logistic regression was used to determine predictors of in-hospital mortality and discharge disposition whereas linear regression was used to determine predictors of hospital charges and LOS. Discharge weights were used to produce generalizable results.

RESULTS

From 1998 to 2011, there were 8,914 hospitalizations recorded wherein atlantoaxial fusion was performed during the inpatient hospital stay. Of these hospitalizations, 8,189 (91.9%) met inclusion criteria. Of the study sample, 62% was white, and the majority of patients were either insured by Medicare (47.2%) or had private health insurance (35.6%). The most common comorbidity as defined by the NIS and the Elixhauser comorbidity index was hypertension (43.2%). The in-hospital mortality rate for the study population was 2.7%, and the median LOS was 6.0 days. The median total charge (inflation adjusted) per hospitalization was $73,561. Of the patients, 48.9% were discharged to home. Significant predictors of in-hospital mortality included increased age, emergent or urgent admissions, weekend admissions, congestive heart failure, coagulopathy, depression, electrolyte disorder, metastatic cancer, neurologic disorder, paralysis, and non-bleeding peptic ulcer. Many of these variables were also found to be predictors of LOS, hospital charges, and discharge disposition.

CONCLUSION

This study found that older patients and those with greater comorbidity burden had greater odds of postoperative mortality and were being discharged to another care facility, had longer hospital LOS, and incurred greater hospital charges following atlantoaxial fusion.

Does intraoperative neurophysiologic monitoring matter in noncomplex spine surgeries?

Objectives:

To determine associations between intraoperative neurophysiologic monitoring (IOM) for spinal decompressions and simple fusions with neurologic complications, length of stay, and hospitalization charges.

Methods:

Adult discharges in the Nationwide/National Inpatient Sample (NIS) (2007–2012) with spinal decompressions and simple spinal fusions were included. Revision surgeries, instrumentations, complicated approaches, and tumor- and trauma-related surgeries were excluded. Extracted data included patient demographics, medical comorbidities, primary spinal surgery type, and hospital characteristics. Bivariate and multiple regression analyses using NIS survey design variables correlated IOM use with neurologic complications, hospital charges, and length of stay.

Results:

IOM was reported in 4.9% of an estimated 1.1 million discharges in the weighted sample. Discharges reporting IOM were more often privately insured (61% vs 57%, p < 0.001) and had slightly more comorbidities (25% vs 24% with 3+ comorbidities, p = 0.01). Spinal fusions more often reported IOM than decompressions. The IOM group had fewer neurologic complications (0.8% vs 1.4% of controls) with no difference in length of stay (3.0 days for each group), but increased hospital charges (39% greater). Multiple regression adjustment showed significant associations of IOM with fewer neurologic complications (odds ratio 0.60, 95% confidence interval [CI] 0.47, 0.76, p < 0.001), while the estimated percentage of hospital charges was sizably diminished from the unadjusted analysis (IOM effect +9%, 95% CI +4%, +13%, p < 0.001), and length of stay was reduced (IOM effect −0.26 days, 95% CI −0.42, −0.11, p < 0.001).

Conclusions:

IOM was associated with better clinical outcomes and some increased hospital charges among discharges of simple spinal fusions and laminectomies in a large, multiyear, nationally representative dataset.