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Surgical management of giant presacral schwannoma: systematic review of published cases and meta-analysis

Presented at the 2019 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves

Zach Pennington, Erick M. Westbroek, A. Karim Ahmed, Ethan Cottrill, Daniel Lubelski, Matthew L. Goodwin and Daniel M. Sciubba

OBJECTIVE

Giant presacral schwannomas are rare sacral tumors found in less than 1 of every 40,000 hospitalizations. Current management of these tumors is based solely upon case reports and small case series. In this paper the authors report the results of a systematic review of the available English literature on presacral schwannoma, focused on identifying the influence of tumor size, tumor morphology, surgical approach, and extent of resection (EOR) on recurrence-free survival and postoperative complications.

METHODS

The medical literature (PubMed and EMBASE) was queried for reports of surgically managed sacral schwannoma, either involving 2 or more contiguous vertebral levels or with a diameter ≥ 5 cm. Tumor size and morphology, surgical approach, EOR, intraoperative and postoperative complications, and survival data were recorded.

RESULTS

Seventy-six articles were included, covering 123 unique patients (mean age 44.1 ± 1.4 years, 50.4% male). The most common presenting symptoms were leg pain (28.7%), lower back pain (21.3%), and constipation (15.7%). Most surgeries used an open anterior-only (40.0%) or posterior-only (30%) approach. Postoperative complications occurred in 25.6% of patients and local recurrence was noted in 5.4%. En bloc resection significantly improved progression-free survival relative to subtotal resection (p = 0.03). No difference existed between en bloc and gross-total resection (GTR; p = 0.25) or among the surgical approaches (p = 0.66). Postoperative complications were more common following anterior versus posterior approaches (p = 0.04). Surgical blood loss was significantly correlated with operative duration and tumor volume on multiple linear regression (both p < 0.001).

CONCLUSIONS

Presacral schwannoma can reasonably be treated with either en bloc or piecemeal GTR. The approach should be dictated by lesion morphology, and recurrence is infrequent. Anterior approaches may increase the risk of postoperative complications.

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Kalil G. Abdullah, Daniel Lubelski, Paolo G. P. Nucifora and Steven Brem

Diffusion tensor imaging (DTI) is increasingly used in the resection of both high- and low-grade gliomas. Whereas conventional MRI techniques provide only anatomical information, DTI offers data on CNS connectivity by enabling visualization of important white matter tracts in the brain. Importantly, DTI allows neurosurgeons to better guide their surgical approach and resection. Here, the authors review basic scientific principles of DTI, include a primer on the technology and image acquisition, and outline the modality's evolution as a frequently used tool for glioma resection. Current literature supporting its use is summarized, highlighting important clinical studies on the application of DTI in preoperative planning for glioma resection, preoperative diagnosis, and postoperative outcomes. The authors conclude with a review of future directions for this technology.

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Matthew D. Alvin, Daniel Lubelski, Edward C. Benzel and Thomas E. Mroz

Cervical spondylotic myelopathy (CSM) often can be surgically treated by either ventral or dorsal decompression and fusion. However, there is a lack of high-level evidence on the relative advantages and disadvantages for these treatments of CSM. The authors' goal was to provide a comprehensive review of the relative benefits of ventral versus dorsal fusion in terms of quality of life (QOL) outcomes, complications, and costs. They reviewed 7 studies on CSM published between 2003 and 2013 and summarized the findings for each category. Both procedures have been shown to lead to statistically significant improvement in clinical outcomes for patients. Ventral fusion surgery has been shown to yield better QOL outcomes than dorsal fusion surgery. Complication rates for ventral fusion surgery range from 11% to 13.6%, whereas those for dorsal fusion surgery range from 16.4% to 19%. Larger randomized controlled trials are needed, with particular emphasis on QOL and minimum clinically important differences.

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Daniel Lubelski, Nicolas R. Thompson, Sachin Bansal, Thomas E. Mroz, Daniel J. Mazanec, Edward C. Benzel and Tagreed Khalaf

OBJECT

The goal of this study was to determine whether pretreatment depression is predictive of quality of life (QOL) improvement for patients with lumbar spinal stenosis (LSS) who are treated conservatively.

METHODS

This retrospective cohort study included patients with LSS and concordant neurogenic claudication who were treated nonoperatively at a single institution between September 2010 and March 2013. Patient QOL measures were recorded pretreatment and then 4 months after treatment. Pretreatment depression was assessed using the Patient Health Questionnaire–9 (PHQ-9). Successful outcome was defined as posttreatment improvement in EuroQol-5D (EQ-5D) index or in Pain and Disability Questionnaire (PDQ) scores. Regression analysis was performed to identify independent predictors of outcome while controlling for confounding variables.

RESULTS

A total of 502 patients were included in the study. The average age for these patients was 66.1 years, with 51% female and 90.6% white. After adjusting for baseline demographic and clinical variables, there was a statistically significant association between baseline PHQ-9 score and posttreatment change in EQ-5D index (β = −0.007, p = 0.0002). All other things being equal, a patient with a baseline PHQ-9 score of 0 (no depression) would be expected to improve in the EQ-5D index by 0.14 points (greater than the minimum clinically important difference) more than would a patient with a baseline PHQ-9 score of 20 (major depression). There was no significant association between baseline PHQ-9 score and change in Pain and Disability Questionnaire scores.

CONCLUSIONS

When controlling for other baseline characteristics, severely depressed patients with LSS who are treated nonoperatively have significantly less improvement in their QOL compared with those with little or no depression. These data are similar to the negative predictive effects of depression on posttreatment QOL following lumbar fusion surgery.

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Daniel Lubelski, Andrew T. Healy, Alan Friedman, Dyan Ferraris, Edward C. Benzel and Richard Schlenk

OBJECTIVE

Neurosurgery is among the most competitive residencies, as evidenced by the high number of applicants for relatively few positions. Although it is important to recruit candidates who have the intellectual capacity and drive to succeed, traditional objective selection criteria, such as US Medical Licensing Examination (USMLE) (also known as Step 1) score, number of publications, and class ranking, have not been shown to consistently predict clinical and academic success. Furthermore, these traditional objective parameters have not been associated with specific personality traits.

METHODS

The authors sought to determine the efficacy of a personality assessment in the selection of neurosurgery residents. Specifically, the aim was to determine the correlation between traditional measures used to evaluate an applicant (e.g., USMLE score, number of publications, MD/PhD status) and corresponding validated personality traits.

RESULTS

Fifty-four neurosurgery residency applicants were interviewed at the Cleveland Clinic during the 2014–2015 application cycle. No differences in validated personality scores were identified between the 46 MD applicants and 8 MD/PhD applicants. The mean USMLE score (± SD) was 252.3 ± 11.9, and those in the high-USMLE-score category (USMLE score ≥ 260) had a significantly lower “imaginative” score (a stress measure of eccentric thinking and impatience with those who think more slowly). The average number of publications per applicant was 8.6 ± 7.9, and there was a significant positive correlation (r = 0.339, p = 0.016) between greater number of publications and a higher “adjustment” score (a measure of being even-tempered, having composure under pressure). Significant negative correlations existed between the total number of publications and the “excitable” score (a measure of being emotionally volatile) (r = −0.299, p = 0.035) as well as the “skeptical” score (measure of being sensitive to criticism) (r = −0.325, p = 0.021). The average medical school rank was 25.8, and medical school rankings were positively correlated with the “imaginative” score (r = 0.287, p = 0.044).

CONCLUSIONS

This is the first study to investigate the use of personality scores in the selection of neurosurgical residents. The use of personality assessments has the potential to provide insight into an applicant's future behavior as a resident and beyond. This information may be useful in the selection of neurosurgical residents and can be further used to customize the teaching of residents and for enabling them to recognize their own strengths and weaknesses for self-improvement.

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Yumeng Li, Daniel Lubelski, Kalil G. Abdullah, Thomas E. Mroz and Michael P. Steinmetz

Object

Bertolotti's syndrome consists of low-back pain caused by lumbosacral transitional vertebrae (LSTVs) and LSTV-associated biomechanical spinal changes. There is a lack of consensus regarding the cause, clinical significance, and treatment of this condition. The authors aim to characterize the clinical presentation of patients with Bertolotti's syndrome and describe a minimally invasive surgical treatment for this condition.

Methods

Seven patients who underwent minimally invasive paramedian tubular-based resection of the LSTV for Bertolotti's syndrome were identified over the course of 5 years. Diagnosis was based on patient history of chronic low-back pain, radiographic findings of LSTV, and pain relief on trigger-site injection with steroid and/or anesthetics. Electronic medical records were reviewed to identify demographics, operative data, and outcomes.

Results

All patients presented with severe, chronic low-back pain lasting an average of 8 years that was resistant to nonoperative care. At presentation, 6 (86%) of 7 patients experienced radicular pain that was ipsilateral to the LSTV. Radiographic evidence showed a presence of LSTV in all patients on the left (43%), right (29%), or bilaterally (29%). Degenerative disc changes at the L4–5 level immediately above the anomalous LSTV were observed in 6 of 7 (86%) patients; these changes were not seen at the level below the LSTV. Following pseudo-joint injection, all patients experienced temporary relief of their symptoms. All patients underwent a minimally invasive, paramedian tubular-based approach for resection of the LSTV. Three (43%) of 7 patients reported complete resolution of low-back pain, 2 (29%) of 7 patients had reduced low-back pain, and 2 patients (29%) experienced initial relief but return of low-back pain at 1 and 4 years postoperatively. Three (50%) of the 6 patients with radicular pain had complete relief of this symptom. The median follow-up time was 12 months. No intraoperative complication was reported. Two (29%) of 7 patients developed postoperative complications including one with a wound hematoma and another with new L-5 radiculopathy that resolved 2 years after surgery.

Conclusions

Diagnosis of Bertolotti's syndrome should be considered with adequate patient history, imaging studies, and diagnostic injections. A minimally invasive surgical approach for resection of the LSTV is presented here for symptomatic treatment of select patients with Bertolotti's syndrome whose conditions are refractory to conventional therapy and who have pain that can be attributed to the LSTV. Several short-term complications were noted with this procedure, but overall this procedure is effective for treating symptoms related to Bertolotti's syndrome.

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Andrew T. Healy, Prasath Mageswaran, Daniel Lubelski, Benjamin P. Rosenbaum, Virgilio Matheus, Edward C. Benzel and Thomas E. Mroz

OBJECT

The degenerative process of the spinal column results in instability followed by a progressive loss of segmental motion. Segmental degeneration is associated with intervertebral disc and facet changes, which can be quantified. Correlating this degeneration with clinical segmental motion has not been investigated in the thoracic spine. The authors sought to determine if imaging-determined degeneration would correlate with native range of motion (ROM) or the change in ROM after decompressive procedures, potentially guiding clinical decision making in the setting of spine trauma or following decompressive procedures in the thoracic spine.

METHODS

Multidirectional flexibility tests with image analysis were performed on thoracic cadaveric spines with intact ib cage. Specimens consisted of 19 fresh frozen human cadaveric spines, spanning C-7 to L-1. ROM was obtained for each specimen in axial rotation (AR), flexion-extension (FE), and lateral bending (LB) in the intact state and following laminectomy, unilateral facetectomy, and unilateral costotransversectomy performed at either T4–5 (in 9 specimens) or T8–9 (in 10 specimens). Image grading of segmental degeneration was performed utilizing 3D CT reconstructions. Imaging scores were obtained for disc space degeneration, which quantified osteophytes, narrowing, and endplate sclerosis, all contributing to the Lane disc summary score. Facet degeneration was quantified using the Weishaupt facet summary score, which included the scoring of facet osteophytes, narrowing, hypertrophy, subchondral erosions, and cysts.

RESULTS

The native ROM of specimens from T-1 to T-12 (n = 19) negatively correlated with age in AR (Pearson’s r coefficient = -0.42, p = 0.070) and FE (r = -0.42, p = 0.076). When regional ROM (across 4 adjacent segments) was considered, the presence of disc osteophytes negatively correlated with FE (r = −0.69, p = 0.012), LB (r = −0.82, p = 0.001), and disc narrowing trended toward significance in AR (r = −0.49, p = 0.107). Facet characteristics, scored using multiple variables, showed minimal correlation to native ROM (r range from −0.45 to +0.19); however, facet degeneration scores at the surgical level revealed strong negative correlations with regional thoracic stability following decompressive procedures in AR and LB (Weishaupt facet summary score: r = −0.52 and r = −0.71; p = 0.084 and p = 0.010, respectively). Disc degeneration was not correlated (Lane disc summary score: r = −0.06, p = 0.861).

CONCLUSIONS

Advanced age was the most important determinant of decreasing native thoracic ROM, whereas imaging characteristics (T1–12) did not correlate with the native ROM of thoracic specimens with intact rib cages. Advanced facet degeneration at the surgical level did correlate to specimen stability following decompressive procedures, and is likely indicative of the terminal stages of segmental degeneration.

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Daniel Lubelski, Suzanne Tharin, John J. Como, Michael P. Steinmetz, Heather Vallier and Timothy Moore

OBJECTIVE

Few studies have investigated the advantages of early spinal stabilization in the patient with polytrauma in terms of reduction of morbidity and mortality. Previous analyses have shown that early stabilization may reduce ICU stay, with no effect on complication rates.

METHODS

The authors prospectively observed 340 polytrauma patients with an Injury Severity Score (ISS) of greater than 16 at a single Level 1 trauma center who were treated in accordance with a protocol termed “early appropriate care,” which emphasizes operative treatment of various fractures within 36 hours of injury. Of these patients, 46 had upper thoracic and/or cervical spine injuries. The authors retrospectively compared patients treated according to protocol versus those who were not. Continuous variables were compared using independent t-tests and categorical variables using Fisher’s exact test. Logistic regression analysis was performed to account for baseline confounding factors.

RESULTS

Fourteen of 46 patients (30%) did not undergo surgery within 36 hours. These patients were significantly more likely to be older than those in the protocol group (53 vs 38 years, p = 0.008) and have greater body mass index (BMI; 33 vs 27, p = 0.02), and they were less likely to have a spinal cord injury (SCI) (82% did not have an SCI vs 44% in the protocol group, p = 0.04). In terms of outcomes, patients in the protocol-breach group had significantly more total ventilator days (13 vs 6 days, p = 0.02) and total ICU days (16 vs 9 days, p = 0.03). Infection rates were 14% in the protocol-breach group and 3% in the protocol group (p = 0.2) Total complications trended toward being statistically significantly more common in the protocol-breach group (57% vs 31%). After controlling for potential confounding variables by logistic regression (including age, sex, BMI, race, and SCI), total complications were significantly (p < 0.05) greater in the protocol-breach group (OR 29, 95% CI 1.9–1828). This indicates that the odds of developing “any complication” were 29 times greater if treatment was delayed more than 36 hours.

CONCLUSIONS

Early surgical stabilization in the polytrauma patient with a cervical or upper thoracic spine injury is associated with fewer complications and improved outcomes. Hospitals may consider the benefit of protocols that promote early stabilization in this patient population.

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Daniel Lubelski, William E. McCormick, Lisa Ferrara, Edward C. Benzel and Mark Kayanja

Object

The authors conducted a study to compare biomechanical effects on the cervical spine of bridging fixation and intermediate fixation techniques, in both fixed and dynamic modes.

Methods

A biaxial, servohydraulic machine biomechanically tested 23 human cervical spines for stiffness and strain in compression, extension, flexion, and lateral bending through 3 specimen states: 1) intact, 2) defect (corpectomy and discectomy), and 3) grafting with plate application in 1 of 4 constructs: C3–7 dynamized long strut (DLS), C3–7 fixed long strut (FLS), C3–5–7 dynamized multisegment (DMS), and C3–5–7 fixed multisegment (FMS).

Results

Compared with FMS, FLS had significantly greater strain in extension (at C-3 and at the rostral and caudal parts of the graft) and in lateral bending (at C-3 and at the caudal part of the graft). Fixed (FLS and FMS) constructs had greater flexion stiffness than did dynamized (DLS and DMS) constructs and showed a trend toward greater lateral bending stiffness. Instrumentation revealed greater extension strain with the long fixed (FLS and DLS) constructs than with the multifixed (FMS and FMS) constructs at the rostral and caudal parts of the graft but no significant differences between the dynamized (DLS and DMS) and fixed (FLS and FMS) constructs.

Conclusions

Multisegmental fixation provided greater stabilizing forces than did bridging constructs for both dynamized and fixed plates. Use of multisegmental fixation can potentially decrease strain at the screw-plate interface and reduce the rate of hardware failure.

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Daniel Lubelski, Roy Xiao, Debraj Mukherjee, William W. Ashley, Timothy Witham, Henry Brem, Judy Huang and Stacey Quintero Wolfe

OBJECTIVE

Neurosurgery seeks to attract the best and brightest medical students; however, there is often a lack of early exposure to the field, among other possible barriers. The authors sought to identify successful practices that can be implemented to improve medical student recruitment to neurosurgery.

METHODS

United States neurosurgery residency program directors were surveyed to determine the number of medical student rotators and medical students matching into a neurosurgery residency from their programs between 2010 and 2016. Program directors were asked about the ways their respective institutions integrated medical students into departmental clinical and research activities.

RESULTS

Complete responses were received from 30/110 institutions. Fifty-two percent of the institutions had neurosurgery didactic lectures for 1st- and 2nd-year medical students (MS1/2), and 87% had didactics for MS3/4. Seventy-seven percent of departments had a neurosurgery interest group, which was the most common method used to integrate medical students into the department. Other forms of outreach included formal mentorship programs (53%), lecture series (57%), and neurosurgery anatomy labs (40%). Seventy-three percent of programs provided research opportunities to medical students, and 57% indicated that the schools had a formal research requirement. On average, 3 medical students did a rotation in each neurosurgery department and 1 matched into neurosurgery each year. However, there was substantial variability among programs. Over the 2010–2016 period, the responding institutions matched as many as 4% of the graduating class into neurosurgery per year, whereas others matched 0%–1%. Departments that matched a greater (≥ 1% per year) number of medical students into neurosurgery were significantly more likely to have a neurosurgery interest group and formal research requirements. A greater percentage of high-matching programs had neurosurgery mentorship programs, lecture series, and cadaver training opportunities compared to the other institutions.

CONCLUSIONS

In recent decades, the number of applicants to neurosurgery has decreased. A major deterrent may be the delayed exposure of medical students to neurosurgery. Institutions with early preclinical exposure, active neurosurgery interest groups, research opportunities, and strong mentorship recruit and match more students into neurosurgery. Implementing such initiatives on a national level may increase the number of highly qualified medical students pursuing neurosurgery.