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Sameer Kitab, Bryan S. Lee and Edward C. Benzel

OBJECTIVE

Using an imaging-based prospective comparative study of 709 eligible patients that was designed to assess lumbar spinal stenosis (LSS) in the ages between 16 and 82 years, the authors aimed to determine whether they could formulate radiological structural differences between the developmental and degenerative types of LSS.

METHODS

MRI structural changes were prospectively reviewed from 2 age cohorts of patients: those who presented clinically before the age of 60 years and those who presented at 60 years or older. Categorical degeneration variables at L1–S1 segments were compared. A multivariate comparative analysis of global radiographic degenerative variables and spinal dimensions was conducted in both cohorts. The age at presentation was correlated as a covariable.

RESULTS

A multivariate analysis demonstrated no significant between-groups differences in spinal canal dimensions and stenosis grades in any segments after age was adjusted for. There were no significant variances between the 2 cohorts in global degenerative variables, except at the L4–5 and L5–S1 segments, but with only small effect sizes. Age-related degeneration was found in the upper lumbar segments (L1–4) more than the lower lumbar segments (L4–S1). These findings challenge the notion that stenosis at L4–5 and L5–S1 is mainly associated with degenerative LSS.

CONCLUSIONS

Integration of all the morphometric and qualitative characteristics of the 2 LSS cohorts provides evidence for a developmental background for LSS. Based on these findings the authors propose the concept of LSS as a developmental syndrome with superimposed degenerative changes. Further studies can be conducted to clarify the clinical definition of LSS and appropriate management approaches.

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The effect of C2–3 disc angle on postoperative adverse events in cervical spondylotic myelopathy

Presented at the 2018 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves

Bryan S. Lee, Kevin M. Walsh, Daniel Lubelski, Konrad D. Knusel, Michael P. Steinmetz, Thomas E. Mroz, Richard P. Schlenk, Iain H. Kalfas and Edward C. Benzel

OBJECTIVE

Complete radiographic and clinical evaluations are essential in the surgical treatment of cervical spondylotic myelopathy (CSM). Prior studies have correlated cervical sagittal imbalance and kyphosis with disability and worse health-related quality of life. However, little is known about C2–3 disc angle and its correlation with postoperative outcomes. The present study is the first to consider C2–3 disc angle as an additional radiographic predictor of postoperative adverse events.

METHODS

A retrospective chart review was performed to identify patients with CSM who underwent surgeries from 2010 to 2014. Data collected included demographics, baseline presenting factors, and postoperative outcomes. Cervical sagittal alignment variables were measured using the preoperative and postoperative radiographs. Univariable logistic regression analyses were used to explore the association between dependent and independent variables, and a multivariable logistic regression model was created using stepwise variable selection.

RESULTS

The authors identified 171 patients who had complete preoperative and postoperative radiographic and outcomes data. The overall rate of postoperative adverse events was 33% (57/171), and postoperative C2–3 disc angle, C2–7 sagittal vertical axis, and C2–7 Cobb angle were found to be significantly associated with adverse events. Inclusion of postoperative C2–3 disc angle in the analysis led to the best prediction of adverse events. The mean postoperative C2–3 disc angle for patients with any postoperative adverse event was 32.3° ± 17.2°, and the mean for those without any adverse event was 22.4° ± 11.1° (p < 0.0001).

CONCLUSIONS

In the present retrospective analysis of postoperative adverse events in patients with CSM, the authors found a significant association between C2–3 disc angle and postoperative adverse events. They propose that C2–3 disc angle be used as an additional parameter of cervical spinal sagittal alignment and predictor for operative outcomes.

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Jay M. Levin, Robert D. Winkelman, Joseph E. Tanenbaum, Edward C. Benzel, Thomas E. Mroz and Michael P. Steinmetz

OBJECTIVE

The Patient Experience of Care, composed of 9 dimensions derived from the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey, is being used by the Centers for Medicare & Medicaid Services to adjust hospital reimbursement. Currently, there are minimal data on how scores on the constituent HCAHPS items impact the global dimension of satisfaction, the Overall Hospital Rating (OHR). The purpose of this study was to determine the key drivers of overall patient satisfaction in the setting of inpatient lumbar spine surgery.

METHODS

Demographic and preoperative patient characteristics were obtained. Patients selecting a top-box score for OHR (a 9 or 10 of 10) were considered to be satisfied with their hospital experience. A baseline multivariable logistic regression model was then developed to analyze the association between patient characteristics and top-box OHR. Then, multivariable logistic regression models adjusting for patient-level covariates were used to determine the association between individual components of the HCAHPS survey and a top-box OHR.

RESULTS

A total of 453 patients undergoing lumbar spine surgery were included, 80.1% of whom selected a top-box OHR. Diminishing overall health status (OR 0.63, 95% CI 0.43–0.91) was negatively associated with top-box OHR. After adjusting for potential confounders, the survey items that were associated with the greatest increased odds of selecting a top-box OHR were: staff always did everything they could to help with pain (OR 12.5, 95% CI 6.6–23.7), and nurses were always respectful (OR 11.0, 95% CI 5.3–22.6).

CONCLUSIONS

Patient experience of care is increasingly being used to determine hospital and physician reimbursement. The present study analyzed the key drivers of patient experience among patients undergoing lumbar spine surgery and found several important associations. Patient overall health status was associated with top-box OHR. After adjusting for potential confounders, staff always doing everything they could to help with pain and nurses always being respectful were the strongest predictors of overall satisfaction in this population. These findings highlight opportunities for quality improvement efforts in the spine care setting.

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Varun R. Kshettry, Andrew T. Healy, Robb Colbrunn, Dylan T. Beckler, Edward C. Benzel and Pablo F. Recinos

OBJECTIVE

The far lateral transcondylar approach to the ventral foramen magnum requires partial resection of the occipital condyle. Early biomechanical studies suggest that occipitocervical (OC) fusion should be considered if 50% of the condyle is resected. In clinical practice, however, a joint-sparing condylectomy has often been employed without the need for OC fusion. The biomechanics of the joint-sparing technique have not been reported. Authors of the present study hypothesized that the clinically relevant joint-sparing condylectomy would result in added stability of the craniovertebral junction as compared with earlier reports.

METHODS

Multidirectional in vitro flexibility tests were performed using a robotic spine-testing system on 7 fresh cadaveric spines to assess the effect of sequential unilateral joint-sparing condylectomy (25%, 50%, 75%, 100%) in comparison with the intact state by using cardinal direction and coupled moments combined with a simulated head weight “follower load.”

RESULTS

The percent change in range of motion following sequential condylectomy as compared with the intact state was 5.2%, 8.1%, 12.0%, and 27.5% in flexion-extension (FE); 8.4%, 14.7%, 39.1%, and 80.2% in lateral bending (LB); and 24.4%, 31.5%, 49.9%, and 141.1% in axial rotation (AR). Only values at 100% condylectomy were statistically significant (p < 0.05). With coupled motions, however, −3.9%, 6.6%, 35.8%, and 142.4% increases in AR+F and 27.3%, 32.7%, 77.5%, and 175.5% increases in AR+E were found. Values for 75% and 100% condyle resection were statistically significant in AR+E.

CONCLUSIONS

When tested in the traditional cardinal directions, a 50% joint-sparing condylectomy did not significantly increase motion. However, removing 75% of the condyle may necessitate fusion, as a statistically significant increase in motion was found when E was coupled with AR. Clinical correlation is ultimately needed to determine the need for OC fusion.

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Jacob A. Miller, Ehsan H. Balagamwala, Camille A. Berriochoa, Lilyana Angelov, John H. Suh, Edward C. Benzel, Alireza M. Mohammadi, Todd Emch, Anthony Magnelli, Andrew Godley, Peng Qi and Samuel T. Chao

OBJECTIVE

Spine stereotactic radiosurgery (SRS) is a safe and effective treatment for spinal metastases. However, it is unknown whether this highly conformal radiation technique is suitable at instrumented sites given the potential for microscopic disease seeding. The authors hypothesized that spinal decompression with instrumentation is not associated with increased local failure (LF) following SRS.

METHODS

A 2:1 propensity-matched retrospective cohort study of patients undergoing SRS for spinal metastasis was conducted. Patients with less than 1 month of radiographic follow-up were excluded. Each SRS treatment with spinal decompression and instrumentation was propensity matched to 2 controls without decompression or instrumentation on the basis of demographic, disease-related, dosimetric, and treatment-site characteristics. Standardized differences were used to assess for balance between matched cohorts.

The primary outcome was the 12-month cumulative incidence of LF, with death as a competing risk. Lesions demonstrating any in-field progression were considered LFs. Secondary outcomes of interest were post-SRS pain flare, vertebral compression fracture, instrumentation failure, and any Grade ≥ 3 toxicity. Cumulative incidences analysis was used to estimate LF in each cohort, which were compared via Gray’s test. Multivariate competing-risks regression was then used to adjust for prespecified covariates.

RESULTS

Of 650 candidates for the control group, 166 were propensity matched to 83 patients with instrumentation. Baseline characteristics were well balanced. The median prescription dose was 16 Gy in each cohort. The 12-month cumulative incidence of LF was not statistically significantly different between cohorts (22.8% [instrumentation] vs 15.8% [control], p = 0.25). After adjusting for the prespecified covariates in a multivariate competing-risks model, decompression with instrumentation did not contribute to a greater risk of LF (HR 1.21, 95% CI 0.74–1.98, p = 0.45). The incidences of post-SRS pain flare (11% vs 14%, p = 0.55), vertebral compression fracture (12% vs 22%, p = 0.04), and Grade ≥ 3 toxicity (1% vs 1%, p = 1.00) were not increased at instrumented sites. No instrumentation failures were observed.

CONCLUSIONS

In this propensity-matched analysis, LF and toxicity were similar among cohorts, suggesting that decompression with instrumentation does not significantly impact the efficacy or safety of spine SRS. Accordingly, spinal instrumentation may not be a contraindication to SRS. Future studies comparing SRS to conventional radiotherapy at instrumented sites in matched populations are warranted.

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Roy Xiao, Jacob A. Miller, Navin C. Sabharwal, Daniel Lubelski, Vincent J. Alentado, Andrew T. Healy, Thomas E. Mroz and Edward C. Benzel

OBJECTIVE

Improvements in imaging technology have steadily advanced surgical approaches. Within the field of spine surgery, assistance from the O-arm Multidimensional Surgical Imaging System has been established to yield superior accuracy of pedicle screw insertion compared with freehand and fluoroscopic approaches. Despite this evidence, no studies have investigated the clinical relevance associated with increased accuracy. Accordingly, the objective of this study was to investigate the clinical outcomes following thoracolumbar spinal fusion associated with O-arm–assisted navigation. The authors hypothesized that increased accuracy achieved with O-arm–assisted navigation decreases the rate of reoperation secondary to reduced hardware failure and screw misplacement.

METHODS

A consecutive retrospective review of all patients who underwent open thoracolumbar spinal fusion at a single tertiary-care institution between December 2012 and December 2014 was conducted. Outcomes assessed included operative time, length of hospital stay, and rates of readmission and reoperation. Mixed-effects Cox proportional hazards modeling, with surgeon as a random effect, was used to investigate the association between O-arm–assisted navigation and postoperative outcomes.

RESULTS

Among 1208 procedures, 614 were performed with O-arm–assisted navigation, 356 using freehand techniques, and 238 using fluoroscopic guidance. The most common indication for surgery was spondylolisthesis (56.2%), and most patients underwent a posterolateral fusion only (59.4%). Although O-arm procedures involved more vertebral levels compared with the combined freehand/fluoroscopy cohort (4.79 vs 4.26 vertebral levels; p < 0.01), no significant differences in operative time were observed (4.40 vs 4.30 hours; p = 0.38). Patients who underwent an O-arm procedure experienced shorter hospital stays (4.72 vs 5.43 days; p < 0.01). O-arm–assisted navigation trended toward predicting decreased risk of spine-related readmission (0.8% vs 2.2%, risk ratio [RR] 0.37; p = 0.05) and overall readmissions (4.9% vs 7.4%, RR 0.66; p = 0.07). The O-arm was significantly associated with decreased risk of reoperation for hardware failure (2.9% vs 5.9%, RR 0.50; p = 0.01), screw misplacement (1.6% vs 4.2%, RR 0.39; p < 0.01), and all-cause reoperation (5.2% vs 10.9%, RR 0.48; p < 0.01). Mixed-effects Cox proportional hazards modeling revealed that O-arm–assisted navigation was a significant predictor of decreased risk of reoperation (HR 0.49; p < 0.01). The protective effect of O-arm–assisted navigation against reoperation was durable in subset analysis of procedures involving < 5 vertebral levels (HR 0.44; p = 0.01) and ≥ 5 levels (HR 0.48; p = 0.03). Further subset analysis demonstrated that O-arm–assisted navigation predicted decreased risk of reoperation among patients undergoing posterolateral fusion only (HR 0.39; p < 0.01) and anterior lumbar interbody fusion (HR 0.22; p = 0.03), but not posterior/transforaminal lumbar interbody fusion.

CONCLUSIONS

To the authors' knowledge, the present study is the first to investigate clinical outcomes associated with O-arm–assisted navigation following thoracolumbar spinal fusion. O-arm–assisted navigation decreased the risk of reoperation to less than half the risk associated with freehand and fluoroscopic approaches. Future randomized controlled trials to corroborate the findings of the present study are warranted.

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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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Dara Bakar, Joseph E. Tanenbaum, Kevin Phan, Vincent J. Alentado, Michael P. Steinmetz, Edward C. Benzel and Thomas E. Mroz

OBJECTIVE

The aim of this study was to systematically review the literature on reported outcomes following decompression surgery for spinal metastases.

METHODS

The authors conducted MEDLINE, Scopus, and Web of Science database searches for studies reporting clinical outcomes and complications associated with decompression surgery for metastatic spinal tumors. Both retrospective and prospective studies were included. After meeting inclusion criteria, articles were categorized based on the following reported outcomes: survival, ambulation, surgical technique, neurological function, primary tumor histology, and miscellaneous outcomes.

RESULTS

Of the 4148 articles retrieved from databases, 36 met inclusion criteria. Of those included, 8 were prospective studies and 28 were retrospective studies. The year of publication ranged from 1992 to 2015. Study size ranged from 21 to 711 patients. Three studies found that good preoperative Karnofsky Performance Status (KPS ≥ 80%) was a significant predictor of survival. No study reported a significant effect of time-to-surgery following the onset of spinal cord compression symptoms on survival. Three studies reported improvement in neurological function following surgery. The most commonly cited complication was wound infection or dehiscence (22 studies). Eight studies reported that preoperative ambulatory or preoperative motor status was a significant predictor of postoperative ambulatory status. A wide variety of surgical techniques were reported: posterior decompression and stabilization, posterior decompression without stabilization, and posterior decompression with total or subtotal tumor resection. Although a wide range of functional scales were used to assess neurological outcomes, four studies used the American Spinal Injury Association (ASIA) Impairment Scale to assess neurological function. Four studies reported the effects of radiation therapy and local disease control for spinal metastases. Two studies reported that the type of treatment was not significantly associated with the rate of local control. The most commonly reported primary tumor types included lung cancer, prostate cancer, breast cancer, renal cancer, and gastrointestinal cancer.

CONCLUSIONS

This study reports a systematic review of the literature on decompression surgery for spinal metastases. The results of this study can help educate surgeons on the previously published predictors of outcomes following decompression surgery for metastatic spinal disease. However, the authors also identify significant gaps in the literature and the need for future studies investigating the optimal practice with regard to decompression surgery for spinal metastases.