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.
Kalil G. Abdullah, Daniel Lubelski, Paolo G. P. Nucifora and Steven Brem
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.
Daniel Lubelski, Nicolas R. Thompson, Sachin Bansal, Thomas E. Mroz, Daniel J. Mazanec, Edward C. Benzel and Tagreed Khalaf
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.
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.
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.
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.
Daniel Lubelski, Andrew T. Healy, Alan Friedman, Dyan Ferraris, Edward C. Benzel and Richard Schlenk
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.
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.
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).
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.
Daniel Lubelski, Suzanne Tharin, John J. Como, Michael P. Steinmetz, Heather Vallier and Timothy Moore
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.
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.
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.
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.
Minimally invasive tubular resection of the anomalous transverse process in patients with Bertolotti's syndrome
Presented at the 2013 Joint Spine Section Meeting
Yumeng Li, Daniel Lubelski, Kalil G. Abdullah, Thomas E. Mroz and Michael P. Steinmetz
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.
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.
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.
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.
Daniel Lubelski, William E. McCormick, Lisa Ferrara, Edward C. Benzel and Mark Kayanja
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.
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).
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.
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.
Andrew T. Healy, Prasath Mageswaran, Daniel Lubelski, Benjamin P. Rosenbaum, Virgilio Matheus, Edward C. Benzel and Thomas E. Mroz
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.
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.
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).
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.
Matthew D. Alvin, Jacob A. Miller, Daniel Lubelski, Benjamin P. Rosenbaum, Kalil G. Abdullah, Robert G. Whitmore, Edward C. Benzel and Thomas E. Mroz
Cost-effectiveness research in spine surgery has been a prominent focus over the last decade. However, there has yet to be a standardized method developed for calculation of costs in such studies. This lack of a standardized costing methodology may lead to conflicting conclusions on the cost-effectiveness of an intervention for a specific diagnosis. The primary objective of this study was to systematically review all cost-effectiveness studies published on spine surgery and compare and contrast various costing methodologies used.
The authors performed a systematic review of the cost-effectiveness literature related to spine surgery. All cost-effectiveness analyses pertaining to spine surgery were identified using the cost-effectiveness analysis registry database of the Tufts Medical Center Institute for Clinical Research and Health Policy, and the MEDLINE database. Each article was reviewed to determine the study subject, methodology, and results. Data were collected from each study, including costs, interventions, cost calculation method, perspective of cost calculation, and definitions of direct and indirect costs if available.
Thirty-seven cost-effectiveness studies on spine surgery were included in the present study. Twenty-seven (73%) of the studies involved the lumbar spine and the remaining 10 (27%) involved the cervical spine. Of the 37 studies, 13 (35%) used Medicare reimbursements, 12 (32%) used a case-costing database, 3 (8%) used cost-to-charge ratios (CCRs), 2 (5%) used a combination of Medicare reimbursements and CCRs, 3 (8%) used the United Kingdom National Health Service reimbursement system, 2 (5%) used a Dutch reimbursement system, 1 (3%) used the United Kingdom Department of Health data, and 1 (3%) used the Tricare Military Reimbursement system. Nineteen (51%) studies completed their cost analysis from the societal perspective, 11 (30%) from the hospital perspective, and 7 (19%) from the payer perspective. Of those studies with a societal perspective, 14 (38%) reported actual indirect costs.
Changes in cost have a direct impact on the value equation for concluding whether an intervention is cost-effective. It is essential to develop a standardized, accurate means of calculating costs. Comparability and transparency are essential, such that studies can be compared properly and policy makers can be appropriately informed when making decisions for our health care system based on the results of these studies.
Benjamin D. Kuhns, Daniel Lubelski, Matthew D. Alvin, Jason S. Taub, Matthew J. McGirt, Edward C. Benzel and Thomas E. Mroz
Infections following spine surgery negatively affect patient quality of life (QOL) and impose a significant financial burden on the health care system. Postoperative wound infections occur at higher rates following dorsal cervical procedures than ventral procedures. Quantifying the health outcomes and costs associated with infections following dorsal cervical procedures may help to guide treatment strategies to minimize the deleterious consequences of these infections. Therefore, the goals of this study were to determine the cost and QOL outcomes affecting patients who developed deep wound infections following subaxial dorsal cervical spine fusions.
The authors identified 22 (4.0%) of 551 patients undergoing dorsal cervical fusions who developed deep wound infections requiring surgical debridement. These patients were individually matched with control patients who did not develop infections. Health outcomes were assessed using the EQ-5D, Pain Disability Questionnaire (PDQ), Patient Health Questionnaire (PHQ-9), and visual analog scale (VAS). QOL outcome measures were collected preoperatively and after 6 and 12 months. Health resource utilization was recorded from patient electronic medical records over an average follow-up of 18 months. Direct costs were estimated using Medicare national payment amounts, and indirect costs were based on patients' missed workdays and income.
No significant differences in preoperative QOL scores were found between the 2 cohorts. At 6 months postsurgery, the noninfection cohort had significant pre- to postoperative improvement in EQ-5D (p = 0.02), whereas the infection cohort did not (p = 0.2). The noninfection cohort also had a significantly higher 6-month postoperative EQ-5D scores than the infection cohort (p = 0.04). At 1 year postsurgery, there was no significant difference in EQ-5D scores between the groups. Health care–associated costs for the infection cohort were significantly higher ($16,970 vs $7658; p < 0.0001). Indirect costs for the infection cohort and the noninfection cohort were $6495 and $2756, respectively (p = 0.03). Adjusted for inflation, the total costs for the infection cohort were $21,778 compared with $9159 for the noninfection cohort, reflecting an average cost of $12,619 associated with developing a postoperative deep wound infection (p < 0.0001).
Dorsal cervical infections temporarily decrease patient QOL postoperatively, but with no long-term impact; they do, however, dramatically increase the cost of care. Knowledge of the financial burden of wound infections following dorsal cervical fusion may stimulate the development and use of improved prophylactic and therapeutic techniques to manage this serious complication.