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George M. Ghobrial, Christopher M. Maulucci, Mitchell Maltenfort, Richard T. Dalyai, Alexander R. Vaccaro, Michael G. Fehlings, John Street, Paul M. Arnold and James S. Harrop

Object

Thoracolumbar spine injuries are commonly encountered in patients with trauma, accounting for almost 90% of all spinal fractures. Thoracolumbar burst fractures comprise a high percentage of these traumatic fractures (45%), and approximately half of the patients with this injury pattern are neurologically intact. However, a debate over complication rates associated with operative versus nonoperative management of various thoracolumbar fracture morphologies is ongoing, particularly concerning those patients presenting without a neurological deficit.

Methods

A MEDLINE search for pertinent literature published between 1966 and December 2013 was conducted by 2 authors (G.G. and R.D.), who used 2 broad search terms to maximize the initial pool of manuscripts for screening. These terms were “operative lumbar spine adverse events” and “nonoperative lumbar spine adverse events.”

Results

In an advanced MEDLINE search of the term “operative lumbar spine adverse events” on January 8, 2014, 1459 results were obtained. In a search of “nonoperative lumbar spine adverse events,” 150 results were obtained. After a review of all abstracts for relevance to traumatic thoracolumbar spinal injuries, 62 abstracts were reviewed for the “operative” group and 21 abstracts were reviewed for the “nonoperative” group. A total of 14 manuscripts that met inclusion criteria for the operative group and 5 manuscripts that met criteria for the nonoperative group were included.

There were a total of 919 and 436 patients in the operative and nonoperative treatment groups, respectively. There were no statistically significant differences between the groups with respect to age, sex, and length of stay. The mean ages were 43.17 years in the operative and 34.68 years in the nonoperative groups. The majority of patients in both groups were Frankel Grade E (342 and 319 in operative and nonoperative groups, respectively). Among the studies that reported the data, the mean length of stay was 14 days in the operative group and 20.75 in the nonoperative group.

The incidence of all complications in the operative and nonoperative groups was 300 (32.6%) and 21 (4.8%), respectively (p = 0.1065). There was no significant difference between the 2 groups with respect to the incidence of pulmonary, thromboembolic, cardiac, and gastrointestinal complications. However, the incidence of infections (pneumonia, urinary tract infection, wound infection, and sepsis) was significantly higher in the operative group (p = 0.000875). The incidence of instrumentation failure and need for revision surgery was 4.35% (40 of 919), a significant morbidity, and an event unique to the operative category (p = 0.00396).

Conclusions

Due to the limited number of high-quality studies, conclusions related to complication rates of operative and nonoperative management of thoracolumbar traumatic injuries cannot be definitively made. Further prospective, randomized studies of operative versus nonoperative management of thoracolumbar and lumbar spine trauma, with standardized definitions of complications and matched patient cohorts, will aid in properly defining the risk-benefit ratio of surgery for thoracolumbar spine fractures.

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Faisal S. Taleb, Abhijit Guha, Paul M. Arnold, Michael G. Fehlings and Eric M. Massicotte

Object

Patients with neurofibromatosis Type 1 (NF-1) at the cervical spine present significant surgical challenges due to neural compression, multiplicity of tumors, and complex spinal deformities. Iatrogenic instability following resection of tumors is underappreciated in the literature. The focus of this study was to understand the indications for stabilization in this specific group of patients.

Methods

The authors performed a retrospective review of 20 cases involving NF-1 patients with symptomatic cervical spine neurofibromas who underwent surgical decompression and tumor resection, with or without instrumentation, between 1991 and 2008. They also included 2 additional cases involving patients treated before 1991. Imaging findings and data pertaining to clinical presentation, intraoperative management, and postoperative assessment were compiled to clarify the indications for stabilization. An ordinal pain scale based on patient self-assessment was used. Neurological function was evaluated using American Spinal Injury Association Impairment Scale scores.

Results

The patient group comprised 13 men and 9 women. Their median age at presentation was 42.5 years; their median age at initial diagnosis of NF-1 was 30 years (range 8–74 years). The median duration of follow-up (since presentation) was 7 years (range 1–32 years). Progressive myelopathy was the main presenting symptom. Spinal cord compression was identified in 13 patients on presentation. Complete removal of the symptomatic tumors was performed in 11 patients. Ten patients underwent instrumented fusion during their first surgery. Six of these 10 required a second surgery—with fixation in 4 cases and without in 2. Of the 12 patients who did not receive instrumented fusion in their first surgery, 8 required a second surgery—with fixation in 5 cases and without in 3. Neurological deterioration due to progressive deformity was the indication for the second surgery in 3 of the 5 patients who required instrumented fusion only in their second surgery; the other 2 patients presented with neurological deterioration secondary to tumor progression. Four patients needed a third operation and instrumented fusion: 3 for deformity-related deficit and 1 for tumor progression. Based on the latest follow-up, 21 patients were stable clinically and radiologically, and 1 patient had died.

Conclusions

This specific group of patients represents a significant surgical challenge. In this retrospective analysis, emphasis is placed on early stabilization of the cervical spine to prevent late deformity as part of the comprehensive management of patients with NF-1.

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Arjun Sahgal, Mark Bilsky, Eric L. Chang, Lijun Ma, Yoshiya Yamada, Laurence D. Rhines, Daniel Létourneau, Matthew Foote, Eugene Yu, David A. Larson and Michael G. Fehlings

Stereotactic body radiotherapy (SBRT) for spinal metastases is an emerging therapeutic option aimed at delivering high biologically effective doses to metastases while sparing the adjacent normal tissues. This technique has emerged following advances in radiation delivery that include sophisticated radiation treatment planning software, body immobilization devices, and capabilities of detecting and correcting patient positional deviations with imageguided radiotherapy. There are limited clinical data specifically supporting the role of SBRT as a superior alternative to conventional radiation in the postoperative patient. The focus of this review was to examine the evidence pertaining to spine SBRT in the treatment of spinal metastases and to provide a comprehensive analysis of published patterns of failure, with emphasis on the postoperative patient.

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Sheeraz Qureshi, Vadim Goz, Steven McAnany, Samuel K. Cho, Andrew C. Hecht, Rick B. Delamarter and Michael G. Fehlings

Object

Cost-effectiveness analysis (CEA) of medical interventions has become increasingly relevant to the discussion of optimization of care. The use of utility scales in CEA permits a quantitative assessment of effectiveness of a given intervention. There are no published utility values for degenerative disc disease (DDD) of the cervical spine, anterior cervical discectomy and fusion (ACDF), or cervical disc replacement (CDR). The purpose of this study was to define health utility values for those health states.

Methods

The 36-Item Short Form Health Survey data from the ProDisc-C investigational device exemption study were obtained for single-level DDD at baseline and 24 months postoperatively after ACDF or CDR procedures. Patients in the original study were randomized to either ACDF or CDR. Utilizing a commercially available Short Form–6 dimensions program, utility scores were calculated for each health state using a set of parametric preference weights obtained from a sample of the general population using the recognized valuation technique of standard gamble.

Results

The baseline health state utility (HSU) value for a patient with single-level DDD was 0.54 in both the ACDF and CDR groups. Postoperative changes in HSU values were seen in both intervention groups at 24 months. Cervical disc replacement had a HSU value of 0.72. Anterior cervical discectomy and fusion was found to have a postoperative utility state of 0.71. No statistically significant difference was found in the HSU for ACDF and CDR at 24 months of follow-up.

Conclusions

This study represents the first calculated HSU value for a patient with single-level cervical DDD. Additionally, 2 common treatment interventions for this disease state were assessed. Both treatments were found to have significant impact on the HSU values. These values are integral to future CEA of ACDF and CDR.

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Diana S. L. Chow, Yang Teng, Elizabeth G. Toups, Bizhan Aarabi, James S. Harrop, Christopher I. Shaffrey, Michele M. Johnson, Maxwell Boakye, Ralph F. Frankowski, Michael G. Fehlings and Robert G. Grossman

Object

The aim of this paper was to characterize individual and population pharmacokinetics of enterally administered riluzole in a Phase 1 clinical trial of riluzole as a neuroprotective agent in adults 18–70 years old with acute spinal cord injury (SCI).

Methods

Thirty-five individuals with acute SCI, American Spinal Injury Association Impairment Scale Grades A–C, neurological levels from C-4 to T-12, who were enrolled in the Phase 1 clinical trial sponsored by the North American Clinical Trials Network for Treatment of Spinal Cord Injury, received 50 mg riluzole twice daily for 28 doses. The first dose was administered at a mean of 8.7 ± 2.2 hours postinjury. Trough plasma samples were collected within 1 hour predose, and peak plasma samples were collected 2 hours postdose on Days 3 and 14 of treatment. Riluzole concentrations were quantified by high-performance liquid chromatography assay. The data were analyzed for individual and population pharmacokinetics using basic structural and covariate models. The pharmacokinetic measures studied were the peak concentration (Cmax), trough concentration (Cmin), systemic exposure (AUC0–12), clearance (CL/F), and volume of distribution (V_F) normalized by the bioavailability (F).

Results

The Cmax and AUC0–12 achieved in SCI patients were lower than those in ALS patients on the same dose basis, due to a higher CL and larger V. The pharmacokinetics of riluzole (Cmax, Cmin, AUC0–12, CL, and V) changed during the acute and subacute phases of SCI during the 14 days of therapy. It was consistently observed in patients at all clinical sites that Cmax, Cmin, and AUC0–12 (128.9 ng/ml, 45.6 ng/ml, and 982.0 ng × hr/ml, respectively) were significantly higher on Day 3 than on Day 14 (76.5 ng/ml, 19.1 ng/ml, and 521.0 ng × hr/ml, respectively). These changes resulted from lower CL (49.5 vs 106.2 L/hour) and smaller V (557.1 vs 1297.9/L) on Day 3. No fluid imbalance or cytochrome P 1A2 induction due to concomitant medications was identified during the treatment course to account for such increases in V and CL, respectively. Possible mechanisms underlying these changes are discussed.

Conclusions

This is the first report of clinical pharmacokinetics of riluzole in patients with SCI. The Cmax and AUC0–12 achieved in SCI patients were lower than those in ALS patients on the same dose basis, due to a higher clearance and larger volume of distribution in SCI patients. The finding in SCI patients of an increase in the clearance and distribution of riluzole between the 3rd and 14th days after SCI, with a lower plasma concentration of riluzole on the 14th day, stresses the importance of monitoring changes in drug metabolism after SCI in interpreting the safety and efficacy of therapeutic drugs that are used in clinical trials in SCI. Clinical trial registration no.: NCT00876889.

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Michael G. Fehlings and Randolph J. Gray

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Editorial

Scarring after spinal cord injury

Michael G. Fehlings and Gregory W. J. Hawryluk

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Editorial

Spinal cord tumor research

Michael G. Fehlings and Soo Yong Chua

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James Guest, James S. Harrop, Bizhan Aarabi, Robert G. Grossman, James W. Fawcett, Michael G. Fehlings and Charles H. Tator

The North American Clinical Trials Network (NACTN) includes 9 clinical centers funded by the US Department of Defense and the Christopher Reeve Paralysis Foundation. Its purpose is to accelerate clinical testing of promising therapeutics in spinal cord injury (SCI) through the development of a robust interactive infrastructure. This structure includes key committees that serve to provide longitudinal guidance to the Network. These committees include the Executive, Data Management, and Neurological Outcome Assessments Committees, and the Therapeutic Selection Committee (TSC), which is the subject of this manuscript. The NACTN brings unique elements to the SCI field. The Network's stability is not restricted to a single clinical trial. Network members have diverse expertise and include experts in clinical care, clinical trial design and methodology, pharmacology, preclinical and clinical research, and advanced rehabilitation techniques. Frequent systematic communication is assigned a high value, as is democratic process, fairness and efficiency of decision making, and resource allocation. This article focuses on how decision making occurs within the TSC to rank alternative therapeutics according to 2 main variables: quality of the preclinical data set, and fit with the Network's aims and capabilities. This selection process is important because if the Network's resources are committed to a therapeutic, alternatives cannot be pursued. A proposed methodology includes a multicriteria decision analysis that uses a Multi-Attribute Global Inference of Quality matrix to quantify the process. To rank therapeutics, the TSC uses a series of consensus steps designed to reduce individual and group bias and limit subjectivity. Given the difficulties encountered by industry in completing clinical trials in SCI, stable collaborative not-for-profit consortia, such as the NACTN, may be essential to clinical progress in SCI. The evolution of the NACTN also offers substantial opportunity to refine decision making and group dynamics. Making the best possible decisions concerning therapeutics selection for trial testing is a cornerstone of the Network's function.