Raja Rampersaud

Early versus Delayed Decompression for Traumatic Cervical Spinal Cord Injury: Results of the Surgical Timing in Acute Spinal Cord Injury Study (STASCIS)

Background There is convincing preclinical evidence that early decompression in the setting of spinal cord injury (SCI) improves neurologic outcomes. However, the effect of early surgical decompression in patients with acute SCI remains uncertain. Our objective was to evaluate the relative effectiveness of early (<24 hours after injury) versus late (≥24 hours after injury) decompressive surgery after traumatic cervical SCI. Methods We performed a multicenter, international, prospective cohort study (Surgical Timing in Acute Spinal Cord Injury Study: STASCIS) in adults aged 16–80 with cervical SCI. Enrolment occurred between 2002 and 2009 at 6 North American centers. The primary outcome was ordinal change in ASIA Impairment Scale (AIS) grade at 6 months follow-up. Secondary outcomes included assessments of complications rates and mortality. Findings A total of 313 patients with acute cervical SCI were enrolled. Of these, 182 underwent early surgery, at a mean of 14.2(±5.4) hours, with the remaining 131 having late surgery, at a mean of 48.3(±29.3) hours. Of the 222 patients with follow-up available at 6 months post injury, 19.8% of patients undergoing early surgery showed a ≥2 grade improvement in AIS compared to 8.8% in the late decompression group (OR = 2.57, 95% CI:1.11,5.97). In the multivariate analysis, adjusted for preoperative neurological status and steroid administration, the odds of at least a 2 grade AIS improvement were 2.8 times higher amongst those who underwent early surgery as compared to those who underwent late surgery (OR = 2.83, 95% CI:1.10,7.28). During the 30 day post injury period, there was 1 mortality in both of the surgical groups. Complications occurred in 24.2% of early surgery patients and 30.5% of late surgery patients (p = 0.21). Conclusion Decompression prior to 24 hours after SCI can be performed safely and is associated with improved neurologic outcome, defined as at least a 2 grade AIS improvement at 6 months follow-up.

Surgical resection of epidural disease improves local control following postoperative spine stereotactic body radiotherapy.

BACKGROUND Spine stereotactic body radiotherapy (SBRT) is increasingly being applied to the postoperative spine metastases patient. Our aim was to identify clinical and dosimetric predictors of local control (LC) and survival. METHODS Eighty patients treated between October 2008 and February 2012 with postoperative SBRT were identified from our prospective database and retrospectively reviewed. RESULTS The median follow-up was 8.3 months. Thirty-five patients (44%) were treated with 18-26 Gy in 1 or 2 fractions, and 45 patients (56%) with 18-40 Gy in 3-5 fractions. Twenty-one local failures (26%) were observed, and the 1-year LC and overall survival (OS) rates were 84% and 64%, respectively. The most common site of failure was within the epidural space (15/21, 71%). Multivariate proportional hazards analysis identified systemic therapy post-SBRT as the only significant predictor of OS (P = .02) and treatment with 18-26 Gy/1 or 2 fractions (P = .02) and a postoperative epidural disease grade of 0 or 1 (0, no epidural disease; 1, epidural disease that compresses dura only, P = .003) as significant predictors of LC. Subset analysis for only those patients (n = 48/80) with high-grade preoperative epidural disease (cord deformed) indicated significantly greater LC rates when surgically downgraded to 0/1 vs 2 (P = .0009). CONCLUSIONS Postoperative SBRT with high total doses ranging from 18 to 26 Gy delivered in 1-2 fractions predicted superior LC, as did postoperative epidural grade.

Biomechanical evaluation of a novel fenestrated pedicle screw augmented with bone cement in osteoporotic spines.

Study Design. Comparative biomechanical study was conducted in osteoporotic human cadaveric spines. Objective. Determine the influence of the volume of polymethyl methacrylate injected through a fenestrated pedicle screw on the pullout strength and on the ability to safely remove the implant. Summary of Background Data. Pedicle screw fixation in the osteoporotic spine can be improved by the addition of bone cement. Various injection techniques have been used. While improvement has been shown for the pullout strength, the optimal volume of cement to inject has not been previously studied. Methods. Seven osteoporotic spines were instrumented with a standard and a fenestrated pedicle screw augmented with polymethyl methacrylate at each level (T7–L5). Three volumes of bone cement were randomly injected and stratified to the thoracic (0.5 cc, 1.0 cc, and 1.5 cc) and lumbar spine (1.5 cc, 2.0 cc, and 2.5 cc). Axial pullout strength and removal torque of the pedicle screws were quantified. Results. The pullout strength of the fenestrated screw was normalized with respect to its contralateral control. Student paired t tests were conducted and a statistically significant increase was noted for 1.0 cc (186 ± 45%) and 1.5 cc (158 ± 46%) in the thoracic spine and for 1.5 cc (264 ± 193%), 2.0 cc (221 ± 93%), and 2.5 cc (198 ± 42%) in the lumbar spine. There was no significant difference with higher volumes of cement. The median removal torque was 0.34 Nm for the standard and 1.83 Nm for the augmented screws. When the augmented implants were removed, the bone cement sheared completely off at the fenestrations in 15 of the 17 cases. Conclusion. Significant increases in pullout strength can be accomplished by injecting a limited quantity of bone cement through a fenestrated screw while minimizing the risks associated with higher volume. The majority of implants were removed without damaging the vertebra as the bone cement sheared off at the fenestrations.

Clinical Accuracy of Computer-Assisted Two-Dimensional Fluoroscopy for the Percutaneous Placement of Lumbosacral Pedicle Screws

Study Design. Clinical case series. Objective. The primary objective of this study was to evaluate the clinical accuracy of computer-assisted two-dimensional fluoroscopy (2D-CAS) for the percutaneous placement of lumbosacral pedicle screws. Summary of Background Data. Loss of visual anatomic landmarks and reduced tactile feedback increases the risk of pedicle screw misplacement by when using minimally invasive (MIS) percutaneous techniques. However, objective data on screw misplacement in this scenario is lacking. Methods. A MIS-2D-CAS technique (FluoroNav) was used for the placement of pedicle screws in 41 consecutive patients undergoing MIS—interbody instrumented fusion. Postoperative computerized tomography (CT) was obtained in all patients at 6 months after surgery and was evaluated by 3 observers. The relative position of the screw to the pedicle was graded regarding pedicle breach (I, no breach; II, <2 mm; III, 2–4 mm; IV, >4 mm), breach direction, vertebral body perforation and screw trajectory. Interobserver reliability of CT grading was assessed with kappa statistics. Results. A total of 161 screws were placed. No neurologic, vascular, or visceral injuries occurred. About 37 (23%) screws breached the pedicle. The majority (83.8%, 31/37) of breaches were graded II. There were 5 Grade III and 1 Grade IV breaches. Medial versus lateral breaches occurred in 30% (11/37) and 60% (22/37), respectively; 10% (4/37) of the breaches were superior. Overall, 8 (5%) vertebral body breaches occurred. Of the pedicle screws, 19 (12%) had trajectories that deviated from acceptable, with the majority being medial (16/19, 84%). Fluoroscopy time for screw placement was typically less than 20 seconds total per case. There was 1 clinically significant breach at L5 (III, medial) which resulted in a L5 radiculopathy. Kappa statistics showed excellent overall agreement between reviewers (k = 0.73–0.92; 90%–96% agreement). Conclusion. The two-dimensional (2D) virtual fluoroscopy is a clinically acceptable option for percutaneous placement of pedicle screws. However, this technique requires cautious application and is particularly vulnerable to axial trajectory errors.

Technique for stereotactic body radiotherapy for spinal metastases

Stereotactic body radiotherapy (SBRT) is an emerging technique for spinal tumours that is a natural succession to brain radiosurgery. The spine is an ideal site for SBRT due to its relative immobility and the potential clinical benefits of high dose delivery, particularly to optimise local control and avoid disease progression that can result in spinal cord compression. However, the proximity of the tumour to the spinal cord, with the potential for radiation myelopathy if the dose is delivered inaccurately or if the spinal cord dose limit is set too high, demands technical accuracy with radiation myelopathy a feared complication. Spine SBRT has been delivered with either a robotic-based linac system such as the Cyberknife, or with linac-based systems equipped with a multileaf collimator and image guidance system. Regardless of the technology, spine SBRT demands sophisticated treatment planning and delivery. This case-based technical review outlines the SBRT apparatus, planning and treatment delivery in use at the University of Toronto, Toronto, Canada.

Interobserver and Intraobserver Reliability of Maximum Canal Compromise and Spinal Cord Compression for Evaluation of Acute Traumatic Cervical Spinal Cord Injury

Study Design. Prospective, blinded validation study of an objective, quantitative measure to assess maximum canal compromise (MCC) and maximum spinal cord compression (MSCC) in individuals with acute cervical spinal cord injury (SCI). Objective. To examine the intraobserver and interobserver reliability of MCC and MSCC in individuals with acute traumatic cervical SCI. Summary of Background Data. To date, few quantitative reliable radiologic methods for assessing the extent of spinal cord compression in the setting of acute SCI have been reported. MCC and MSCC, as assessed on mid-sagittal CT and T2-weighted MR images, respectively, appear to have potential clinical and prognostic value. To date, the validation of these assessment tools has been limited to a small number of observers at a single institution. However, to date no study has focused on the reliability of these radiologic parameters among a large cohort of spine surgeons from North America and abroad. This type of validation is critical to allow the broader use of these outcome measures in research studies and in clinical practice. Methods. Mid-sagittal MRI and CT images of cervical spine were selected from 10 individuals with acute traumatic cervical SCI. A total of 28 spine surgeons independently estimated CT MCC, T1-weighted MRI MCC, and T2-weighted MRI MSCC on two occasions using a calibrated ruler. In the first round of measurements, the observers estimated the radiologic parameters using only written instructions. The second measurement set was obtained after an interactive teaching session on the methodology. The order of the images was altered for the second set of measurements. Results. Analysis using parametric and nonparametric statistics indicated high intraobserver reliability for CT MCC, T1-weighted MRI MCC, and T2-weighted MSCC with interclass correlation coefficients (ICCs) of 0.92, 0.95, and 0.97, respectively. The interobserver reliability for all three radiologic parameters was considered moderate with ICCs ranging from 0.35 to 0.56. Conclusion. Our results indicate that the intraobserver reliability for the MCC and MSCC was high. Although the interobserver reliability for all three radiologic parameters in the present study was below 0.75, the observed differences were small and largely accounted for by the limitations in the precision of the calibrated ruler. For cases with minimal cord compression, the measurement of canal stenosis (MCC) proved more accurate. In contrast, in cases with severe cord compression, the assessment of MSCC was more accurate. It is anticipated that the use of digital imaging technologies will further enhance the precision of these outcome measures.

Variations in surgical treatment of cervical facet dislocations.

Study Design. Retrospective Survey Analysis. Objective. To explore surgeon preference in the choice of surgical approach in the treatment of traumatic cervical facet dislocations. Summary of Background Data. The choice of surgical approach in the treatment of traumatic cervical dislocations is highly variable and maybe influenced by a variety of factors. The purpose of this study was to examine inter-rater reliability in choice of surgical approach. Methods. Twenty-five members of the Spine Trauma Study Group evaluated 10 cases of traumatic cervical dislocations. Evaluation of the case as a unilateral or bilateral injury and surgeon interpretation of the presence of a disc herniation as well as preferred surgical approach were assessed. Results. Only slight agreement was observed among surgeons in the choice of surgical approach (Kappa < 0.1). This improved slightly when patients were assumed to have a complete spinal cord injury (Kappa = 0.15). Surgeons used more anterior approaches either alone or as the first stage in a combined approach when a disc herniation was present regardless of neurologic status of the patient. When a patient was neurologically intact, an anterior approach was more common than a posterior approach even when a disc herniation was not present. Combined approaches were preferred for the treatment of bilateral facet dislocations. Conclusion. The poor agreement on the treatment of these injuries likely reflects a combination of factors including surgeon training and experience. Treatment decisions are likely to be affected by the neurologic status of the patient, interpretation of a disc herniation, and the classification of the injury as a unilateral or bilateral injury.

Predicting SF-6D utility scores from the Oswestry Disability Index and Numeric Rating Scales for Back and Leg Pain

Study Design. Cross-sectional cohort. Objective. The purpose of this study is to provide a model to allow estimation of utility from the Short Form (SF)-6D using data from the Oswestry Disability Index (ODI), Back Pain Numeric Rating Scale (BPNRS), and the Leg Pain Numeric Rating Scale (LPNRS). Summary of Background Data. Cost-utility analysis provides important information about the relative value of interventions and requires a measure of utility not often available from clinical trial data. The ODI and numeric rating scales for back (BPNRS) and leg pain (LPNRS), are widely used disease-specific measures for health-related quality of life in patients with lumbar degenerative disorders. The purpose of this study is to provide a model to allow estimation of utility from the SF-6D using data from the ODI, BPNRS, and the LPNRS. Methods. SF-36, ODI, BPNRS, and LPNRS were prospectively collected before surgery, at 12 and 24 months after surgery in 2640 patients undergoing lumbar fusion for degenerative disorders. Spearman correlation coefficients for paired observations from multiple time points between ODI, BPNRS, and LPNRS, and SF-6D utility scores were determined. Regression modeling was done to compute the SF-6D score from the ODI, BPNRS, and LPNRS. Using a separate, independent dataset of 2174 patients in which actual SF-6D and ODI scores were available, the SF-6D was estimated for each subject and compared to their actual SF-6D. Results. In the development sample, the mean age was 52.5 ± 15 years and 34% were male. In the validation sample, the mean age was 52.9 ± 14.2 years and 44% were male. Correlations between the SF-6D and the ODI, BPNRS, and LPNRS were statistically significant (P < 0.0001) with correlation coefficients of 0.82, 0.78, and 0.72, respectively. The regression equation using ODI, BPNRS,and LPNRS to predict SF-6D had an R2 of 0.69 and a root mean square error of 0.076. The model using ODI alone had an R2 of 0.67 and a root mean square error of 0.078. The correlation coefficient between the observed and estimated SF-6D score was 0.80. In the validation analysis, there was no statistically significant difference (P = 0.11) between actual mean SF-6D (0.55 ± 0.12) and the estimated mean SF-6D score (0.55 ± 0.10) using the ODI regression model. Conclusion. This regression-based algorithm may be used to predict SF-6D scores in studies of lumbar degenerative disease that have collected ODI but not utility scores.

Predictors of complications after spinal stabilization of thoracolumbar spine injuries.

BACKGROUND The management of complications after major traumatic spinal injury and surgical stabilization is a challenge. The purpose of this study is to identify factors predictive of a complication after surgical stabilization of thoracolumbar spine injuries. METHODS A review of subjects prospectively enrolled in a multicenter database for spine trauma was performed. Standard demographic data, Glasgow Coma Scores, Injury Severity Score, American Spinal Injury Association score, Charlson Comorbiditiy Index (CCI), mechanism of injury, administration of methylprednisolone (National Acute Spinal Cord Injury II, III), time from injury to surgery, and surgical approach were evaluated. All perioperative complications within 6 months of surgery were recorded. Multivariate logistic regression analysis was performed to identify factors predictive of the occurrence of a complication after surgical stabilization of a thoracolumbar injury. RESULTS There were 230 patients (57 women, 173 men), 35% were smokers. The mean age at injury was 41.8 ± 17.8 years. The majority of patients (52%) had no neurologic deficits. Nineteen percent had complete cord injuries whereas 29% had incomplete cord injuries. The mean admission ISS was 9.2 ± 7.8, mean CCI was 0.2 ± 0.7, mean Glasgow Coma Score was 14.6 ± 1.6. NASCIS II and III was instituted in 15.5% and 4.2% of all patients, respectively; mean time from injury to surgery was 8.9 ± 59 days. The incidence of complications was 79% (minor 30%, major 49%). No factors predictive of a minor complication were identified. Factors predictive of the occurrence of a major complication were administration of high-dose steroids, ASIA score, and CCI. CONCLUSION The severity of neurologic injury, number of comorbidities, and use of the high-dose steroids independently increase the risk of having a major complication after surgical stabilization of thoracolumbar spine fractures.

Surgical treatment of unstable type II odontoid fractures in skeletally mature individuals.

Study Design. Systematic review of literature. Objective. To determine the optimal indications and methods of surgical treatment for unstable type II odontoid fractures in skeletally mature individuals. Summary of Background Data. Odontoid fractures are a frequently encountered injury pattern in the cervical spine. The surgical treatment of type II odontoid fractures varies among spinal surgeons. The optimal surgical indications and treatment for type II odontoid fractures remains unclear. Methods. Five primary research questions, based on safety and efficacy, were determined by consensus of a panel of spine trauma surgeons consisting of fellowship trained orthopedic and neurologic surgeons. A comprehensive review of the literature was performed using MeSH search terms in MEDLINE, PubMed, EMBASE, CINAHL, and the Cochrane Database of Systematic reviews. The quality of literature was rated as high, moderate, low, or very low. Using the GRADE evidence-based review system, the primary questions were answered using the literature review and expert opinion. These treatment recommendations were then rated as either strong or weak based on the quality of evidence and clinical expertise. Results. The initial search resulted in over 1300 results. After initial application of all inclusion and exclusion criteria, 458 abstracts were reviewed from which 22 manuscripts were found to meet all criteria. These were obtained, reviewed, and used to create an evidentiary table. All articles were of either low or very low quality. Conclusion. There is no moderate or high quality literature on the surgical management of acute type II odontoid fractures. Optimal indications for either anterior or posterior treatment of fractures are described but with no comparative data. A single anterior odontoid screw is the recommended technique for anterior treatment. Posterior internal fixation (C1–C2 transarticular screw, C1–C2 segmental fixation) is the recommended technique for posterior treatment. In equivocally indicated instances, anterior or posterior treatment can be safely used with good outcome. In this scenario, surgical management decision should be influenced by surgeon and patient preference as well as cost considerations.