A Clinical Practice Guideline for the Management of Patients With Acute Spinal Cord Injury: Recommendations on the Use of Methylprednisolone Sodium Succinate

INTRODUCTION

The objective of this guideline is to outline the appropriate use of methylprednisolone sodium succinate (MPSS) in patients with acute spinal cord injury (SCI).

METHODS

A systematic review of the literature was conducted to address key questions related to the use of MPSS in acute SCI. A multidisciplinary Guideline Development Group used this information, in combination with their clinical expertise, to develop recommendations for the use of MPSS. Based on GRADE (Grading of Recommendation, Assessment, Development and Evaluation), a strong recommendation is worded as "we recommend," whereas a weaker recommendation is indicated by "we suggest."

RESULTS

The main conclusions from the systematic review included the following: (1) there were no differences in motor score change at any time point in patients treated with MPSS compared to those not receiving steroids; (2) when MPSS was administered within 8 hours of injury, pooled results at 6- and 12-months indicated modest improvements in mean motor scores in the MPSS group compared with the control group; and (3) there was no statistical difference between treatment groups in the risk of complications. Our recommendations were: (1) "We suggest not offering a 24-hour infusion of high-dose MPSS to adult patients who present after 8 hours with acute SCI"; (2) "We suggest a 24-hour infusion of high-dose MPSS be offered to adult patients within 8 hours of acute SCI as a treatment option"; and (3) "We suggest not offering a 48-hour infusion of high-dose MPSS to adult patients with acute SCI."

CONCLUSIONS

These guidelines should be implemented into clinical practice to improve outcomes and reduce morbidity in SCI patients.

A Clinical Practice Guideline for the Management of Patients With Acute Spinal Cord Injury: Recommendations on the Role of Baseline Magnetic Resonance Imaging in Clinical Decision Making and Outcome Prediction

INTRODUCTION

The objective of this guideline is to outline the role of magnetic resonance imaging (MRI) in clinical decision making and outcome prediction in patients with traumatic spinal cord injury (SCI).

METHODS

A systematic review of the literature was conducted to address key questions related to the use of MRI in patients with traumatic SCI. This review focused on longitudinal studies that controlled for baseline neurologic status. A multidisciplinary Guideline Development Group (GDG) used this information, their clinical expertise, and patient input to develop recommendations on the use of MRI for SCI patients. Based on GRADE (Grading of Recommendation, Assessment, Development and Evaluation), a strong recommendation is worded as "we recommend," whereas a weaker recommendation is indicated by "we suggest."

RESULTS

Based on the limited available evidence and the clinical expertise of the GDG, our recommendations were: (1) "We suggest that MRI be performed in adult patients with acute SCI prior to surgical intervention, when feasible, to facilitate improved clinical decision-making" (quality of evidence, very low) and (2) "We suggest that MRI should be performed in adult patients in the acute period following SCI, before or after surgical intervention, to improve prediction of neurologic outcome" (quality of evidence, low).

CONCLUSIONS

These guidelines should be implemented into clinical practice to improve outcomes and prognostication for patients with SCI.

Effect of older age on treatment decisions and outcomes among patients with traumatic spinal cord injury

BACKGROUND

Older people are at increased risk of traumatic spinal cord injury from falls. We evaluated the impact of older age (≥ 70 yr) on treatment decisions and outcomes.

METHODS

We identified patients with traumatic spinal cord injury for whom consent and detailed data were available from among patients recruited (2004-2013) at any of the 31 acute care and rehabilitation hospitals participating in the Rick Hansen Spinal Cord Injury Registry. Patients were assessed by age group (< 70 v. ≥ 70 yr). The primary outcome was the rate of acute surgical treatment. We used bivariate and multivariate regression models to assess patient and injury-related factors associated with receiving surgical treatment and with the timing of surgery after arrival to a participating centre.

RESULTS

Of the 1440 patients included in our study cohort, 167 (11.6%) were 70 years or older at the time of injury. Older patients were more likely than younger patients to be injured by falling (83.1% v. 37.4%; p < 0.001), to have a cervical injury (78.0% v. 61.6%; p = 0.001), to have less severe injuries on admission (American Spinal Injury Association Impairment Scale grade C or D: 70.5% v. 46.9%; p < 0.001), to have a longer stay in an acute care hospital (median 35 v. 28 d; p < 0.005) and to have a higher in-hospital mortality (4.2% v. 0.6%; p < 0.001). Multivariate analysis did not show that age of 70 years or more at injury was associated with a decreased likelihood of surgical treatment (adjusted odds ratio [OR] 0.48, 95% confidence interval [CI] 0.22-1.07). An unplanned sensitivity analysis with different age thresholds showed that a threshold of 65 years was associated with a decreased chance of surgical treatment (OR 0.39, 95% CI 0.19-0.80). Older patients who underwent surgical treatment had a significantly longer wait time from admission to surgery than younger patients (37 v. 19 h; p < 0.001).

INTERPRETATION

We found chronological age to be a factor influencing treatment decisions but not at the 70-year age threshold that we had hypothesized. Older patients waited longer for surgery and had a substantially higher in-hospital mortality despite having less severe injuries than younger patients. Further research into the link between treatment delays and outcomes among older patients could inform surgical guideline development.

Metastatic renal cell carcinoma mimicking a schwannoma in a dorsal root ganglion: case report

Peripheral nerve tumors are soft-tissue tumors that can occur in any nerve throughout the body. The majority of peripheral nerve tumors arise from elements of the nerve sheath with the two most common being neurofibromas and schwannomas. More than 90% of all peripheral nerve tumors are benign. When there is peripheral nerve involvement in metastatic carcinoma, it is often via contiguous spread from the primary mass; hematogenous seeding to a peripheral nerve is seldom seen. In this report the authors describe the even rarer case of metastatic renal cell carcinoma mimicking a schwannoma in a dorsal root ganglion. Cases from the literature show the rarity of this finding and its late clinical appearance. Given that survival in patients with metastatic carcinoma continues to increase, dorsal root ganglion metastasis may become more common over time.

The influence of time from injury to surgery on motor recovery and length of hospital stay in acute traumatic spinal cord injury: an observational Canadian cohort study

To determine the influence of time from injury to surgery on neurological recovery and length of stay (LOS) in an observational cohort of individuals with traumatic spinal cord injury (tSCI), we analyzed the baseline and follow-up motor scores of participants in the Rick Hansen Spinal Cord Injury Registry to specifically assess the effect of an early (less than 24 h from injury) surgical procedure on motor recovery and on LOS. One thousand four hundred and ten patients who sustained acute tSCIs with baseline American Spinal Injury Association Impairment Scale (AIS) grades A, B, C, or D and were treated surgically were analyzed to determine the effect of the timing of surgery (24, 48, or 72 h from injury) on motor recovery and LOS. Depending on the distribution of data, we used different types of generalized linear models, including multiple linear regression, gamma regression, and negative binomial regression. Persons with incomplete AIS B, C, and D injuries from C2 to L2 demonstrated motor recovery improvement of an additional 6.3 motor points (SE=2.8 p<0.03) when they underwent surgical treatment within 24 h from the time of injury, compared with those who had surgery later than 24 h post-injury. This beneficial effect of early surgery on motor recovery was not seen in the patients with AIS A complete SCI. AIS A and B patients who received early surgery experienced shorter hospital LOS. While the issues of when to perform surgery and what specific operation to perform remain controversial, this work provides evidence that for an incomplete acute tSCI in the cervical, thoracic, or thoracolumbar spine, surgery performed within 24 h from injury improves motor neurological recovery. Early surgery also reduces LOS.

Low birth weight is associated with adiposity, impaired skeletal muscle energetics and weight loss resistance in mice

BACKGROUND

In utero undernutrition is associated with obesity and insulin resistance, although its effects on skeletal muscle remain poorly defined. Therefore, in the current study we explored the effects of in utero food restriction on muscle energy metabolism in mice.

METHODS

We used an experimental mouse model system of maternal undernutrition during late pregnancy to examine offspring from undernourished dams (U) and control offspring from ad libitum-fed dams (C). Weight loss of 10-week-old offspring on a 4-week 40% calorie-restricted diet was also followed. Experimental approaches included bioenergetic analyses in isolated mitochondria, intact (permeabilized) muscle and at the whole body level.

RESULTS

U have increased adiposity and decreased glucose tolerance compared to C. Strikingly, when U are put on a 40% calorie-restricted diet they lose half as much weight as calorie-restricted controls. Mitochondria from muscle overall from U had decreased coupled (state 3) and uncoupled (state 4) respiration and increased maximal respiration compared to C. Mitochondrial yield was lower in U than C. In permeabilized fiber preparations from mixed fiber-type muscle, U had decreased mitochondrial content and decreased adenylate-free leak respiration, fatty acid oxidative capacity and state 3 respiratory capacity through complex I. Fiber maximal oxidative phosphorylation capacity did not differ between U and C but was decreased with calorie restriction.

CONCLUSIONS

Our results reveal that in utero undernutrition alters metabolic physiology through a profound effect on skeletal muscle energetics and blunts response to a hypocaloric diet in adulthood. We propose that mitochondrial dysfunction links undernutrition in utero with metabolic disease in adulthood.

Minimizing errors in acute traumatic spinal cord injury trials by acknowledging the heterogeneity of spinal cord anatomy and injury severity: an observational Canadian cohort analysis

Clinical trials of therapies for acute traumatic spinal cord injury (tSCI) have failed to convincingly demonstrate efficacy in improving neurologic function. Failing to acknowledge the heterogeneity of these injuries and under-appreciating the impact of the most important baseline prognostic variables likely contributes to this translational failure. Our hypothesis was that neurological level and severity of initial injury (measured by the American Spinal Injury Association Impairment Scale [AIS]) act jointly and are the major determinants of motor recovery. Our objective was to quantify the influence of these variables when considered together on early motor score recovery following acute tSCI. Eight hundred thirty-six participants from the Rick Hansen Spinal Cord Injury Registry were analyzed for motor score improvement from baseline to follow-up. In AIS A, B, and C patients, cervical and thoracic injuries displayed significantly different motor score recovery. AIS A patients with thoracic (T2-T10) and thoracolumbar (T11-L2) injuries had significantly different motor improvement. High (C1-C4) and low (C5-T1) cervical injuries demonstrated differences in upper extremity motor recovery in AIS B, C, and D. A hypothetical clinical trial example demonstrated the benefits of stratifying on neurological level and severity of injury. Clinically meaningful motor score recovery is predictably related to the neurological level of injury and the severity of the baseline neurological impairment. Stratifying clinical trial cohorts using a joint distribution of these two variables will enhance a study's chance of identifying a true treatment effect and minimize the risk of misattributed treatment effects. Clinical studies should stratify participants based on these factors and record the number of participants and their mean baseline motor scores for each category of this joint distribution as part of the reporting of participant characteristics. Improved clinical trial design is a high priority as new therapies and interventions for tSCI emerge.

Meeting the privacy requirements for the development of a multi-centre patient registry in Canada: the Rick Hansen Spinal Cord Injury Registry

Privacy legislation addresses concerns regarding the privacy of personal information; however, its interpretation by research ethics boards has resulted in significant challenges to the collection, management, use and disclosure of personal health information for multi-centre research studies. This paper describes the strategy used to develop the national Rick Hansen Spinal Cord Injury Registry (RHSCIR) in accordance with privacy statutes and benchmarked against best practices. An analysis of the regional and national privacy legislation was conducted to determine the requirements for each of the 31 local RHSCIR sites and the national RHSCIR office. A national privacy and security framework was created for RHSCIR that includes a governance structure, standard operating procedures, training processes, physical and technical security and privacy impact assessments. The framework meets a high-water mark in ensuring privacy and security of personal health information nationally and may assist in the development of other national or international research initiatives.

Target binding improves relaxivity in aptamer-gadolinium conjugates

MRI contrast agents (CA) have been heavily used over the past several decades to enhance the diagnostic value of the obtained images. From a design perspective, two avenues to improve the efficacy of contrast agents are readily evident: optimization of magnetic properties of the CA, and optimization of the pharmacokinetics and distribution of the CA in the patient. Contrast agents consisting of DNA aptamer-gadolinium(III) conjugates provide a single system in which these factors can be addressed simultaneously. In this proof-of-concept study, the 15mer thrombin aptamer was conjugated to diethylenetriaminepentaacetic (DTPA) dianhydride to form a monoamide derivative of the linear open-chain chelate present in the commonly used contrast agent Magnevist(®). The stability of the conjugated DNA aptamer-DTPA-Gd(III) chelate in a transmetallation study using Zn(II) was found to be similar to that reported for DTPA-Gd(III). Relaxivity enhancements of 35 ± 4 and 20 ± 1 % were observed in the presence of thrombin compared to a control protein at fields of 9.4 and 1.5 T, respectively. The inclusion of spacers between the aptamer and the DTPA to eliminate possible steric effects was also investigated but not found to improve the relaxation enhancement achieved in comparison to the unaltered aptamer conjugate.

Ablation of LMO4 in glutamatergic neurons impairs leptin control of fat metabolism

The LIM domain only 4 (LMO4) protein is expressed in the hypothalamus, but its function there is not known. Using mice with LMO4 ablated in postnatal glutamatergic neurons, including most neurons of the paraventricular (PVN) and ventromedial (VMH) hypothalamic nuclei where LMO4 is expressed, we asked whether LMO4 is required for metabolic homeostasis. LMO4 mutant mice exhibited early onset adiposity. These mice had reduced energy expenditure and impaired thermogenesis together with reduced sympathetic outflow to adipose tissues. The peptide hormone leptin, produced from adipocytes, activates Jak/Stat3 signaling at the hypothalamus to control food intake, energy expenditure, and fat metabolism. Intracerebroventricular infusion of leptin suppressed feeding similarly in LMO4 mutant and control mice. However, leptin-induced fat loss was impaired and activation of Stat3 in the VMH was blunted in these mice. Thus, our study identifies LMO4 as a novel modulator of leptin function in selective hypothalamic nuclei to regulate fat metabolism.

Daily smoking and lower back pain in adult Canadians: the Canadian Community Health Survey

Background:

Lower back pain (LBP) is one of the primary causes of disability in the Canadian community. However, only a limited number of studies have addressed the association between daily smoking and LBP in Canada. Of the studies that have explored this association, many had small sample sizes and failed to control for confounders.

Objective:

The primary objective of the study was to determine if daily smoking is associated with an increased risk of having LBP. The secondary objectives were to assess the risk for LBP among occasional smokers and to determine the prevalence of LBP in relation to different covariates.

Data and study design:

Using the Canadian Community Health Survey (cycle 3.1) data, 73,507 Canadians between the ages of 20 and 59 years were identified. LBP status, smoking level, sex, age, body mass index (BMI), level of activity and level of education were assessed in these subjects.

Methods:

Stratified analysis and logistic regression analysis were used to detect effect modifications and to adjust for covariates. Population weight and design were taken into consideration.

Results:

The prevalence of LBP was 23.3% among daily smokers and 15.7% among non-smokers. Age and sex were found to be effect modifiers. The association between LBP and daily smoking was statistically significant in all ages and genders; this association was stronger for younger age groups. The adjusted odds ratio for male daily smokers aged 20 to 29 was 1.87 (95% CI = 1.62, 2.17); findings were similar for women. Occasional smoking slightly increased the odds of having back pain.

Conclusion:

Young Canadian daily smokers are at higher risk for LBP. This study also suggests a positive correlation between smoking dose and the risk of LBP. These findings indicate that smoking behavioral modification may have an impact on reducing back pain especially among young adults.

Electrospun Biocomposite Polycaprolactone/Collagen Tubes as Scaffolds for Neural Stem Cell Differentiation

Studies using cellular therapies, scaffolds, and tubular structured implants have been carried out with the goal to restore functional recovery after spinal cord injury (SCI). None of these therapeutic strategies, by themselves, have been shown to be sufficient to achieve complete restoration of function. To reverse the devastating effects of SCI, an interdisciplinary approach that combines materials science and engineering, stem cell biology, and neurosurgery is being carried out. We are currently investigating a scaffold that has the ability to deliver growth factors for the proliferation and differentiation of endogenous stem cells. Neural stem cells (NSCs) derived from mice are being used to assess the efficacy of the release of growth factors from the scaffold in vitro. The fabrication of the tubular implant allows a porous scaffold to be formed, which aids in the release of growth factors added to the scaffold.

A systematic review of cellular transplantation therapies for spinal cord injury

Cell transplantation therapies have become a major focus in pre-clinical research as a promising strategy for the treatment of spinal cord injury (SCI). In this article, we systematically review the available pre-clinical literature on the most commonly used cell types in order to assess the body of evidence that may support their translation to human SCI patients. These cell types include Schwann cells, olfactory ensheathing glial cells, embryonic and adult neural stem/progenitor cells, fate-restricted neural/glial precursor cells, and bone-marrow stromal cells. Studies were included for review only if they described the transplantation of the cell substrate into an in-vivo model of traumatic SCI, induced either bluntly or sharply. Using these inclusion criteria, 162 studies were identified and reviewed in detail, emphasizing their behavioral effects (although not limiting the scope of the discussion to behavioral effects alone). Significant differences between cells of the same "type" exist based on the species and age of donor, as well as culture conditions and mode of delivery. Many of these studies used cell transplantations in combination with other strategies. The systematic review makes it very apparent that cells derived from rodent sources have been the most extensively studied, while only 19 studies reported the transplantation of human cells, nine of which utilized bone-marrow stromal cells. Similarly, the vast majority of studies have been conducted in rodent models of injury, and few studies have investigated cell transplantation in larger mammals or primates. With respect to the timing of intervention, nearly all of the studies reviewed were conducted with transplantations occurring subacutely and acutely, while chronic treatments were rare and often failed to yield functional benefits.

Nonseminomatous germ cell tumor after chemotherapy with residual mass invading the spine

Bony metastasis is a rare feature of metastatic nonseminomatous germ cell tumor. A 25 year-old man presented with back pain radiating down both legs, and a subsequent work-up demonstrated a right-sided testicular mass with bilateral retroperitoneal lymphadenopathy and tumor involvement of the L2 vertebra. Radical inguinal orchiectomy confirmed nonseminomatous germ cell tumor, and the patient underwent chemotherapy with a residual mass and vertebral involvement by MRI. Combined vertebral resection with spinal reconstruction and retroperitoneal lymph node dissection demonstrated residual fibrosis. While bony metastasis of nonseminomatous germ cell tumors is rare, resection with spinal reconstruction can be accomplished with acceptable morbidity.

Matrix inclusion within synthetic hydrogel guidance channels improves specific supraspinal and local axonal regeneration after complete spinal cord transection

We have previously shown that a novel synthetic hydrogel channel composed of poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (pHEMA-MMA) is biocompatible and supports axonal regeneration after spinal cord injury. Our goal was to improve the number and type of regenerated axons within the spinal cord through the addition of different matrices and growth factors incorporated within the lumen of the channel. After complete spinal cord transection at T8, pHEMA-MMA channels, having an elastic modulus of 263+/-13 kPa were implanted into adult Sprague Dawley rats. The channels were then filled with one of the following matrices: collagen, fibrin, Matrigel, methylcellulose, or smaller pHEMA-MMA tubes placed within a larger pHEMA-MMA channel (called tubes within channels, TWC). We also supplemented selected matrices (collagen and fibrin) with neurotrophic factors, fibroblast growth factor-1 (FGF-1) and neurotrophin-3 (NT-3). After channel implantation, fibrin glue was applied to the cord-channel interface, and a duraplasty was performed with an expanded polytetrafluoroethylene (ePTFE) membrane. Controls included animals that had either complete spinal cord transection and implantation of unfilled pHEMA-MMA channels or complete spinal cord transection. Regeneration was assessed by retrograde axonal tracing with Fluoro-Gold, and immunohistochemistry with NF-200 (for total axon counts) and calcitonin gene related peptide (CGRP, for sensory axon counts) after 8 weeks survival. Fibrin, Matrigel, methylcellulose, collagen with FGF-1, collagen with NT-3, fibrin with FGF-1, and fibrin with NT-3 increased the total axon density within the channel (ANOVA, p<0.05) compared to unfilled channel controls. Only fibrin with FGF-1 decreased the sensory axon density compared to unfilled channel controls (ANOVA, p<0.05). Fibrin promoted the greatest axonal regeneration from reticular neurons, and methylcellulose promoted the greatest regeneration from vestibular and red nucleus neurons. With Matrigel, there was no axonal regeneration from brainstem motor neurons. The addition of FGF-1 increased the axonal regeneration of vestibular neurons, and the addition of NT-3 decreased the total number of axons regenerating from brainstem neurons. The fibrin and TWC showed a consistent improvement in locomotor function at both 7 and 8 weeks. Thus, the present study shows that the presence and type of matrix contained within synthetic hydrogel guidance channels affects the quantity and origin of axons that regenerate after complete spinal cord transection, and can improve functional recovery. Determining the optimum matrices and growth factors for insertion into these guidance channels will improve regeneration of the injured spinal cord.

Neuroprotection and regeneration strategies for spinal cord repair

The journey toward a cure for spinal cord injury (SCI) has taken many paths. In this article, we review these paths, and highlight the clinical applications of these experimental repair strategies. Initial strategies involved attempts at neuroprotection with steroids and other anti-inflammatory drugs. Other anti-ischemia treatments, agents to eliminate the damage from excitotoxicity, and anti-apoptotic agents were also tried. Another avenue involved enhancing the function of the remaining uninjured axons by measures to produce remyelination and medications to improve axonal conduction. In the last two decades there has been a major effort to enhance spinal cord axonal regeneration through a variety of techniques including neutralization of neurite inhibition, administration of neurotrophic factors, implantation of synthetic channels, and transplantation of a variety of cell types. Indeed, several of these strategies have been so promising in animals that clinicians have been stimulated to explore their potential human application. We also examine the different experimental models of SCI used to assess repair, and discuss how the injury model impacts on the assessment of axonal regeneration and functional recovery after SCI. The mechanisms of recovery that may be involved after SCI will be analyzed, and their relevance toward finding a cure for human SCI. Unfortunately, the goal of producing significant functional regeneration of the human spinal cord has not yet been achieved despite the many strategies that have been developed. It is our hope that improved understanding of the mechanisms underlying functional recovery will lead to successful therapeutic strategies in humans.

Corticospinal regeneration into lumbar grey matter correlates with locomotor recovery after complete spinal cord transection and repair with peripheral nerve grafts, fibroblast growth factor 1, fibrin glue, and spinal fusion

Knowledge of which tracts are essential for the recovery of locomotor function in rats after repair is unknown. To assess the mechanism of recovery, we examined the correlation between functional recovery and axonal regeneration. All rats underwent complete cord transection and repair with peripheral nerves, fibroblast growth factor 1, fibrin glue, and spinal fixation. Repaired rats recovered both motor-evoked potentials recorded at the lumbar level and locomotor function. Cord retransection rostral to the repair abolished the recovery, indicating improvement was due to long tract regeneration. To determine which long tracts correlated with recovery, a novel technique of simultaneous bidirectional axonal tracing and immunohistochemical examination of axonal type was used to quantitate the regeneration of corticospinal, rubrospinal, reticulospinal, vestibulospinal, raphespinal, propriospinal, serotonergic, and calcitonin gene-related peptide containing axons. Multiple linear regression analysis revealed recovery of function correlated only with regeneration of corticospinal axons into the gray matter of the lumbar spinal cord (R = 0.977, p < 0.02). For the first time, we show that regeneration of the corticospinal tract into the lumbar gray matter is a mechanism of functional locomotor recovery after complete cord transection and repair.

Synthetic hydrogel guidance channels facilitate regeneration of adult rat brainstem motor axons after complete spinal cord transection

Synthetic guidance channels or tubes have been shown to promote axonal regeneration within the spinal cord from brainstem motor nuclei with the inclusion of agents such as matrices, cells, or growth factors to the tube. We examined the biocompatibility and regenerative capacity of synthetic hydrogel tubular devices that were composed of poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (PHEMA-MMA). Two PHEMA-MMA channels, having a mean elastic modulus of either 177 or 311 kPa were implanted into T8-transected spinal cords of adult Sprague Dawley rats. The cord stumps were inserted into the channels and fibrin glue was applied to the cord-channel interface. An expanded polytetrafluoroethylene (ePTFE) membrane was used for duraplasty. Controls underwent cord transection alone. Gross and microscopic examination of the spinal cords showed continuity of tissue within the synthetic guidance channels between the cord stumps at 4 and 8 weeks. There was a trend towards an increased area and width of bridging neural tissue in the 311-kPa guidance channels compared to the 177-kPa channels. Neurofilament stained axons were visualized within the bridging tissue, and serotonergic axons were found to enter the 311-kPa channel. Retrograde axonal tracing revealed regeneration of axons from reticular, vestibular, and raphe brainstem motor nuclei. For both channels, there was minimal scarring at the channel-cord interface, and less scarring at the channel-dura interface compared to that observed next to the ePTFE. The present study is the first to show that axons from brainstem motor nuclei regenerated in unfilled synthetic hydrogel guidance channels after complete spinal cord transection.

Novel intrathecal delivery system for treatment of spinal cord injury

A novel, localized method for potential delivery of therapeutic agents to the injured spinal cord was investigated. The strategy consists of a polymeric drug solution that gels after injection into the subarachnoid space (SAS). By dispersing therapeutic agents in the polymeric solution, a method is provided for localized delivery to the spinal cord. To determine whether intrathecal injection of this drug delivery system (DDS) would affect cerebrospinal fluid (CSF) flow, a spinal canal model was built using dimensional analysis. Blocking up to 52% of the modeled subarachnoid space of the spinal canal caused minimal pressure differences (9.22 +/- 1.45 Pa), suggesting that implantation of a DDS would not subject the spinal cord to increased pressure. The safety of the DDS was also assessed in vivo by injecting collagen into the SAS of Sprague Dawley rats. Controls received injections of artificial CSF (aCSF). Collagen or aCSF was injected at the T2-T3 spinal level of both uninjured rats and rats injured with a 20g compression clip. The injected collagen persisted in the SAS for at least 8 weeks post-implantation and did not elicit an inflammatory reaction in either uninjured or injured animals. Long-term functional behavior was evaluated with the Basso, Beattie, and Bresnahan (BBB) scale weekly for 8 weeks. Functional behavior was similar in the collagen and aCSF groups, also indicating that the DDS was safe. This minimally invasive DDS may provide an alternative, safe method to deliver therapeutic agents intrathecally.