The International Spinal Cord Injury Pain Basic Data Set

Assessments of sensory plasticity after spinal cord injury across species

Spinal cord injury (SCI) is a multifaceted phenomenon associated with alterations in both motor function and sensory function. A majority of patients with SCI report sensory disturbances, including not only loss of sensation, but in many cases enhanced abnormal sensation, dysesthesia and pain. Development of therapeutics to treat these abnormal sensory changes require common measurement tools that can enable cross-species translation from animal models to human patients. We review the current literature on translational nociception/pain measurement in SCI and discuss areas for further development. Although a number of tools exist for measuring both segmental and affective sensory changes, we conclude that there is a pressing need for better, integrative measurement of nociception/pain outcomes across species to enhance precise therapeutic innovation for sensory dysfunction in SCI.

Intra-spinal microstimulation may alleviate chronic pain after spinal cord injury

Chronic pain after spinal cord injury (SCI) is a form of central neuropathic pain that is debilitating and often refractory to current pharmacological treatments. Neurostimulation pain therapies, such as epidural spinal cord stimulation, have only moderate success in reducing SCI pain. The pathogenesis of SCI pain may involve a state of central neuronal hyperexcitability, especially in the spinal cord dorsal horn, that develops after injury. We hypothesize that the neuronal structures near the spinal cord injury site may be an important pain generator, and intraspinal microstimulation (ISMS) may normalize dorsal horn neuronal hyperexcitability and hence alleviate SCI pain. Specifically, ISMS may induce frequency-dependent conduction block on axons of afferent sensory neurons, in the spinothalamic tract and Lissauer's tract. ISMS may also facilitate primary afferent depolarization that elicits presynaptic inhibition of incoming afferent inputs. Together, these actions will reduce abnormal afferent inputs and ascending pain signals before they can reach the brain. Furthermore, ISMS may directly induce inhibitory postsynaptic potentials in dorsal horn neurons, and trigger the release of endogenous inhibitory neurotransmitters, opioids and serotonin to inhibit postsynaptic neurons and restore the compromised segmental pain inhibition after SCI. Finally, ISMS may alter the frequency and pattern of discharge such that the rostrally conducted impulses no longer code pain or activate brain areas concerned with pain signaling. Based on recent progress in understanding spinal learning and plasticity, we also postulate that repetitive or long-term ISMS may help the dorsal horn "reset" neuronal excitability and regain normal pain processing for a prolonged period. By finely tuning the stimulation parameters (e.g., intensity, pulse width, frequency), position, and geometry of ISMS electrode, multiple spinal structures (e.g., dorsal horn, dorsal column, spinothalamic tract) may be modulated to induce synergistic pain inhibition. Our hypothesis can be readily tested in preclinical models of SCI pain by using a combination of in vivo electrophysiological (neuronal activity) and animal behavioral (pain response) approaches. Since ISMS electrodes stimulate the spinal structures directly, we expect that the effective stimulus intensity and energy consumption can be lower than that for epidural spinal cord stimulation. The proposed hypothesis may provide insights and rationales for developing a novel neurostimulation pain therapy by directly inhibiting the pain generators in the spinal cord, and ISMS may be an alternative strategy to treat SCI pain.

A randomized controlled trial of botulinum toxin A for treating neuropathic pain in patients with spinal cord injury

BACKGROUND

To assess the effect of botulinum toxin A (BTA) for treating neuropathic pain in patients with spinal cord injury (SCI).

METHODS

A total of 44 patients with SCI with neuropathic pain were randomly divided into the intervention group and the placebo group, each group 21 patients. The subjects in the intervention group received BTA (200 U subcutaneous injection, once daily) at the painful area, whereas those in the placebo group were administered a saline placebo. This study was conducted from December 2014 to November 2016. The primary outcome was measured using the visual analog scale (VAS). The secondary outcomes were measured using the short-form McGill Pain Questionnaire (SF-MPQ), and World Health Organization quality of life (WHOQOL-BREF) questionnaire. All outcome measurements were performed before and after 4 and 8 weeks of intervention.

RESULTS

Forty-one participants completed the study. The intervention with BTA showed greater efficacy than placebo in decreasing the VAS score after week 4 and week 8 of treatment. Significant differences in the SF-MPQ and WHOQOL-BREF were also found between the 2 groups.

CONCLUSION

The results of this study demonstrated that BTA might decrease intractable neuropathic pain for patients with SCI.

Outcomes and reflections on a consensus-building workshop for developing a spinal cord injury-related chronic pain research agenda

Context/ Objective: Chronic pain following spinal cord injury (SCI) is a prevalent secondary health condition that significantly impacts quality of life (QoL). Although growing, the number of available effective pain management approaches for SCI is limited. Recognizing the need to "kick-start" activity on this topic, a consensus-building workshop on developing a research agenda for SCI-related chronic pain was held in 2006 with an expert panel. The present paper describes the processes of the consensus-workshop and its associated outcomes towards advancing the research agenda for SCI-related pain in Canada. A commentary on the current state of knowledge regarding SCI-related pain is also provided.

METHODS

Thirty-nine stakeholders (researchers, clinicians, policy-makers, SCI advocates, and people with SCI) attended the consensus-workshop. A modified Delphi approach was employed to gain consensus on identifying the top five SCI pain research priorities for improving QoL post-SCI. As well, project planning along with infrastructure support opportunities were discussed.

RESULTS

The top five pain research priorities were: 1) pain management and treatment; 2) measurement tools; 3) health services policy and advocacy; 4) knowledge transfer; and 5) mechanisms of pain. Recommendations related to the priorities and related resources were generated, and pilot work was initiated.

CONCLUSIONS

The consensus workshop provided an initial roadmap for research on SCI-related chronic pain, and supported five pilot projects on the identified priorities. Reflections on the current research landscape in Canada and abroad suggest increased activity towards addressing pain post-SCI but evidence-based approaches are still lacking.

Safety of Autologous Human Schwann Cell Transplantation in Subacute Thoracic Spinal Cord Injury

The rationale for implantation of autologous human Schwann cells (SCs) in persons with subacute spinal cord injury (SCI) is based on evidence that transplanted SCs are neuroprotective, support local axonal plasticity, and are capable of myelinating axons. A Phase I clinical trial was conducted to evaluate the safety of autologous human SC transplantation into the injury epicenter of six subjects with subacute SCI. The trial was an open-label, unblinded, non-randomized, non-placebo controlled study with a dose escalation design and standard medical rehabilitation. Participants were paraplegics with neurologically complete, trauma-induced spinal lesions. Autologous SCs were cultured in vitro from a sural nerve harvested from each participant and injected into the epicenter of the spinal lesion. Outcome measures for safety were protocol compliance, feasibility, adverse events, stability of neurological level, absence of detectable mass lesion, and the emergence of clinically significant neuropathic pain or muscle spasticity no greater than expected for a natural course cohort. One year post-transplantation, there were no surgical, medical, or neurological complications to indicate that the timing or procedure for the cell transplantation was unsafe. There were no adverse events or serious adverse events related to the cell therapy. There was no evidence of additional spinal cord damage, mass lesion, or syrinx formation. We conclude that it is feasible to identify eligible candidates, appropriately obtain informed consent, perform a peripheral nerve harvest to obtain SCs within 5-30 days of injury, and perform an intra-spinal transplantation of highly purified autologous SCs within 4-7 weeks of injury.

Ultramicronized palmitoylethanolamide in spinal cord injury neuropathic pain: a randomized, double-blind, placebo-controlled trial

Neuropathic pain and spasticity after spinal cord injury (SCI) represent significant problems. Palmitoylethanolamide (PEA), a fatty acid amide that is produced in many cells in the body, is thought to potentiate the action of endocannabinoids and to reduce pain and inflammation. This randomized, double-blind, placebo-controlled, parallel multicenter study was performed to investigate the effect of ultramicronized PEA (PEA-um) as add-on therapy on neuropathic pain in individuals with SCI. A pain diary was completed and questionnaires were completed before and after the 12-week treatment with either placebo or PEA-um. The primary outcome measure was the change in mean neuropathic pain intensity from the 1-week baseline period to the last week of treatment measured on a numeric rating scale ranging from 0 to 10. The primary efficacy analysis was the intention to treat (baseline observation carried forward). Secondary outcomes included a per protocol analysis and effects on spasticity, evoked pain, sleep problems, anxiety, depression, and global impression of change. We randomized 73 individuals with neuropathic pain due to SCI, of which 5 had a major protocol violation, and thus 68 were included in the primary analysis. There was no difference in mean pain intensity between PEA-um and placebo treatment (P = 0.46, mean reductions in pain scores 0.4 (-0.1 to 0.9) vs 0.7 (0.2-1.2); difference of means 0.3 (-0.4 to 0.9)). There was also no effect of PEA-um as add-on therapy on spasticity, insomnia, or psychological functioning. PEA was not associated with more adverse effects than placebo.

Surgical Neurostimulation for Spinal Cord Injury

Traumatic spinal cord injury (SCI) is a devastating neurological condition characterized by a constellation of symptoms including paralysis, paraesthesia, pain, cardiovascular, bladder, bowel and sexual dysfunction. Current treatment for SCI involves acute resuscitation, aggressive rehabilitation and symptomatic treatment for complications. Despite the progress in scientific understanding, regenerative therapies are lacking. In this review, we outline the current state and future potential of invasive and non-invasive neuromodulation strategies including deep brain stimulation (DBS), spinal cord stimulation (SCS), motor cortex stimulation (MCS), transcutaneous direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) in the context of SCI. We consider the ability of these therapies to address pain, sensorimotor symptoms and autonomic dysregulation associated with SCI. In addition to the potential to make important contributions to SCI treatment, neuromodulation has the added ability to contribute to our understanding of spinal cord neurobiology and the pathophysiology of SCI.

Living With Chronic Pain After Spinal Cord Injury: A Mixed-Methods Study

OBJECTIVE

To identify the relative importance of positive (facilitators) and negative (barriers) contributors to living with chronic pain after spinal cord injury (SCI).

DESIGN

Mixed-methods: (1) Qualitative (n=35): individual, semistructured, open-ended interviews identifying facilitator/barrier themes; (2) Quantitative (n=491): converting the most common themes into statements and quantifying agreement with these in an online survey to determine relative importance, underlying dimensions, and their associations with perceived difficulty in dealing with pain.

SETTING

University-based research setting and general community.

PARTICIPANTS

Volunteers (N=526) with SCI experiencing moderate to severe chronic pain.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Interview guides, facilitator/barrier statements, and pain inventories.

RESULTS

Exploratory factor analyses reduced agreement ratings into 4 facilitators (information regarding pain and treatments, resilience, coping, medication use) and 5 barriers (poor health care communication, pain impact and limitations, poor communication about pain, difficult nature of pain, treatment concerns). Greater "pain impact and limitations," "difficult nature of pain," "poor communication from provider," lower "resilience," greater "medication use," and younger age predicted greater difficulty in dealing with pain (r=.75; F=69.02; P<.001).

CONCLUSIONS

This study revealed multiple facilitators and barriers to living with chronic pain after SCI. The principal barrier, "poor health care communication," indicated that consumers do not receive adequate information from their health care providers regarding pain. "Information regarding pain and treatments" had greater agreement scores and factor loadings than all other facilitators, indicating that most participants view provider-patient communication and educational efforts regarding pain and pain management as priorities and critical needs. Further initiatives in these areas are important for improving pain management post-SCI.

Prevalence and associated factors of pain in the Swiss spinal cord injury population

STUDY DESIGN

Population-based, cross-sectional.

OBJECTIVES

To determine pain prevalence and identify factors associated with chronic pain in individuals with spinal cord injury (SCI) living in Switzerland.

SETTING

Swiss SCI Cohort Study (SwiSCI).

METHODS

Pain characteristics were assessed using an adapted version of the International SCI Pain Basic Data Set, adding one item of the SCI Secondary Conditions Scale to address chronic pain. Pain prevalence was calculated using stratification over demographic, SCI-related and socioeconomic characteristics; odds ratios (adjusted for non-response) for determinants of severity of chronic pain were calculated using stereotype logistic regressions.

RESULTS

Pain (in the past week) was reported by 68.9% and chronic pain by 73.5% (significant 36.9%) of all participants (N=1549; 28% female). Most frequently reported pain type was musculoskeletal (71.1%). Back/spine was the most frequently reported pain location (54.6%). Contrasting the 'significant' to the 'none/mild' category of chronic pain, adjusted odds ratios were 1.54 (95% CI: 1.18-2.01; P<0.01) for women (vs men); 6.64 (95% CI: 3.37-11.67; P<0.001) for the oldest age group 61+ (vs youngest (16-30)); 3.41 (95% CI: 2.07-5.62; P<0.001) in individuals reporting severe financial hardship (vs no financial hardship). Individuals reporting specific SCI-related health conditions were 1.41-2.92 (P<0.05) times more likely to report chronic pain as 'significant' rather than 'none/mild' compared with those without the respective condition.

CONCLUSIONS

Pain is highly prevalent in individuals with SCI living in Switzerland. Considered at risk for chronic pain are women, older individuals and individuals with financial hardship and specific secondary health conditions. Longitudinal studies are necessary to identify predictors for the development of pain and its chronification.

Changes in pain and quality of life in depressed individuals with spinal cord injury: does type of pain matter?

OBJECTIVE

To examine the association of neuropathic and nociceptive pain severity and interference with quality of life (QoL) in persons with spinal cord injury (SCI) who underwent a randomized controlled 12-week trial of an antidepressant to treat depression. A secondary objective was to assess the effect of changes in pain on mobility and physical independence.

DESIGN

Multivariable ANCOVA models controlling for relevant demographic covariates, treatment condition, and baseline pain and QoL were used.

SETTING

Six rehabilitation centers.

PARTICIPANTS

Of the 133 persons who were randomized into the trial, 108 provided pain severity and interference ratings through follow-up.

INTERVENTIONS

Not applicable.

OUTCOME MEASURES

The Satisfaction with Life Scale and the physical and mental component summary scores of the 12-Item Short-Form Health Survey (SF-12). Secondary outcome measures included the mobility and physical independence subscales of the Craig Handicap Assessment and Reporting Technique (CHART).

RESULTS

Broadly, few associations between pain and QoL were evident. Results revealed relationships between lower baseline nociceptive pain interference and higher satisfaction with life and mental health-related QoL at 12 weeks. Similarly, lower neuropathic pain interference was associated with change in physical independence, but unrelated to mobility.

CONCLUSIONS

Pain interference over time may be differentially related to QoL outcomes based on the type of pain following SCI, but overall, there were no extensive relationships between pain and QoL in this sample of depressed persons with SCI.

Standardization of Data for Clinical Use and Research in Spinal Cord Injury

Increased survival after spinal cord injury (SCI) worldwide has enhanced the need for quality data that can be compared and shared between centers, countries, as well as across research studies, to better understand how best to prevent and treat SCI. Such data should be standardized and be able to be uniformly collected at any SCI center or within any SCI study. Standardization will make it possible to collect information from larger SCI populations for multi-center research studies. With this aim, the international SCI community has obtained consensus regarding the best available data and measures for use in SCI clinical practice and research. Reporting of SCI data is likewise standardized. Data elements are continuously updated and developed using an open and transparent process. There are ongoing internal, as well as external review processes, where all interested parties are encouraged to participate. The purpose of this review paper is to provide an overview of the initiatives to standardize data including the International Spinal Cord Society's International SCI Data Sets and the National Institutes of Health, National Institute of Neurological Disorders and Stroke Common Data Elements Project within SCI and discuss future opportunities.

Psychosocial aspects of spinal cord injury pain: a meta-analysis

STUDY DESIGN

Meta-analysis.

OBJECTIVES

Although the association between modifiable psychosocial factors and spinal cord injury (SCI) pain has been identified, the full range of psychological and social difficulties for those who experience acute and/or persistent pain remains unclear. This meta-analysis consolidates the available evidence, using the International Classification of Functioning, Disability and Health (ICF) as a reference framework.

METHODS

Nineteen studies that examined persistent neuropathic, nociceptive or mixed pain subtypes in adults with a SCI (newly acquired and chronic; Nparticipants=2934) were identified from electronic database searches. Standardised mean differences between SCI pain and no-pain groups on self-reported psychosocial outcomes were calculated, along with 95% confidence intervals, fail-safe Ns and heterogeneity statistics.

RESULTS

Twenty individual outcomes were grouped into nine ICF-related categories. Emotional functions were the most frequent (100%) psychosocial outcomes assessed, with pain contributing to heightened stress (d=-0.85), depression (d=-2.49) anxiety (d range=-0.85 to -1.45), poor self-efficacy (d=-0.77), lowered wellbeing (d range=-0.67 to -1.02) and decreased use of adaptive coping, such as illness acceptance (d=-0.85). Activity limitations and participation restriction were examined by seven studies (43%), although these findings were largely characterised by single studies.

CONCLUSIONS

Multicomponent treatments that target mood disturbance and foster community connections are important in SCI pain management. However, to improve the comparability of future studies, SCI pain research must adopt definitions of pain consistent with the International Spinal Cord Injury Pain Classification along with validated outcomes that map onto the ICF framework.

Botulinum toxin type A for neuropathic pain in patients with spinal cord injury

Objective

To evaluate the analgesic effect of botulinum toxin type A (BTX‐A) on patients with spinal cord injury‐associated neuropathic pain.

Methods

The effect of BTX‐A on 40 patients with spinal cord injury‐associated neuropathic pain was investigated using a randomized, double‐blind, placebo‐controlled design. A 1‐time subcutaneous BTX‐A (200U) injection was administered to the painful area. Visual analogue scale (VAS) scores (0–100mm), the Korean version of the short‐form McGill Pain Questionnaire, and the World Health Organization WHOQOL‐BREF quality of life assessment were evaluated prior to treatment and at 4 and 8 weeks after the injection.

Results

At 4 and 8 weeks after injection, the VAS score for pain was significantly reduced by 18.6 ± 16.8 and 21.3 ± 26.8, respectively, in the BTX‐A group, whereas it was reduced by 2.6 ± 14.6 and 0.3 ± 19.5, respectively, in the placebo group. The pain relief was associated with preservation of motor or sensory function below the neurological level of injury. Among the responders in the BTX‐A group, 55% and 45% reported pain relief of 20% or greater at 4 and 8 weeks, respectively, after the injection, whereas only 15% and 10% of the responders in the placebo group reported a similar level of pain relief. Improvements in the score for the physical health domain of the WHOQOL‐BREF in the BTX‐A group showed a marginal trend toward significance (p = 0.0521) at 4 weeks after the injection.

Interpretation

These results indicate that BTX‐A may reduce intractable chronic neuropathic pain in patients with spinal cord injury. Ann Neurol 2016;79:569–578

Analysis of the behavioral, cellular and molecular characteristics of pain in severe rodent spinal cord injury

Human SCI is frequently associated with chronic pain that is severe and refractory to medical therapy. Most rodent models used to assess pain outcomes in SCI apply moderate injuries to lower thoracic spinal levels, whereas the majority of human lesions are severe in degree and occur at cervical or upper thoracic levels. To better model and understand mechanisms associated with chronic pain after SCI, we subjected adult rats to T3 severe compression or complete transection lesions, and examined pain-related behaviors for three months. Within one week after injury, rats developed consistent forepaw pain-related behaviors including increased spontaneous lifts, tactile allodynia and cold sensitivity that persisted for three months. Place escape avoidance testing confirmed that withdrawal of the forepaws from a von Frey stimulus represented active pain-related aversion. Spontaneous and evoked pain-related measures were attenuated by gabapentin, further indicating that these behaviors reflect development of pain. Spinal level of injury was relevant: rats with T11 severe SCI did not exhibit forepaw pain-related behaviors. Immunoblotting and immunofluorescence of C6-C8 spinal dorsal horn, reflecting sensory innervation of the forepaw, revealed: 1) expansion of CGRP immunoreactivity in lamina I/II; 2) increased GAP-43 expression; and 3) increased IBA1, GFAP and connexin-43 expression. These findings indicate that aberrant pain fiber sprouting and gliopathy occur after severe SCI. Notably, satellite glial cells (SGCs) in C6-C8 DRGs exhibited increases in GFAP and connexin-43, suggesting ongoing peripheral sensitization. Carbenoxolone, a gap junction inhibitor, and specific peptide inhibitors of connexin-43, ameliorated established tactile allodynia after severe SCI. Collectively, severe T3 SCI successfully models persistent pain states and could constitute a useful model system for examining candidate translational pain therapies after SCI.

The midbrain central gray best suppresses chronic pain with electrical stimulation at very low pulse rates in two human cases

Deep brain stimulation in the midbrain׳s central gray can relieve neuropathic pain in man, but for unclear reasons sometimes fails intraoperatively or in early weeks. Here we describe continuous bilateral stimulation in the central gray of two subjects with longstanding, severe neuropathic pain from spinal cord injury. Stimulation parameters were recursively adjusted over many weeks to optimize analgesia while minimizing adverse effects. In early weeks, adjustments were made in periodic office visits; subjects later selected ad libitum at home among several blinded choices while rating pain twice daily. Both subjects received significantly better pain relief when stimulus pulse rates were low. The best relief occurred with 2 Hz cycled on for 1s and off for 2s. After inferior parameters were set, pain typically climbed slowly over 1-2 days; superior parameters led to both slow and fast improvements. Over many weeks of stimulation at low pulse rates, both subjects experienced significantly less interference from pain with sleep. One subject, with major pain relief, also showed less interference with social/recreational ability and mood; the other subject, despite minor pain relief, experienced a significantly positive global impression of change. Oscillopsia, the only observed complication of stimulation, disappeared at low mean pulse rates (≤ 3/s). These subjects׳ responses are not likely to be unique even if they are uncommon. Thus daily or more frequent pain assessment, combined with slower periodic adjustment of stimulation parameters that incorporate mean pulse rates about one per second, will likely improve success with this treatment.

Capsaicin 8% Patch for Central and Peripheral Neuropathic Pain of Persons with Incomplete Spinal Cord Injury: Two Case Reports

Neuropathic pain after spinal cord injury is common and often refractory to standard treatments. The capsaicin 8% patch is a Food and Drug Administration-approved treatment of neuropathic pain in postherpetic neuralgia and has demonstrated significant efficacy in human immunodeficiency virus-autonomic neuropathy. The patch defunctionalizes transient receptor potential vanilloid 1 receptors, impairing cutaneous nociceptors for a prolonged period (i.e., 8-12 wks) with no systemic side effects. A retrospective review was conducted on the effects of the patch in two patients with spinal cord injury and neuropathic pain refractory to standard treatments. Two weeks after application, both patients reported complete pain relief. Average onset of relief of 4 days and average duration of relief of 197 days, requiring only one to four applications per year, paralleled findings reported in postherpetic neuralgia and human immunodeficiency virus-autonomic neuropathy trials. Upregulation of capsaicin-sensitive transient receptor potential vanilloid 1 receptors after spinal cord injury has been reported. The capsaicin 8% patch is a promising therapeutic agent for neuropathic pain in spinal cord injury.

Association of Shoulder Problems in Persons With Spinal Cord Injury at Discharge From Inpatient Rehabilitation With Activities and Participation 5 Years Later

OBJECTIVE

To examine whether musculoskeletal shoulder pain and limitations in shoulder range of motion (ROM) at discharge from first rehabilitation are associated with activities and participation restrictions 5 years later in persons with spinal cord injury (SCI).

DESIGN

Prospective cohort study.

SETTING

Eight specialized SCI rehabilitation centers.

PARTICIPANTS

Subjects (N=138) with an SCI admitted for first rehabilitation.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Peak power output (POpeak), Wheelchair Skills Test (WST), FIM motor score, ability to transfer, Physical Activity Scale for Individuals with Physical Disabilities (PASIPD), mobility range and social behavior subscales of the Sickness Impact Profile 68 (SIPSOC), and employment status.

RESULTS

Mean age of the subjects at discharge was 39 years, 72% were men, 32% had tetraplegia, and in 65% the SCI was motor complete. At discharge, 39% reported shoulder pain and 32% had a limited shoulder ROM. In the analyses of variance, shoulder ROM limitation, but not shoulder pain, was associated with all but 1 outcome at 5 years. In the regression analyses, ROM limitations of the shoulder were negatively associated with the ability to transfer (P=.004), FIM motor scores (P<.001), and return to work (P= .027) 5 years after discharge. No significant associations were found with POpeak, WST performance time, SIPSOC, and PASIPD.

CONCLUSIONS

The presence of limitations in shoulder ROM, but not shoulder pain, at discharge is associated with limitations in activities and employment status 5 years later.

PI3K mediated activation of GSK-3β reduces at-level primary afferent growth responses associated with excitotoxic spinal cord injury dysesthesias

Background

Neuropathic pain and sensory abnormalities are a debilitating secondary consequence of spinal cord injury (SCI). Maladaptive structural plasticity is gaining recognition for its role in contributing to the development of post SCI pain syndromes. We previously demonstrated that excitotoxic induced SCI dysesthesias are associated with enhanced dorsal root ganglia (DRG) neuronal outgrowth. Although glycogen synthase kinase-3β (GSK-3β) is a known intracellular regulator neuronal growth, the potential contribution to primary afferent growth responses following SCI are undefined. We hypothesized that SCI triggers inhibition of GSK-3β signaling resulting in enhanced DRG growth responses, and that PI3K mediated activation of GSK-3β can prevent this growth and the development of at-level pain syndromes.

Results

Excitotoxic SCI using intraspinal quisqualic acid (QUIS) resulted in inhibition of GSK-3β in the superficial spinal cord dorsal horn and adjacent DRG. Double immunofluorescent staining showed that GSK-3β^P was expressed in DRG neurons, especially small nociceptive, CGRP and IB4-positive neurons. Intrathecal administration of a potent PI3-kinase inhibitor (LY294002), a known GSK-3β activator, significantly decreased GSK-3β^P expression levels in the dorsal horn. QUIS injection resulted in early (3 days) and sustained (14 days) DRG neurite outgrowth of small and subsequently large fibers that was reduced with short term (3 days) administration of LY294002. Furthermore, LY294002 treatment initiated on the date of injury, prevented the development of overgrooming, a spontaneous at-level pain related dysesthesia.

Conclusions

QUIS induced SCI resulted in inhibition of GSK-3β in primary afferents and enhanced at-level DRG intrinsic growth (neurite elongation and initiation). Early PI3K mediated activation of GSK-3β attenuated QUIS-induced DRG neurite outgrowth and prevented the development of at-level dysesthesias.

Management of Neuropathic Pain Associated with Spinal Cord Injury

Spinal cord injury (SCI) is an injury to the spinal cord that leads to varying degrees of motor and/or sensory deficits and paralysis. Chronic pain of both neuropathic and nociceptive type is common and contributes to reduced quality of life. The aim of the review is to provide current clinical understanding as well as discuss and evaluate efficacy of pharmacological interventions demonstrated in the clinical studies. The review was based on literature search in PubMed and Medline with words "neuropathic pain" and "spinal cord injury". The review included clinical studies and not experimental data nor case reports. A limited number of randomized and placebo-controlled studies concerning treatment options of neuropathic pain after SCI were identified. Amitriptyline, a tricyclic antidepressant and the antiepileptic drugs, gabapentin and pregabalin, are most studied with demonstrated efficacy, and considered to be the primary choice. Opioids have demonstrated conflicting results in the clinical studies. In addition, administration route used in the studies as well as reported side effects restrict everyday use of opioids as well as ketamine and lidocaine. Topical applications of capsaicin or lidocaine as well as intradermal injections of Botulinum toxin are new treatment modalities that are so far not studied on SCI population and need further studies. Non-pharmacological approaches may have additional effect on neuropathic pain. Management of pain should always be preceded by thorough clinical assessment of the type of pain. Patients need a follow-up to evaluate individual effect of applied measures. However, the applied management does not necessarily achieve satisfactory pain reduction. Further clinical studies are needed to evaluate the effect of both established and novel management options.

Evaluation of pain and its effect on quality of life and functioning in men with spinal cord injury

Background

Pain is one of the most important consequences of spinal cord injury (SCI). It may affect several aspects of life, especially the quality of life (QoL). Hence, this study was conducted to establish an understanding of pain and its correlates and effects on patients with SCI in our community.

Methods

In a cross-sectional study, 58 male veterans suffering from SCI were admitted to our center for a regular follow-up. Demographic and SCI-related descriptive information were gathered using a self-reported questionnaire. To evaluate the patients' pain quality and the effect of pain on daily life, a questionnaire in 3 parts of lumbar, cervical and shoulder pain was administered. EuroQoL questionnaire and General Health Questionnaire (GHQ) 12 were also used to assess the patients' QoL.

Results

The mean age of the participants was 45.91 ± 6.69 with mean injury time of 25.54 ± 5.91. forty-four patients (75.9%) reported pain, including lumbar pain (63%), cervical pain (39%) and shoulder pain (51%). The presence of pain was associated with lower QoL. Patients with lumbar pain reported a significant amount of pain affecting their daily life and this effect was higher in patients with lower GHQ score or anxiety/depressive disorder.

Conclusions

Musculoskeletal pain, is a common complaint in veterans with SCI and is inversely associated with functioning and general health status. Lumbar and shoulder pain affects patient's daily living more than cervical pain.

Effect of subcutaneous injection of botulinum toxin A on spinal cord injury-associated neuropathic pain

STUDY DESIGN

Case report.

OBJECTIVE

To present a case of spinal cord injury (SCI)-associated neuropathic pain treated with botulinum toxin A injection.

SETTING

Outpatient SCI clinic.

CASE REPORT

Description of a case in the context of relevant literature on the subject.

RESULTS

A 51-year-old man with C3 AIS B tetraplegia (American Spinal Injury Association Impairment Scale B) visited our outpatient clinic due to severe ongoing neuropathic pain and associated allodynia and dysesthesia of the lower limbs. He had previously tried combinations of pregabalin, gabapentin and oxycontin but all failed to alleviate his neuropathic pain during the 2 years post trauma. With the patient's consent, he was treated with subcutaneous injections of clostridium type A botulinum toxin. Ten units of type A botulinum toxin subcutaneously injected into 10 most painful sites of each sole. The patient was reassessed at 4 and 8 weeks after his injection with botulinum toxin with significant improvement of his neuropathic pain.

CONCLUSION

Subcutaneous injection of type A botulinum toxin was effective without side effects, on one case of refractory neuropathic pain due to SCI. This is the first article to report the use of type A botulinum toxin in neuropathic pain related to traumatic SCI.

Non-pharmacological interventions for chronic pain in people with spinal cord injury

BACKGROUND

Chronic pain is frequent in persons living with spinal cord injury (SCI). Conventionally, the pain is treated pharmacologically, yet long-term pain medication is often refractory and associated with side effects. Non-pharmacological interventions are frequently advocated, although the benefit and harm profiles of these treatments are not well established, in part because of methodological weaknesses of available studies.

OBJECTIVES

To critically appraise and synthesise available research evidence on the effects of non-pharmacological interventions for the treatment of chronic neuropathic and nociceptive pain in people living with SCI.

SEARCH METHODS

The search was run on the 1st March 2011. We searched the Cochrane Injuries Group's Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (OvidSP), Embase (OvidSP), PsycINFO (OvidSP), four other databases and clinical trials registers. In addition, we manually searched the proceedings of three major scientific conferences on SCI. We updated this search in November 2014 but these results have not yet been incorporated.

SELECTION CRITERIA

Randomised controlled trials of any intervention not involving intake of medication or other active substances to treat chronic pain in people with SCI.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed risk of bias in the included studies. The primary outcome was any measure of pain intensity or pain relief. Secondary outcomes included adverse events, anxiety, depression and quality of life. When possible, meta-analyses were performed to calculate standardised mean differences for each type of intervention.

MAIN RESULTS

We identified 16 trials involving a total of 616 participants. Eight different types of interventions were studied. Eight trials investigated the effects of electrical brain stimulation (transcranial direct current stimulation (tDCS) and cranial electrotherapy stimulation (CES); five trials) or repetitive transcranial magnetic stimulation (rTMS; three trials). Interventions in the remaining studies included exercise programmes (three trials); acupuncture (two trials); self-hypnosis (one trial); transcutaneous electrical nerve stimulation (TENS) (one trial); and a cognitive behavioural programme (one trial). None of the included trials were considered to have low overall risk of bias. Twelve studies had high overall risk of bias, and in four studies risk of bias was unclear. The overall quality of the included studies was weak. Their validity was impaired by methodological weaknesses such as inappropriate choice of control groups. An additional search in November 2014 identified more recent studies that will be included in an update of this review.For tDCS the pooled mean difference between intervention and control groups in pain scores on an 11-point visual analogue scale (VAS) (0-10) was a reduction of -1.90 units (95% confidence interval (CI) -3.48 to -0.33; P value 0.02) in the short term and of -1.87 (95% CI -3.30 to -0.45; P value 0.01) in the mid term. Exercise programmes led to mean reductions in chronic shoulder pain of -1.9 score points for the Short Form (SF)-36 item for pain experience (95% CI -3.4 to -0.4; P value 0.01) and -2.8 pain VAS units (95% CI -3.77 to -1.83; P value < 0.00001); this represented the largest observed treatment effects in the included studies. Trials using rTMS, CES, acupuncture, self-hypnosis, TENS or a cognitive behavioural programme provided no evidence that these interventions reduce chronic pain. Ten trials examined study endpoints other than pain, including anxiety, depression and quality of life, but available data were too scarce for firm conclusions to be drawn. In four trials no side effects were reported with study interventions. Five trials reported transient mild side effects. Overall, a paucity of evidence was found on any serious or long-lasting side effects of the interventions.

AUTHORS' CONCLUSIONS

Evidence is insufficient to suggest that non-pharmacological treatments are effective in reducing chronic pain in people living with SCI. The benefits and harms of commonly used non-pharmacological pain treatments should be investigated in randomised controlled trials with adequate sample size and study methodology.

Loss of central inhibition: implications for behavioral hypersensitivity after contusive spinal cord injury in rats

Behavioral hypersensitivity is common following spinal cord injury (SCI), producing significant discomfort and often developing into chronic pain syndromes. While the mechanisms underlying the development of behavioral hypersensitivity after SCI are poorly understood, previous studies of SCI contusion have shown an increase in amino acids, namely, aspartate and glutamate, along with a decrease in GABA and glycine, particularly below the injury. The current study sought to identify alterations in key enzymes and receptors involved in mediating central inhibition via GABA and glycine after a clinically-relevant contusion SCI model. Following thoracic (T8) 25.0 mm NYU contusion SCI in rodents, significant and persistent behavioral hypersensitivity developed as evidenced by cutaneous allodynia and thermal hyperalgesia. Biochemical analyses confirmed upregulation of glutamate receptor GluR3 with downregulation of the GABA synthesizing enzyme (GAD_65/67) and the glycine receptor α3 (GLRA3), notably below the injury. Combined, these changes result in the disinhibition of excitatory impulses and contribute to behavioral hyperexcitability. This study demonstrates a loss of central inhibition and the development of behavioral hypersensitivity in a contusive SCI paradigm. Future use of this model will permit the evaluation of different antinociceptive strategies and help in the elucidation of new targets for the treatment of neuropathic pain.

The effect of repetitive transcranial magnetic stimulation on refractory neuropathic pain in spinal cord injury

OBJECTIVE

To investigate the analgesic effect of repetitive transcranial magnetic stimulation (rTMS) on intractable neuropathic pain in patients with spinal cord injury (SCI).

DESIGN

A single center, prospective, randomized, double-blinded, controlled study.

SETTING

SCI rehabilitation unit of university rehabilitation center.

PARTICIPANTS

Seventeen patients with SCI and chronic neuropathic pain who met the inclusion criteria recruited between April 2010 and January 2012.

INTERVENTIONS

Ten daily treatment sessions of real or sham rTMS (30 trains of 10-Hz stimuli for a duration of 5 seconds; a total of 1500 pulses at intensity equal to 110% of the resting motor threshold) was applied over vertex using a figure-of-8-shaped coil.

OUTCOME MEASURES

Pain was assessed with visual analog scale (VAS) at baseline and 10 days, 6 weeks and 6 months after the treatment. Patients' satisfactions obtained using a 5-point Likert scale at 6 months.

RESULTS

Both real and sham rTMS provided a significant reduction in the VAS scores (real rTMS group, P = 0.004; sham rTMS group, P = 0.020). Post hoc analysis revealed the significant difference was at 10 days and 6 weeks compared to baseline in the real rTMS group and only at 10 days compared to baseline in the sham rTMS group. Comparison of VAS scores and patient satisfaction did not show any significant difference at each assessment point (P > 0.05).

CONCLUSION

Our results demonstrated analgesic effect of rTMS on intractable neuropathic pain in SCI was not superior to placebo. However, middle-term (over 6 weeks) pain relief by rTMS is encouraging and suggests the need for future studies with a larger sample size.

Understanding therapeutic benefits of overground bionic ambulation: exploratory case series in persons with chronic, complete spinal cord injury

OBJECTIVE

To explore responses to overground bionic ambulation (OBA) training from an interdisciplinary perspective including key components of neuromuscular activation, exercise conditioning, mobility capacity, and neuropathic pain.

DESIGN

Case series.

SETTING

Academic research center.

PARTICIPANTS

Persons (N=3; 2 men, 1 woman) aged 26 to 38 years with complete spinal cord injury (SCI) (American Spinal Injury Association Impairment Scale grade A) between the levels of T1 and T10 for ≥1 year.

INTERVENTION

OBA 3d/wk for 6 weeks.

MAIN OUTCOME MEASURES

To obtain a comprehensive understanding of responses to OBA, an array of measures were obtained while walking in the device, including walking speeds and distances, energy expenditure, exercise conditioning effects, and neuromuscular and cortical activity patterns. Changes in spasticity and pain severity related to OBA use were also assessed.

RESULTS

With training, participants were able to achieve walking speeds and distances in the OBA device similar to those observed in persons with motor-incomplete SCI (10-m walk speed, .11-.33m/s; 2-min walk distance, 11-33m). The energy expenditure required for OBA was similar to walking in persons without disability (ie, 25%-41% of peak oxygen consumption). Subjects with lower soleus reflex excitability walked longer during training, but there was no change in the level or amount of muscle activity with training. There was no change in cortical activity patterns. Exercise conditioning effects were small or nonexistent. However, all participants reported an average reduction in pain severity over the study period ranging between -1.3 and 1.7 on a 0-to-6 numeric rating scale.

CONCLUSIONS

OBA training improved mobility in the OBA device without significant changes in exercise conditioning or in neuromuscular or cortical activity. However, pain severity was reduced and no severe adverse events were encountered during training. OBA therefore opens the possibility to reduce the common consequences of chronic, complete SCI such as reduced functional mobility and neuropathic pain.

Trajectories of musculoskeletal shoulder pain after spinal cord injury: Identification and predictors

OBJECTIVE/BACKGROUND

Although shoulder pain is a problem in up to 86% of persons with a spinal cord injury (SCI), so far, no studies have empirically identified longitudinal patterns (trajectories) of musculoskeletal shoulder pain after SCI. The objective of this study was: (1) to identify distinct trajectories of musculoskeletal shoulder pain in persons with SCI, and (2) to determine possible predictors of these trajectories.

DESIGN/METHODS

Multicenter, prospective cohort study in 225 newly injured persons with SCI.

OUTCOME MEASURE

Shoulder pain was assessed on five occasions up to 5 years after discharge. Latent class growth mixture modeling was used to identify the distinct shoulder pain trajectories.

RESULTS

Three distinct shoulder pain trajectories were identified: (1) a "No or Low pain" trajectory (64%), (2) a "High pain" (30%) trajectory, and (3) a trajectory with a "Decrease of pain" (6%). Compared with the "No or Low pain" pain trajectory, the "High pain" trajectory consisted of more persons with tetraplegia, shoulder pain before injury, limited shoulder range of motion (ROM), lower manual muscle test scores, or more spasticity at t1. Multiple logistic regression analysis showed two significant predictors for the "High pain" trajectory (as compared with the "No or Low pain" trajectory): having a tetraplegia (odds ratio (OR) = 3.2; P = 0.002) and having limited shoulder ROM (OR = 2.8; P = 0.007).

CONCLUSION

Shoulder pain in people with SCI follows distinct trajectories. At risk for belonging to the "High pain" trajectory are persons with tetraplegia and those with a limited shoulder ROM at start of active rehabilitation.

Acute exercise prevents the development of neuropathic pain and the sprouting of non-peptidergic (GDNF- and artemin-responsive) c-fibers after spinal cord injury

Spinal cord injury (SCI) impaired sensory fiber transmission leads to chronic, debilitating neuropathic pain. Sensory afferents are responsive to neurotrophic factors, molecules that are known to promote survival and maintenance of neurons, and regulate sensory neuron transduction of peripheral stimuli. A subset of primary afferent fibers responds only to the glial cell-line derived neurotrophic factor (GDNF) family of ligands (GFLs) and is non-peptidergic. In peripheral nerve injury models, restoration of GDNF or artemin (another GFL) to pre-injury levels within the spinal cord attenuates neuropathic pain. One non-invasive approach to increase the levels of GFLs in the spinal cord is through exercise (Ex), and to date exercise training is the only ameliorative, non-pharmacological treatment for SCI-induced neuropathic pain. The purpose of this study was 3-fold: 1) to determine whether exercise affects the onset of SCI-induced neuropathic pain; 2) to examine the temporal profile of GDNF and artemin in the dorsal root ganglia and spinal cord dorsal horn regions associated with forepaw dermatomes after SCI and Ex; and 3) to characterize GFL-responsive sensory fiber plasticity after SCI and Ex. Adult, female, Sprague-Dawley rats received a moderate, unilateral spinal cord contusion at C5. A subset of rats was exercised (SCI+Ex) on automated running wheels for 20min, 5days/week starting at 5days post-injury (dpi), continuing until 9 or 37dpi. Hargreaves' and von Frey testing was performed preoperatively and weekly post-SCI. Forty-two percent of rats in the unexercised group exhibited tactile allodynia of the forepaws while the other 58% retained normal sensation. The development of SCI-induced neuropathic pain correlated with a marked decrease in the levels of GDNF and artemin in the spinal cord and DRGs. Additionally, a dramatic increase in the density and the distribution throughout the dorsal horn of GFL-responsive afferents was observed in rats with SCI-induced allodynia. Importantly, in SCI rats that received Ex, the incidence of tactile allodynia decreased to 7% (1/17) and there was maintenance of GDNF and artemin at normal levels, with a normal distribution of GFL-responsive fibers. These data suggest that GFLs and/or their downstream effectors may be important modulators of pain fiber plasticity, representing effective targets for anti-allodynic therapeutics. Furthermore, we highlight the potent beneficial effects of acute exercise after SCI.

Moving towards multiple site outcomes in spinal cord injury pain clinical trials: An issue of clustered observations in trial design and analysis

INTRODUCTION

Pain remains a problem for many with spinal cord injury (SCI), and there is a need for sound, randomized clinical trials examining the efficacy of existing and novel therapeutics. SCI-related pain is complex, as more than one type of pain is often experienced. The purpose of this report is to (i) demonstrate how to design and power calculation of a clinical trial of SCI pain using multiple pain sites per individual; (ii) discuss consequences of failing to adjust for this; and (iii) provide intraclass correlation (ICC) estimates for common pain outcome measures that may be used to power future clinical trials in SCI pain.

METHOD

Using an existing dataset from a past SCI pain clinical trial, the ICC was calculated for common pain outcome measures to illustrate appropriate corrections for powering, analyzing and interpreting results from multiple pain sites per individual. The problem associated with not accounting for multiple pain sites per individual and the effect on the Type I error rate is also shown.

RESULTS AND DISCUSSION

Not accounting for the ICC can lead to (1) incorrect power estimates in the design of a trial, and (2) an inflated Type I error rate with a higher likelihood of misinterpretation of outcomes.

CONCLUSIONS

Powering for future SCI pain trials and statistical analysis of trial outcomes may be substantially compromised if methods do not account for the intra-individual associations between pain sites, ultimately affecting study interpretations and evidence-based practice. We present ICC estimates based on SCI pain data for purposes of estimating power for future trials.

Multidimensional clinical pain phenotypes after spinal cord injury

SUMMARY Persistent neuropathic pain after spinal cord injury (SCI) is a serious problem that significantly affects general health and wellbeing over and above what is caused by other medical consequences after SCI. The ideal approach to the management of the neuropathic pain conditions after SCI would be to identify the primary contributing mechanisms of pain in each person and tailor the treatment to these. However, despite significant basic and clinical research progress, this approach remains elusive. One strategy to further this effort is to define neuropathic pain phenotypes based on pain symptoms, sensory function/dysfunction and psychosocial factors, and determine the relationship between these and treatment outcomes and biomarkers including brain imaging. This approach will facilitate the interaction between basic and clinical science and translational research, further the understanding of the mechanisms that contribute to the development and maintenance of neuropathic pain after SCI, and thus the development of effective mechanisms-based pain treatment strategies.

Pain in spinal cord injury

SUMMARY An important and detrimental effect of spinal cord injury (SCI) is pain, which develops in approximately two-thirds of all SCI patients, while approximately half of SCI patients develop chronic neuropathic pain (NP). Thus far, there is no cure for SCI NP, and oral pharmacological intervention is often inadequate, commonly resulting in a pain reduction of only 20-30%. In this short review, we will present an overview of the important features of SCI pain including taxonomy, epidemiology and classification, as well as a suggested oral pharmacological treatment strategy for SCI NP and the current evidence available from randomized placebo-controlled trials. Considerations and evidence for the nonpharmacological treatment of SCI will be discussed briefly.

Chronic at- and below-level pain after moderate unilateral cervical spinal cord contusion in rats

Chronic neuropathic pain is a significant consequence of spinal cord injury (SCI) that is associated with evoked pain, including allodynia and/or hyperalgesia. Allodynia is defined as a painful response to normally innocuous stimuli, and hyperalgesia occurs when there is an amplified pain response to normally noxious stimuli. We describe a model of a unilateral cervical level (C5) contusion injury where sensory recovery was assessed weekly for 6 weeks in 32 adult, female, Sprague-Dawley rats. Bilateral thermal hyperalgesia and tactile allodynia are detectable in the fore- and hindpaws as early as 7 days post-injury (dpi) and persist for at least 42 days. Paw withdrawal latency in response to a noxious thermal stimulus significantly intra-animal pre-operative values. Change in paw withdrawal latency plateaued at 21 dpi. Interestingly, bilateral forepaw allodynia develops in fewer than 40% of rats as measured by von Frey monofilament testing. Similar results occur in the hindpaws, where bilateral allodynia occurs in 46% of rats with SCI. The contralesional forepaw and both hindpaws of rats showed a slight increase in paw withdrawal threshold to tactile stimuli acutely after SCI, corresponding to ipsilesional forelimb motor deficits that resolve over time. That there is no difference among allodynic and non-allodynic groups in overall spared tissue or specifically of the dorsal column or ventrolateral white matter where ascending sensory tracts reside suggests that SCI-induced pain does not depend solely on the size or extent of the lesion, but that other mechanisms are in play. These observations provide a valid model system for future testing of therapeutic interventions to prevent the onset or to reduce the debilitating effects of chronic neuropathic pain after SCI.