Psycho-social aspects of chronic pain in spinal cord injury

Differences in resting cerebellar and prefrontal cortical blood flow in spinal cord injury-related neuropathic pain: A brief report

Context: Little is understood about differences in resting neural activity among those with spinal cord injury (SCI)-related neuropathic pain. The purpose of this pilot study was to determine resting cerebral blood flow differences in persons with SCI-related neuropathic pain compared to healthy, pain-free able-bodied controls.Methods: Five persons with paraplegia and ten able-bodied participants were included in this study. Resting blood flow, as measured by a continuous arterial spin labeling (ASL) method of fMRI, was analyzed via statistical parametric mapping.Results: Persons with SCI-related neuropathic pain had significantly lower resting blood flow in the cerebellum (Crus I/II), rostral ventromedial medulla and left insular cortex. In contrast, greater resting blood flow occurred in the medial orbitofrontal cortex among those with SCI-related neuropathic pain compared to controls.Conclusion: Differences in resting blood flow were observed among those with SCI-related pain, particularly in regions that may be involved in affective-motivational and cognitive-evaluative aspects of pain. Larger ASL studies in addition to functional connectivity studies using fMRI are needed to clarify unique neural patterns in this complex and often intractable form of pain.

Association of musculoskeletal pain, fear-avoidance factors, and quality of life in active manual wheelchair users with SCI: A pilot study

Objective: Limited evidence examines the association of psychological factors, such as fear of movement and pain catastrophizing, with musculoskeletal pain patterns in active manual wheelchair users with spinal cord injury (SCI). This study investigated the relationship among musculoskeletal pain, fear avoidance factors, quality of life (QoL), activity and duration of injury in individuals with SCI. Design: Cross-sectional correlational. Setting: Community setting. Participants: Twenty-six individuals with SCI (age = 42 ± 14 years, duration manual wheelchair use = 17 ± 13 years, work/school/volunteer hours/week = 31 ± 14; recreation/sports hours/week 10 ± 12). Outcome Measures: Demographics and self-report measures including the Musculoskeletal Pain Survey (MPS), Wheelchair Users Shoulder Pain Index (WUSPI), Tampa Scale of Kinesiophobia (TSK-11), Pain Catastrophizing Scale (PCS), Fear of Pain (FPQ), Subjective Quality of Life Questionnaire (SQoL), and the Social Interaction Inventory (SII). Spearman's rho (ρ) assessed correlation among measures. Results: Strong association existed between age and duration of injury (ρ = 0.66, P < 0.001). SQoL offered a strong, direct correlation with age (ρ = 0.63, P = 0.01), duration of injury (ρ = 0.70, P = 0.001), and strong, inverse relationship with MPStotal (ρ = -0.66, P = 0.003) and MPS shoulder subscore (ρ = -0.64, P = 0.004). WUSPI demonstrated strong, inverse association with self-reported work hours (ρ = -0.52, P = 0.02) and a strong, direct relationship to PCS (ρ = 0.79, P = <0001). PCS demonstrated a strong, inverse relationship to work/school/volunteer hours (ρ = 0.71, P < 0.001) and strong association to TSK-11_total (ρ = 0.61, P = 0.001). A moderate, inverse relationship was identified for recreational/sports hours and FPQ (ρ = 0.48, P = 0.03). Conclusion: This cyclical relationship of musculoskeletal pain, reduced activity, and maladaptive psychological factors allude to interdependence of factors, supporting the multidisciplinary approach to care.

"My friend, the pain": does altered body awareness affect the valence of pain descriptors?

Background: Pain is a marker of bodily status, that despite being aversive under most conditions, may also be perceived as a positive experience. However, how bodily states represent, define, and interpret pain signals, and how these processes might be reflected in common language, remains unclear.

Methods: Qualitative and quantitative methods were used to explore the relationship between bodily awareness, pain reactions, and descriptions. A list of pain-related terms was generated from open-ended interviews with persons with spinal cord injury (SCI), and 138 participants (persons with SCI, health professionals, and a healthy control group) rated each descriptor as representative of pain on a gradated scale. A lexical decision task was used to test the strength of the automatic association of the word “pain” with positive and negative concepts. The behavioral results were related to body awareness, experience of pain, and exposure to pain, by comparing the three groups.

Results: Higher positive and lower negative pain descriptors, as well as slower response times when categorizing pain as an unpleasant experience were found in the SCI group. The effect was not modulated by either the time since the injury or the present pain intensity, but it was linked to the level of subjective bodily awareness. Compared with the SCI group, health experts and non-experts both associated more quickly the word “pain” and unpleasant in the lexical decision task. However, while health professionals attributed positive linguistic qualities to pain, pain was exclusively associated with negative descriptors in healthy controls group.

Conclusions: These findings are discussed in terms of their theoretical and clinical implications. An awareness of bodily signals prominently affects both the sensory and linguistic responses in persons with SCI. Pain should be evaluated more broadly to understand and, by extension, to manage, experiences beyond its adverse side.

MiR-20a Plays a Key Regulatory Role in the Repair of Spinal Cord Dorsal Column Lesion via PDZ-RhoGEF/RhoA/GAP43 Axis in Rat

Spinal cord injury (SCI) causes sensory dysfunctions such as paresthesia, dysesthesia, and chronic neuropathic pain. MiR-20a facilitates the axonal outgrowth of the cortical neurons. However, the role of miR-20a in the axonal outgrowth of primary sensory neurons and spinal cord dorsal column lesion (SDCL) is yet unknown. Therefore, the role of miR-20a post-SDCL was investigated in rat. The NF-200 immunofluorescence staining was applied to observe whether axonal outgrowth of dorsal root ganglion (DRG) neurons could be altered by miR-20a or PDZ-RhoGEF modulation in vitro. The expression of miR-20a was quantized with RT-PCR. Western blotting analyzed the expression of PDZ-RhoGEF/RhoA/GAP43 axis after miR-20a or PDZ-RhoGEF was modulated. The spinal cord sensory conduction function was assessed by somatosensory-evoked potentials and tape removal test. The results demonstrated that the expression of miR-20a decreased in a time-dependent manner post-SDCL. The regulation of miR-20a modulated the axonal growth and the expression of PDZ-RhoGEF/RhoA/GAP43 axis in vitro. The in vivo regulation of miR-20a altered the expression of miR-20a-PDZ-RhoGEF/RhoA/GAP43 axis and promoted the recovery of ascending sensory function post-SDCL. The results indicated that miR-20a/PDZ-RhoGEF/RhoA/GAP43 axis is associated with the pathophysiological process of SDCL. Thus, targeting the miR-20a/PDZ-RhoGEF /RhoA/GAP43 axis served as a novel strategy in promoting the sensory function recovery post-SCI.

Spinal cord injury below-level neuropathic pain relief with dorsal root entry zone microcoagulation performed caudal to level of complete spinal cord transection

OBJECTIVE

Surgically created lesions of the spinal cord dorsal root entry zone (DREZ) to relieve central pain after spinal cord injury (SCI) have historically been performed at and cephalad to, but not below, the level of SCI. This study was initiated to investigate the validity of 3 proposed concepts regarding the DREZ in SCI central pain: 1) The spinal cord DREZ caudal to the level of SCI can be a primary generator of SCI below-level central pain. 2) Neuronal transmission from a DREZ that generates SCI below-level central pain to brain pain centers can be primarily through sympathetic nervous system (SNS) pathways. 3) Perceived SCI below-level central pain follows a unique somatotopic map of DREZ pain-generators.

METHODS

Three unique patients with both intractable SCI below-level central pain and complete spinal cord transection at the level of SCI were identified. All 3 patients had previously undergone surgical intervention to their spinal cords—only cephalad to the level of spinal cord transection—with either DREZ microcoagulation or cyst shunting, in failed attempts to relieve their SCI below-level central pain. Subsequent to these surgeries, DREZ lesioning of the spinal cord solely caudal to the level of complete spinal cord transection was performed using electrical intramedullary guidance. The follow-up period ranged from 1 1/2 to 11 years.

RESULTS

All 3 patients in this study had complete or near-complete relief of all below-level neuropathic pain. The analyzed electrical data confirmed and enhanced a previously proposed somatotopic map of SCI below-level DREZ pain generators.

CONCLUSIONS

The results of this study support the following hypotheses. 1) The spinal cord DREZ caudal to the level of SCI can be a primary generator of SCI below-level central pain. 2) Neuronal transmission from a DREZ that generates SCI below-level central pain to brain pain centers can be primarily through SNS pathways. 3) Perceived SCI below-level central pain follows a unique somatotopic map of DREZ pain generators.

Increased psychological distress among individuals with spinal cord injury is associated with central neuropathic pain rather than the injury characteristics

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

Central neuropathic pain (CNP) is common after spinal cord injury (SCI). The psychological impact of CNP is not clear. Previous studies reported depression and pain catastrophizing among patients with SCI and CNP; however, the lack of control groups prevented discerning whether these were attributed to CNP or to the SCI itself. The aim was to examine the psychological distress among individuals with SCI with and without CNP and controls to evaluate its impact and possible source.

SETTING

Outpatient clinic of a large rehabilitation center.

METHODS

Individuals with SCI and CNP (n = 27) and without CNP (n = 23), and able-bodied controls (n = 20) participated. Data collection included sociodemographics, SCI characteristics, and level of post-traumatic stress disorder (PTSD), anxiety, stress, depression, and pain catastrophizing. The sensory, affective, and cognitive dimensions of CNP were analyzed.

RESULTS

Individuals with SCI and CNP exhibited elevated levels of PTSD, anxiety, stress, depression, and pain catastrophizing compared to the two control groups, which presented similar levels. The psychological variables among the CNP group correlated positively only with the affective dimension of CNP. Neither CNP nor the psychological variables correlated with SCI characteristics.

CONCLUSIONS

Irrespective of CNP intensity, the affective dimension (suffering) is associated with increased psychological distress. Perhaps individual differences in the response to SCI and/or individual traits rather than the mere exposure to SCI may have a role in the emergence of CNP and psychological distress/mood dysfunction. Rehabilitation programs should prioritize stress management and prevention among individuals with SCI and CNP.

In vivo evaluation of microglia activation by intracranial iron overload in central pain after spinal cord injury

Background

Central pain (CP) is a common clinical problem in patients with spinal cord injury (SCI). Recent studies found the pathogenesis of CP was related to the remodeling of the brain. We investigate the roles of iron overload and subsequent microglia activate in the remodeling of the brain after SCI.

Methods

An SCI-induced CP model was established in Sprague-Dawley rats that were randomly assigned to SCI, sham operation, deferoxamine (DFX), minocycline, and nitric oxide synthase inhibitor treatment groups. At 12 weeks, pain behavior and thermal pain threshold were evaluated in each group, and iron transferrin receptor (TfR)1 and ferritin (Fn) mRNA, as well as iron-regulatory protein (IRP)1, FN, lactoferrin, and nuclear factor (NF)-κB protein levels in the rat brains were measured. Microglia proliferation and differentiation and IRP1 expression were evaluated by immunohistochemistry.

Results

Autophagy was observed in rats after SCI, accompanied by reduced latency of thermal pain, increased iron content and IRP1 and NF-κB levels in the hindlimb sensory area, hippocampus, and thalamus, and decreased Fn levels in the hindlimb sensory area. TfR1 mRNA expression was upregulated in activated microglia. Treatment with an iron-chelating agent, or inhibitors of nitric oxide synthase or microglia suppressed microglia proliferation.

Conclusions

SCI may induce intracranial iron overload, which activates microglia via NF-κB signaling. Microglia secrete inflammatory factors that induce neuronal damage and lead to CP. Treatment with an iron-chelating agent or NF-κB or microglia inhibitors can relieve CP resulting from 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.

Effect of oxidative stress induced by intracranial iron overload on central pain after spinal cord injury

BACKGROUND

Central pain (CP) is a common clinical problem in patients with spinal cord injury (SCI). Recent studies found the pathogenesis of CP was related to the remodeling of the brain. We investigate the roles of iron overload and subsequent oxidative stress in the remodeling of the brain after SCI.

METHODS

We established a rat model of central pain after SCI. Rats were divided randomly into four groups: SCI, sham operation, SCI plus deferoxamine (DFX) intervention, and SCI plus nitric oxide synthase (NOS) inhibitor treatment. Pain behavior was observed and thermal pain threshold was measured regularly, and brain levels of iron, transferrin receptor 1 (TfR1), ferritin (Fn), and lactoferrin (Lf), were detected in the different groups 12 weeks after establishment of the model.

RESULTS

Rats demonstrated self-biting behavior after SCI. Furthermore, the latent period of thermal pain was reduced and iron levels in the hind limb sensory area, hippocampus, and thalamus increased after SCI. Iron-regulatory protein (IRP) 1 levels increased in the hind limb sensory area, while Fn levels decreased. TfR1 mRNA levels were also increased and oxidative stress was activated. Oxidative stress could be inhibited by ferric iron chelators and NOS inhibitors.

CONCLUSIONS

SCI may cause intracranial iron overload through the NOS-iron-responsive element/IRP pathway, resulting in central pain mediated by the oxidative stress response. Iron chelators and oxidative stress inhibitors can effectively relieve SCI-associated central pain.

Surgical Management of Civilian Gunshot-Induced Spinal Cord Injury: Is It Overutilized?

STUDY DESIGN

Retrospective chart review.

OBJECTIVE

Assess appropriate utilization of surgery for civilian gunshot-induced spinal cord injuries (CGSWSCI) according to literature standards in a large cohort.

SUMMARY OF BACKGROUND DATA

CGSWSCI are mechanically stable injuries that rarely require surgery. Nonetheless, we continue to see high numbers of these patients undergo surgical treatment. This study compares indications for surgeries performed in a large cohort of CGSWSCI patients to established indications for surgical management of such injuries. The rate of over-utilization of surgical management was calculated.

METHODS

Four hundred eighty-nine CGSWSCI patients transferred for rehabilitation to our institution between 2000 and 2014 were identified. Retrospective chart review was performed to identify patients who underwent initial surgical treatment, the specific surgeries performed, and indications given. We assessed appropriateness of surgery according to literature standards. Patients treated surgically were followed to assess for complications and the need for additional intervention and compared to nonsurgical patients. Secondarily, visual analog scale pain scores (0-10) and patient perceived improvement were compared between surgical and nonsurgical patients after telephone survey of both groups.

RESULTS

Of 489 patients, 91 (18%) underwent initial surgery. Of 91 surgeries, 69 (75%) were not indicated by literature standards. Five of 91 (5.5%) of initially operated patients required a secondary surgery compared with two of 398 (0.5%) of the nonoperative group (P = 0.003). Over-utilization rate of the entire cohort was 14.1%. No difference was seen for pain scores or patient perceived improvement between operative and nonoperative patients.

CONCLUSION

We report a high overutilization rate (14%) of surgery for CGSWSCI in our cohort. Surgical management was associated with higher infection and secondary surgery rates compared to nonsurgical management. Surgery done without a clear, demonstrable benefit poses unnecessary risk to patients and accumulates unwarranted healthcare costs.

LEVEL OF EVIDENCE

3.

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.

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.

The impact of pain on spiritual well-being in people with a spinal cord injury

STUDY DESIGN

The study uses a cross-sectional, group comparison, questionnaire-based design.

OBJECTIVES

To determine whether spinal cord injury and pain have an impact on spiritual well-being and whether there is an association between spiritual well-being and measures of pain and psychological function.

SETTING

University teaching hospital in Sydney, New South Wales, Australia.

METHODS

Questionnaires evaluating pain, psychological and spiritual well-being were administered to a group of people with a spinal cord injury (n=53) and a group without spinal cord injury (n=37). Spiritual well-being was assessed using the Functional Assessment of Chronic Illness and Therapy - Spirituality Extended Scale (FACIT-Sp-Ex). Pain and psychological function were also assessed using standard, validated measures of pain intensity, pain interference, mood and cognition.

RESULTS

Levels of spiritual well-being in people with a spinal cord injury were significantly lower when compared with people without a spinal cord injury. In addition, there was a moderate but significant negative correlation between spiritual well-being and pain intensity. There was also a strong and significant negative correlation between depression and spiritual well-being and a strong and significant positive correlation between spiritual well-being and both pain self-efficacy and satisfaction with life.

CONCLUSION

Consequences of a spinal cord injury include increased levels of spiritual distress, which is associated, with higher levels of pain and depression and lower levels of pain self-efficacy and satisfaction with life. These findings indicate the importance of addressing spiritual well-being as an important component in the long-term rehabilitation of any person following spinal cord injury.

SPONSORSHIP

This study was supported by grant funding from the Australian and New Zealand College of Anaesthetists, and the National Health and Medical Research Council of Australia.

Somatosensory phenotype is associated with thalamic metabolites and pain intensity after spinal cord injury

Neuropathic pain is one of the most difficult consequences of spinal cord injury (SCI). The clinical correlates of the underlying mechanisms responsible for neuropathic pain are not well understood, although methods such as quantitative somatosensory testing (QST) or brain imaging have been used to further a mechanism-based understanding of pain. Our previous SCI study demonstrated a significantly lower glutamate-glutamine/myo-inositol ratio (Glx/Ins) in the anterior cingulate cortex in persons with severe neuropathic pain compared with those with less severe neuropathic pain or pain-free, able-bodied controls, suggesting that a combination of decreased glutamatergic metabolism and glial activation may contribute to the development of severe neuropathic pain after SCI. The present study aimed to determine the relationships between somatosensory function below the level of injury and low thalamic Glx/Ins in persons with intense neuropathic pain after SCI. Participants underwent QST and a 3 Tesla proton magnetic resonance spectroscopy. A cluster analysis including SCI participants resulted in 1 group (n = 19) with significantly (P < 0.001) greater pain intensity (6.43 ± 1.63; high neuropathic pain [HNP], and lower Glx/Ins [1.22 ± 0.16]) and another group (n = 35) with lower pain intensity ratings (1.59 ± 1.52, low neuropathic pain [LNP], and higher Glx/Ins [1.47 ± 0.26]). After correcting for age, QST indicated significantly greater somatosensory function in the HNP group compared with the LNP group. Our results are consistent with research suggesting that damage to, but not abolition of, the spinothalamic tract contributes to development of neuropathic pain after SCI and that secondary inflammatory processes may amplify residual spinothalamic tract signals by facilitation, disinhibition, or sensitization.

Classifying and predicting endurance outcomes of α2-adrenergic agonist intervention in spinal cord injury

Spinal cord injury (SCI) is a traumatic condition that can lead to both functional and neuromuscular impairments. Spasticity in the muscles surrounding the ankle joint caused by hypertonia is often reported as a complication. We investigated whether a pharmacological intervention using Tizanidine, an anti-spastic medication acting as an α2-adrenergic agonist, could lead to improvements in walking endurance. We placed subjects on a 4-week program and measured the change in clinical measures of walking speed, endurance, and mobility. We used growth mixture modeling (GMM) to class subjects into groups based on recovery patterns. Two classes of recovery were found by GMM: high and low functioning. Radom coefficient regression (RCR) was then used to identify significant changes over time. Statistically significant improvements in walking endurance were shown for the high functioning group. However, a small number of subjects in the high functioning group showed improvement greater than the smallest real difference (SRD), which indicates a clinical significance as well. We also investigated the extent to which these recovery patterns can be predicted using baseline measures. Baseline walking endurance was found to be a robust predictor of recovery in walking endurance. Subjects that began the intervention with already higher endurance showed a greater chance of improvement in endurance over time. This information could potentially be used as a fast and reliable assessment tool for clinicians to predict which patient can benefit the most from this intervention prior to prescribing the medication, and thus optimizing cost and resources. Our findings demonstrate that these techniques can be used to characterize and predict the progress of changes to functional impairments due to various types of intervention.

Longitudinal interactions of pain and posttraumatic stress disorder symptoms in U.S. Military service members following blast exposure

Military personnel returning from conflicts in Iraq and Afghanistan often endorse pain and posttraumatic stress disorder (PTSD) symptoms, either separately or concurrently. Associations between pain and PTSD symptoms may be further complicated by blast exposure from explosive munitions. Although many studies have reported on the prevalence and disability associated with polytraumatic injuries following combat, less is known about symptom maintenance over time. Accordingly, this study examined longitudinal interactive models of co-occurring pain and PTSD symptoms in a sample of 209 military personnel (mean age = 27.4 years, standard deviation = 7.6) who experienced combat-related blast exposure. Autoregressive cross-lagged analysis examined longitudinal associations between self-reported pain and PTSD symptoms over a 1-year period. The best-fitting covariate model indicated that pain and PTSD were significantly associated with one another across all assessment periods, χ² (3) = 3.66, P = .30, Tucker-Lewis index = .98, comparative fit index = 1.00, root mean squared error of approximation = .03. PTSD symptoms had a particularly strong influence on subsequent pain symptoms. The relationship between pain and PTSD symptoms is related to older age, race, and traumatic brain injury characteristics. Results further the understanding of complex injuries among military personnel and highlight the need for comprehensive assessment and rehabilitation efforts addressing the interdependence of pain and co-occurring mental health conditions.

PERSPECTIVE

This longitudinal study demonstrates that pain and PTSD symptoms strongly influence one another and interact across time. These findings have the potential to inform the integrative assessment and treatment of military personnel with polytrauma injuries and who are at risk for persistent deployment-related disorders.

Thermal hyperalgesia assessment for rats after spinal cord injury: developing a valid and useful pain index

BACKGROUND CONTEXT

Ongoing research to understand the mechanism behind pain is heavily dependent on animal testing. However, unlike humans, animal subjects cannot directly communicate with researchers to express the degree of pain they are experiencing. Therefore, measuring the presence of pain in animal studies is based on behavioral tests. The use of arbitrary values for determining the presence of pain in animal studies is an oversimplification of a complex and cortically dependent process.

PURPOSE

The purpose of the present study was to identify a statistically supported latency time indicator that can be used as an accurate index for hyperalgesia to thermal stimuli in Sprague-Dawley rats subjected to T9 contusive spinal cord injury (SCI).

STUDY DESIGN

A statistical analysis of latency of withdrawal from stimulus-mediated spinal reflex in 979 Sprague-Dawley rats that had been subjected to a T9 contusive SCI was performed.

METHODS

This is a retrospective review of a large research database derived from a series of studies performed evaluating thermal hyperalgesia in rats after SCI. Sprague-Dawley rats underwent a T9 contusive SCI and were tested for withdrawal latency from a heat stimulus. Assessment was done preinjury and on Postinjury Days 21, 28, 35, and 42 of the chronic phase of injury via a plantar withdrawal test.

RESULTS

The baseline test results of the 979 rats showed a significant resemblance to the normal distribution. The observed change in withdrawal showed mean latency drops of 0.42 second (standard error of the mean [SEM], 0.18; p=.026), 0.57 second (SEM, 0.19; p=.004), 0.63 second (SEM, 0.19; p=.002), and 0.69 second (SEM, 0.19; p=.0003). The standard deviation from the mean at all four postsurgical assessments was between 2.8 and 2.9 seconds.

CONCLUSIONS

Interpretation of withdrawal latency times as a marker for thermal hyperalgesia must be based on an appreciation for the normal distribution of pain scores. Recognizing that withdrawal latency is normally distributed both before and after injury allows for rational assignment of animals to groups designated as hyperalgesic and nonhyperalgesic. Two point nine seconds faster than the mean latency time is a statistically reliable indicator of thermal hyperalgesia in Sprague-Dawley rats subjected to contusive SCI. Repeated testing of animals to establish the presence or absence of thermal hyperalgesia beyond 21 days is not necessary in the absence of intervention.

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.

SNAP25 ameliorates sensory deficit in rats with spinal cord transection

Spinal cord injury causes sensory loss below the level of lesion. Synaptosomal-associated protein 25 (SNAP25) is a t-SNARE protein essential for exocytosis and neurotransmitter release, but its role in sensory functional recovery has not been determined. The aim of the present study is therefore to investigate whether SNAP25 can promote sensory recovery. By 2D proteomics, we found a downregulation of SNAP25 and then constructed two lentiviral vectors, Lv-exSNAP25 and Lv-shSNAP25, which allows efficient and stable RNAi-mediated silencing of endogenous SNAP25. Overexpression of SNAP25 enhanced neurite outgrowth in vitro and behavior response to thermal and mechanical stimuli in vivo, while the silencing of SNAP25 had the opposite effect. These results suggest that SNAP25 plays a crucial role in sensory functional recovery following spinal cord injury (SCI). Our study therefore provides a novel target for the management of SCI for sensory dysfunction.

Neuropathic pain in patients with spinal cord injury: report of 213 patients

Objective Management of neuropathic pain following spinal cord injury (SCI) can be a frustrating experience for patients since it poses a therapeutic challenge. In this article the authors describe the clinical characteristics of a group of patients with pain after spinal cord injury. Methods In this retrospective study, 213 patients with SCI and neuropathic pain were assessed. We analyzed clinical characteristics, treatment options, and pain intensity for these patients. Results The main cause of SCI was spine trauma, which occurred in 169 patients, followed by tumors and infection. Complete lesions were verified in 144 patients. In our study, patients with traumatic SCI and partial lesions seem to be presented with more intense pain; however, this was not statistically significant. Conclusions Neuropathic pain is a common complaint in patients with SCI and presents a treatment challenge. Knowledge of the clinical characteristics of this group of patients may help determine the best approach to intervention.

Effects of nicotine on spinal cord injury pain: a randomized, double-blind, placebo controlled crossover trial

BACKGROUND

One factor affecting spinal cord injury (SCI)-related pain may be nicotine. Case reports have described a worsening of neuropathic pain from smoking and relief from abstinence. Neurobiological correlates also implicate the potential effect of nicotine on SCI-related pain.

METHOD

The current study employed a randomized, placebo-controlled crossover design to examine the effect of nicotine exposure on subtypes of SCI-related pain among smokers and nonsmokers.

RESULTS

Whereas nonsmokers with SCI showed a reduction in mixed forms of pain following nicotine exposure, smokers with SCI showed a converse increase in pain with regard to both mixed and neuropathic forms of pain. The exacerbation of pain in chronic nicotine or tobacco users may not only elucidate possible pain mechanisms but may also be of use in smoking cessation counseling among those with SCI.

Promoting optimal functioning in spinal cord injury: the role of rehabilitation psychology

Comprehensive treatment and rehabilitation includes attention to the psychological needs of individuals with SCI and their families. This chapter is designed to familiarize neurologists and other practitioners with psychological issues and care in SCI. While psychologists play a key role, attention to psychosocial health is a responsibility shared by all members of the rehabilitation team, beginning with the patient and family, and including clinicians who are not formally identified as mental health providers. Treatment planning for a person with SCI begins with a thorough assessment of the cognitive, emotional, personality, and social factors that influence functioning and rehabilitation. Rehabilitation psychologists use a mixture of assessment tools, including clinical interviews, behavioral observations, and a wide range of standardized test instruments. Psychological interventions can involve direct intervention with the patient, in individual, family or group-based therapies. Other psychological strategies involve assistance through less direct methods - consultation and training to other rehabilitation team members or facilitating peer role-modeling and support groups. The chapter provides an overview of core clinical issues (emotional responses, substance use, pain, cognitive deficits, sexuality and vocational rehabilitation), delineates the process of psychological assessment and intervention, and provides guidance on incorporation of rehabilitation psychology into SCI rehabilitation.

Coexisting mechanical hypersensitivity and anxiety in a rat model of spinal cord injury and the effect of pregabalin, morphine, and midazolam treatment

Background and purpose

Spinal cord injury (SCI) has detrimental consequences that include chronic neuropathic pain, which is seen in 40-50% of patients, and symptoms of anxiety and depression, which affect 13-45% of SCI patients. The coexistence of pain, anxiety, and depression is known from other neuropathic pain conditions, but the relationship between these symptoms is not clear and has not been investigated in a preclinical model of SCI so far.

The aim of this study was to investigate anxiety-like behavior and at-level mechanical hypersensitivity following experimental spinal cord contusion (SCC) in female Sprague-Dawley rats, and the effects of analgesic and anxiolytic drugs.

Methods

Mechanical sensitivity and elevated plus maze (EPM) behavior were measured pre- and postinjury in SCC and sham animals. Pregabalin 30 mg/kg, morphine 3 mg/kg, midazolam 0.5 mg/kg, and 0.9% NaCl were evaluated in a randomly allocated, blinded balanced design.

Results

SCC animals developed persistent at-level mechanical hypersensitivity and decreased open arm activity in the EPM, which indicates an anxiety-like state. Pregabalin, a dual-acting analgesic and anxiolytic drug reduced both hypersensitivity and anxiety-like behavior, while the analgesic drug morphine only reduced hypersensitivity. The anxiolytic drug midazolam in the dose used had no effect on either parameter.

Conclusions

SCC animals developed long lasting coexisting at-level mechanical hypersensitivity and anxiety-like behavior, but there was no evidence to support a causal relationship between pain and anxiety following SCI.

Implications

The findings that at-level mechanical hypersensitivity and anxiety-like behavior develops concomitantly in the spinal cord contusion models and that both symptoms is persistent provide basis for further investigation of the mechanisms and connection behind these two clinically relevant symptoms after injury to the central nervous system.

The animal model of spinal cord injury as an experimental pain model

Pain, which remains largely unsolved, is one of the most crucial problems for spinal cord injury patients. Due to sensory problems, as well as motor dysfunctions, spinal cord injury research has proven to be complex and difficult. Furthermore, many types of pain are associated with spinal cord injury, such as neuropathic, visceral, and musculoskeletal pain. Many animal models of spinal cord injury exist to emulate clinical situations, which could help to determine common mechanisms of pathology. However, results can be easily misunderstood and falsely interpreted. Therefore, it is important to fully understand the symptoms of human spinal cord injury, as well as the various spinal cord injury models and the possible pathologies. The present paper summarizes results from animal models of spinal cord injury, as well as the most effective use of these models.

Peripheral and central sensitization in remote spinal cord regions contribute to central neuropathic pain after spinal cord injury

Central neuropathic pain (CNP) developing after spinal cord injury (SCI) is described by the region affected: above-level, at-level and below-level pain occurs in dermatomes rostral, at/near, or below the SCI level, respectively. People with SCI and rodent models of SCI develop above-level pain characterized by mechanical allodynia and thermal hyperalgesia. Mechanisms underlying this pain are unknown and the goals of this study were to elucidate components contributing to the generation of above-level CNP. Following a thoracic (T10) contusion, forelimb nociceptors had enhanced spontaneous activity and were sensitized to mechanical and thermal stimulation of the forepaws 35 days post-injury. Cervical dorsal horn neurons showed enhanced responses to non-noxious and noxious mechanical stimulation as well as thermal stimulation of receptive fields. Immunostaining dorsal root ganglion (DRG) cells and cord segments with activating transcription factor 3 (ATF3, a marker for neuronal injury) ruled out neuronal damage as a cause for above-level sensitization since few C8 DRG cells expressed AFT3 and cervical cord segments had few to no ATF3-labeled cells. Finally, activated microglia and astrocytes were present in thoracic and cervical cord at 35 days post-SCI, indicating a rostral spread of glial activation from the injury site. Based on these data, we conclude that peripheral and central sensitization as well as reactive glia in the uninjured cervical cord contribute to CNP. We hypothesize that reactive glia in the cervical cord release pro-inflammatory substances which drive chronic CNP. Thus a complex cascade of events spanning many cord segments underlies above-level CNP.

Chronic constriction injury induces aquaporin-2 expression in the dorsal root ganglia of rats

Aquaporins are a family of water channel proteins involved in water homeostasis in several tissues. Current knowledge of aquaporin expression in the nervous system is very limited. Therefore the first aim of this study was to assess, by immunohistochemistry and immunoblotting analysis, the presence and localization of aquaporin-2 in the spinal cord and dorsal root ganglia of naïve adult rats. In addition, we evaluated aquaporin-2 expression in response to chronic constriction injury of the sciatic nerve, a model of neuropathic pain. Our results showed that aquaporin-2 expression was not detectable either in the spinal cord or the dorsal root ganglia of naïve rats. However, we showed for the first time an increase of aquaporin-2 expression in response to chronic constriction injury treatment in small-diameter dorsal root ganglia neurons but no expression in the lumbar spinal cord. These data support the hypothesis that aquaporin-2 expression is involved in inflammatory neuropathic nerve injuries, although its precise role remains to be determined.

What are the risk factors of occurence and chronicity of neuropathic pain in spinal cord injury patients?

OBJECTIVE

Analyze the epidemiological data on neuropathic pain in spinal cord injury patients and determine the risk factors for its occurrence and chronicity.

METHOD

Review and analysis of the literature.

RESULTS

Epidemiological data report that 40% of spinal cord injury (SCI) patients suffer from neuropathic pain and 40% of these patients report an intense neuropathic pain. Some factors do not seem to be predictive for the onset of neuropathic pain: the level of injury, complete or incomplete injury, the existence of an initial surgery, sex. However, old age at the time of injury, bullet injury as the cause of trauma, early onset of pain in the weeks following the injury, their initial nature, intensity and continuous pain, as well as associated symptoms all appear to be negative prognostic factors.

CONCLUSION

Neuropathic pain in SCI patients is a major issue, its determining factors still need to be evaluated properly by refining the epidemiological data.

Mechanisms of chronic central neuropathic pain after spinal cord injury

Not all spinal contusions result in mechanical allodynia, in which non-noxious stimuli become noxious. The studies presented use the NYU impactor at 12.5 mm drop or the Infinite Horizons Impactor (150 kdyn, 1 s dwell) devices to model spinal cord injury (SCI). Both of these devices and injury parameters, if done correctly, will result in animals with above level (forelimb), at level (trunk) and below level (hindlimb) mechanical allodynia that model the changes in evoked somatosensation experienced by the majority of people with SCI. The sections are as follows: 1) Mechanisms of remote microglial activation and pain signaling in "below-level" central pain 2) Intracellular signaling mechanisms in central sensitization in "at-level" pain 3) Peripheral sensitization contributes to "above level" injury pain following spinal cord injury and 4) Role of reactive oxygen species in central sensitization in regional neuropathic pain following SCI. To summarize, differential regional mechanisms contribute to the regional chronic pain states. We propose the importance of understanding the mechanisms in the differential regional pain syndromes after SCI in the chronic condition. Targeting regional mechanisms will be of enormous benefit to the SCI population that suffer chronic pain, and will contribute to better treatment strategies for other chronic pain syndromes.

Locomotor dysfunction and pain: the scylla and charybdis of fiber sprouting after spinal cord injury

Injury to the spinal cord (SCI) can produce a constellation of problems including chronic pain, autonomic dysreflexia, and motor dysfunction. Neuroplasticity in the form of fiber sprouting or the lack thereof is an important phenomenon that can contribute to the deleterious effects of SCI. Aberrant sprouting of primary afferent fibers and synaptogenesis within incorrect dorsal horn laminae leads to the development and maintenance of chronic pain as well as autonomic dysreflexia. At the same time, interruption of connections between supraspinal motor control centers and spinal cord output cells, due to lack of successful regenerative sprouting of injured descending fiber tracts, contributes to motor deficits. Similarities in the molecular control of axonal growth of motor and sensory fibers have made the development of cogent therapies difficult. In this study, we discuss recent findings related to the degradation of inhibitory barriers and promotion of sprouting of motor fibers as a strategy for the restoration of motor function and note that this may induce primary afferent fiber sprouting that can contribute to chronic pain. We highlight the importance of careful attentiveness to off-target molecular- and circuit-level modulation of nociceptive processing while moving forward with the development of therapies that will restore motor function after SCI.

Reports from spinal cord injury patients: eight months after the 2003 earthquake in Bam, Iran

OBJECTIVE

The World Health Organization defines disaster as a sudden ecologic phenomenon of sufficient magnitude to require external assistance. On December 26, 2003, the Bam earthquake left more than 200 spinal cord injury (SCI) patients. Our study of these SCI patients and the rehabilitation of disabled persons in Bam may assist in the organization of rehabilitation programs during future disasters.

DESIGN

Eight months after the disaster, we planned to visit the SCI patients in Bam. We visited 61 patients in Bam, Baravat, and surrounding villages. We completed a questionnaire during our visit.

RESULTS

The patients' mean age was 31.9 +/- 9.6 yrs. Twenty-nine (53.7%) patients were female, and 25 (46.3%) were male. Fifty-two (96.3%) patients had pain syndromes, which had started from 3 days to 8 mos after injury. Thirty-three (61%) patients used clean intermittent catheterization, and 29 (53.7%) did not have bowel programs. Nineteen (35.2%) patients had pressure sores.

CONCLUSIONS

All aspects of disasters should be considered seriously by all countries. The special needs of people with disabilities during and long after any disaster are important. The impact of disasters on disabled people is magnified because of their condition, so special attention must be paid to this group.

Self-inflicted finger injury in individuals with spinal cord injury: an analysis of 5 cases

OBJECTIVE

To describe the occurrence of finger autophagia in 5 persons with traumatic spinal cord injury and to present a discussion of putative causes and potential treatments.

BACKGROUND

Minor self-mutilating actions, such as nail biting and hair pulling, are common in humans and usually benign. In some circumstances, these behaviors are associated with obsessive-compulsive personality traits. In humans, self-injurious biting behaviors are well described in the setting of mental retardation and psychosis and in persons with Lesch-Nyhan syndrome. Rare cases of human autophagia in persons with intact cognition have been reported, most commonly in the setting of acquired nervous system lesions. After spinal cord injury, it has been suggested that this behavior constitutes a human variant of animal autotomy and a response to neuropathic pain.

DESIGN

Case presentation narrative.

MAIN OUTCOME MEASURES

Photographic and radiological study, administration of Yale-Brown Obsessive-Compulsive Scale (YBOCS).

FINDINGS

In 5 patients with complete tetraplegia, pain in the hands was present in only one instance. The severity of autoamputation varied from minor to extreme. In all cases, damage was confined to analgesic body parts. In 3 cases, autophagia behavior was discovered in progress. Treatments included pharmacotherapy, counseling, and behavioral therapy, with mixed results. All patients were intelligent, willing to discuss their issues, and able to identify conditions of stress and isolation in their lives. Mild preinjury obsessive-compulsive behaviors, such as nail biting, were universal. On the YBOCS, only 1 patient scored in a range indicative of mild obsessive-compulsive symptomatology.

CONCLUSIONS

This group exhibited heterogeneous medical, social, and cultural characteristics. A link between pain and self-injurious behavior could not be demonstrated. This behavior may be viewed as an extreme variant of nail biting, with potential ominous complications. Treatment strategies have been employed with mixed results.

A case report of firearm bullet settling into the thoracic spinal canal without causing neurological deficit or vertebral bone destruction

OBJECTIVE

The main objective of this study was to present a case of gunshot injury in which a bullet particle settled into the inferior-thoracic epidural canal, which was neurologically intact, without causing any vertebral bone destruction. There has been no previous report in the literature regarding a foreign body settling into the vertebral canal following gunshot injury without causing any bony destruction.

CASE REPORT

A 40-year-old male patient was hospitalized in emergency service with the complaints of severe pain in his back and both legs secondary to a gunshot wound. The entrance wound of the traversing projectile was located at the level of the tenth costa at the inferior of the right scapula. Neurological examination revealed no motor deficit. His lung X-ray was normal at radiological examination. Direct radiograph determined a bullet nucleus on the medium line at thoracolumbar level T-12. Intracanalicular bullet nucleus was found at posterior epidural at the T-12 level on thoracic CT, myelography and CT myelography. No vertebral bone destruction was seen in the direct radiograph studies and serial CT. T12 total laminectomy was performed and epidural foreign body removed. The patient, whose pains ameliorated during the postoperative process, was discharged without any neurological deficit.

CONCLUSION

We prefer removal of firearm particles settling into the spinal canal in view of possible later complications such as infection and the toxic effect of the metallic particles, unless there appears any risk of neurological detriment to the patient.

Pain following spinal cord injury

Pain is one of the most common, severe, and treatment-resistant complications that follows SCI. Recent years have seen a surge of research on methods for assessing and treating spinal cord injury pain. In this article, pain after SCI is reviewed in terms of nature, scope, assessment techniques, and treatment strategies.

Spinal Cord Injury Pain: The Influence of Psychologic Factors and Impact on Quality of Life

OBJECTIVES

To examine chronic pain prevalence in a spinal cord injury (SCI) population, and to determine the influence of psychologic factors on SCI pain and impact of SCI pain on quality of life.

METHODS

Five hundred seventy-five persons with SCI were asked to participate in the study. Demographic, SCI, and pain characteristics were obtained. The Chronic Pain Grade, anger items of the Profile of Mood States, Illness Cognition Questionnaire, Pain Coping and Cognition List, and Patient Health Questionnaire were used. General health and well-being were assessed with 0-10 scales. The influence of psychologic factors was assessed with regression analyses controlling for person and injury characteristics and pain intensity.

RESULTS

Response rate was 49%. SCI pain prevalence was high (77.1%). More internal pain control and coping, less catastrophizing, higher level of lesion, and nontraumatic SCI cause were associated with less pain intensity. More pain was associated with higher pain-related disability. Lower catastrophizing was related to better health. Less SCI helplessness and catastrophizing, greater SCI acceptance and lower anger levels were related to higher well-being. Higher levels of SCI helplessness, catastrophizing, and anger were related to higher depression levels. Pain intensity showed no independent relationships with health, well-being, and depression in the regression analyses.

DISCUSSION

Chronic SCI pain and quality of life were both largely associated with several psychologic factors of which pain catastrophizing and SCI helplessness were most important. Psychologic intervention programs may be useful for persons suffering from chronic SCI pain to improve their quality of life.

Treatments for chronic pain in persons with spinal cord injury: A survey study

BACKGROUND/OBJECTIVE

To determine the degree and duration of pain relief provided by specific pain treatments used by individuals with spinal cord injury (SCI) who have chronic pain.

DESIGN

Postal survey.

SETTING

Community.

PARTICIPANTS

Participants were 117 individuals who had traumatic SCI, were 18 years of age or older, and reported a chronic pain problem.

MAIN OUTCOME MEASURES

Questions assessing current or past use of 26 different pain treatments, the amount of relief each treatment provided, and the length of time that any pain relief usually lasts.

RESULTS

The medications tried most often were nonsteroidal anti-inflammatory drugs (tried by 71%) and acetaminophen (tried by 70%); these medications were still being used by more than one half of the patients who had tried them. Opioids produced the greatest degree of pain relief on average (mean, 6.27 +/- 3.05 [SD] on a 0-10 scale, with 0 = no relief and 10 = complete relief) but were unlikely to be continued by those who tried them. Although 38% of respondents with pain had tried gabapentin, only 17% were still using it, and average pain relief was only moderate (mean, 3.32 +/- 3.03 on the 0-10 relief scale). Seventy-three percent of the respondents had tried at least 1 of 7 alternative pain treatments, and the most frequently tried were massage, marijuana, and acupuncture. The most relief was provided by massage (mean, 6.05 +/- 2.47] on the 0-10 relief scale) and marijuana (mean, 6.62 +/- 2.54 on the 0-10 relief scale). The relief from the various treatments, including most medications, tended to last only minutes or hours; however, pain relief from alternative treatments such as massage, acupuncture, and hypnosis was reported to last for days in 25% to 33% of those who tried these treatments.

CONCLUSIONS

Many patients are not finding adequate pain relief from commonly prescribed medications. Alternative therapies should be considered as additional treatment options in this population.

Transcriptional profiling of spinal cord injury-induced central neuropathic pain

Central neuropathic pain (CNP) is an important problem following spinal cord injury (SCI), because it severely affects the quality of life of SCI patients. As in the patient population, the majority of rats develop significant allodynia (CNP rats) after moderate SCI. However, about 10% of SCI rats do not develop allodynia, or develop significantly less allodynia than CNP rats (non-CNP rats). To identify transcriptional changes underlying CNP development after SCI, we used Affymetrix DNA microarrays and RNAs extracted from the spinal cords of CNP and non-CNP rats. DNA microarry analysis showed significantly increased expression of a number of genes associated with inflammation and astrocytic activation in the spinal cords of rats that developed CNP. For example, mRNA levels of glial fibrilary acidic protein (GFAP) and Aquaporin 4 (AQP4) significantly increased in CNP rats. We also found that GFAP, S100beta and AQP4 protein elevation persisted for at least 9 months throughout contused spinal cords, consistent with the chronic nature of CNP. Thus, we hypothesize that CNP development results, in part, from dysfunctional, chronically "over-activated" astrocytes. Although, it has been shown that activated astrocytes are associated with peripheral neuropathic pain, this has not previously been demonstrated in CNP after SCI.