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.

The CanPain SCI Clinical Practice Guidelines for Rehabilitation Management of Neuropathic Pain after Spinal Cord: introduction, methodology and recommendation overview.

STUDY DESIGN: Clinical practice guidelines. OBJECTIVES: The objective was to develop the first Canadian clinical practice guidelines for the management of neuropathic pain in people with spinal cord injury (SCI). SETTING: The guidelines are relevant for inpatient and outpatient SCI rehabilitation settings in Canada. METHODS: The guidelines were developed in accordance with the Appraisal of Guidelines for Research and Evaluation II tool. A Steering Committee and Working Group reviewed the relevant evidence on neuropathic pain management (encompassing screening and diagnosis, treatment and models of care) after SCI. The quality of evidence was scored using Grading of Recommendations Assessment, Development and Evaluation (GRADE). A consensus process was followed to achieve agreement on recommendations and clinical considerations. RESULTS: The Working Group developed 12 recommendations for screening and diagnosis, 12 recommendations for treatment and 5 recommendations for models of care. Important clinical considerations accompany each recommendation. CONCLUSIONS: The Working Group recommendations for the management of neuropathic pain after SCI should be used to inform practice.

The CanPain SCI Clinical Practice Guidelines for Rehabilitation Management of Neuropathic Pain after Spinal Cord: Recommendations for treatment.

STUDY DESIGN: Clinical practice guidelines. OBJECTIVES: To develop the first Canadian clinical practice guidelines for treatment of neuropathic pain in people with spinal cord injury (SCI). SETTING: The guidelines are relevant for inpatient and outpatient SCI rehabilitation settings in Canada. METHODS: The CanPainSCI Working Group reviewed the evidence for different treatment options and achieved consensus. The Working Group then developed clinical considerations for each recommendation. Recommendations for research are also included. RESULTS: Twelve recommendations were developed for the management of neuropathic pain after SCI. The recommendations address both pharmacologic and nonpharmacologic treatment modalities. CONCLUSIONS: An expert Working Group developed recommendations for the treatment of neuropathic pain after SCI that should be used to inform practice.

The CanPain SCI Clinical Practice Guideline for Rehabilitation Management of Neuropathic Pain after Spinal Cord: recommendations for model systems of care.

STUDY DESIGN: Clinical practice guidelines. OBJECTIVES: The project objectives were to develop the first Canadian recommendations on a model of care for the management of at- and below-level neuropathic pain in people with spinal cord injury (SCI). SETTING: The guidelines are relevant for inpatient and outpatient SCI rehabilitation settings in Canada. METHODS: On the basis of a review of the Accreditation Canada standards, the Steering Committee developed questions to guide the CanPainSCI Working Group when developing the recommendations. The Working Group agreed on recommendations through a consensus process. RESULTS: The Working Group developed five recommendations for the organization of neuropathic pain rehabilitation care in people with SCI. CONCLUSIONS: The Working Group recommendations for a model of care for at- and below-level neuropathic pain after SCI should be used to inform clinical practice.

The CanPain SCI Clinical Practice Guidelines for Rehabilitation Management of Neuropathic Pain after Spinal Cord: screening and diagnosis recommendations.

STUDY DESIGN: Clinical practice guidelines. OBJECTIVES: To develop the first Canadian clinical practice guidelines for screening and diagnosis of neuropathic pain in people with spinal cord injury (SCI). SETTING: The guidelines are relevant for inpatient and outpatient SCI rehabilitation settings in Canada. METHODS: The CanPainSCI Working Group reviewed evidence to address clinical questions regarding screening and diagnosis of neuropathic pain after SCI. A consensus process was followed to achieve agreement on recommendations and clinical considerations. RESULTS: Twelve recommendations, based on expert consensus, were developed for the screening and diagnosis of neuropathic pain after SCI. The recommendations address methods for assessment, documentation tools, team member accountability, frequency of screening and considerations for diagnostic investigation. Important clinical considerations accompany each recommendation. CONCLUSIONS: The expert Working Group developed recommendations for the screening and diagnosis of neuropathic pain after SCI that should be used to inform practice.

The International Spinal Cord Injury Pain Extended Data Set (Version 1.0).

OBJECTIVES: The objective of this study was to develop the International Spinal Cord Injury Pain Extended Data Set (ISCIPEDS) with the purpose of guiding the assessment and treatment of pain after spinal cord injury (SCI). SETTING: International. METHODS: The ISCIPEDS was reviewed by members of the International SCI Data Sets Committee, the International Spinal Cord Society Executive and Scientific Committees, American Spinal Injury Association and American Pain Society Boards, and the Neuropathic Pain Special Interest Group of the International Association for the Study of Pain, individual reviewers and societies. RESULTS: The working group recommended four assessment domains for the ISCIPEDS: (i) Pain symptoms including variables related to pain type, temporal course, severity, unpleasantness, tolerability of pain and questionnaires assessing pain type and symptom severity; (ii) Sensory signs to detect and quantify sensory abnormalities commonly associated with neuropathic pain, including dynamic mechanical and thermal allodynia, and hyperalgesia; (iii) Treatments (ongoing and past 12 months); and (iv) Psychosocial factors and comorbid conditions. CONCLUSION: The ISCIPEDS was designed to be used together with the International SCI Pain Basic Data Set and provide a brief yet thorough assessment of domains related to chronic pain in individuals with SCI. The data set includes pain-relevant self-reported assessments, questionnaires and sensory examinations. The recommendations were based on (i) their relevance to individuals with SCI and chronic pain, (ii) the existence of published findings supporting the utility of the selected measures for use in individuals with SCI, and to the greatest extent possible (iii) their availability in the public domain free of charge.

Thalamic activity and biochemical changes in individuals with neuropathic pain after spinal cord injury.

There is increasing evidence relating thalamic changes to the generation and/or maintenance of neuropathic pain. We have recently reported that neuropathic orofacial pain is associated with altered thalamic anatomy, biochemistry, and activity, which may result in disturbed thalamocortical oscillatory circuits. Despite this evidence, it is possible that these thalamic changes are not responsible for the presence of pain per se, but result as a consequence of the injury. To clarify this subject, we compared brain activity and biochemistry in 12 people with below-level neuropathic pain after complete thoracic spinal cord injury with 11 people with similar injuries and no neuropathic pain and 21 age- and gender-matched healthy control subjects. Quantitative arterial spinal labelling was used to measure thalamic activity, and magnetic resonance spectroscopy was used to determine changes in neuronal variability quantifying N-acetylaspartate and alterations in inhibitory function quantifying gamma amino butyric acid. This study revealed that the presence of neuropathic pain is associated with significant changes in thalamic biochemistry and neuronal activity. More specifically, the presence of neuropathic pain after spinal cord injury is associated with significant reductions in thalamic N-acetylaspartate, gamma amino butyric acid content, and blood flow in the region of the thalamic reticular nucleus. Spinal cord injury on its own did not account for these changes. These findings support the hypothesis that neuropathic pain is associated with altered thalamic structure and function, which may disturb central processing and play a key role in the experience of neuropathic pain.

The International Spinal Cord Injury Pain Basic Data Set (version 2.0).

OBJECTIVES: To revise the International Spinal Cord Injury Pain Basic Data Set (ISCIPBDS) based on new developments in the field and on suggestions from the spinal cord injury (SCI) and pain clinical and research community. SETTING: International. METHODS: The ISCIPBDS working group evaluated suggestions regarding the utility of the ISCIPBDS and made modifications in response to these and to significant developments in the field. The revised ISCIPBDS (version 2.0) was reviewed by members of the Executive Committee of the International SCI Standards and Data Sets, the International Spinal Cord Society (ISCoS) Executive and Scientific Committees, the American Spinal Injury Association and American Pain Society Boards and the Neuropathic Pain Special Interest Group of the International Association for the Study of Pain, individual reviewers and societies and the ISCoS Council. RESULTS: The ISCIPBDS (version 2.0) is significantly shortened but still contains clinically relevant core questions concerning SCI-related pain. The revisions include an updated SCI pain classification, omission of three questions regarding temporal pain pattern and three pain interference questions. The remaining three pain interference questions concern perceived interference with activities, mood and sleep for overall pain rather than for individual pain problems and are scored on a 0 to 10 scale.

Brain anatomy changes associated with persistent neuropathic pain following spinal cord injury.

Persistent neuropathic pain commonly occurs following spinal cord injury (SCI). It remains one of the most challenging management problems in this condition. In order to develop more effective treatments, a better understanding of the neural changes associated with neuropathic SCI pain is required. The aim of this investigation was to use diffusion tensor imaging (DTI) to determine if persistent neuropathic pain following SCI is associated with changes in regional brain anatomy and connectivity. In 23 subjects with complete thoracic SCI, 12 with below-level neuropathic pain and 11 without pain, and 45 healthy control subjects, a series of whole-brain DTI scans were performed. The mean diffusivity (MD) of each voxel was calculated and values compared between groups. This analysis revealed that neuropathic pain following SCI is associated with significant differences in regional brain anatomy. These anatomical changes were located in pain-related regions as well as regions of the classic reward circuitry, that is, the nucleus accumbens and orbitofrontal, dorsolateral prefrontal, and posterior parietal cortices. The right posterior parietal cortex projected to most regions that displayed an anatomical change. Analysis of the fiber tracts connecting areas of MD differences revealed no significance differences in MD values between the SCI pain, SCI no pain, and control groups.

Anatomical changes in human motor cortex and motor pathways following complete thoracic spinal cord injury.

A debilitating consequence of complete spinal cord injury (SCI) is the loss of motor control. Although the goal of most SCI treatments is to re-establish neural connections, a potential complication in restoring motor function is that SCI may result in anatomical and functional changes in brain areas controlling motor output. Some animal investigations show cell death in the primary motor cortex following SCI, but similar anatomical changes in humans are not yet established. The aim of this investigation was to use voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) to determine if SCI in humans results in anatomical changes within motor cortices and descending motor pathways. Using VBM, we found significantly lower gray matter volume in complete SCI subjects compared with controls in the primary motor cortex, the medial prefrontal, and adjacent anterior cingulate cortices. DTI analysis revealed structural abnormalities in the same areas with reduced gray matter volume and in the superior cerebellar cortex. In addition, tractography revealed structural abnormalities in the corticospinal and corticopontine tracts of the SCI subjects. In conclusion, human subjects with complete SCI show structural changes in cortical motor regions and descending motor tracts, and these brain anatomical changes may limit motor recovery following SCI.

Management of neuropathic pain following spinal cord injury: now and in the future.

OBJECTIVE: To provide an overview of our current understanding of the problem of neuropathic pain following spinal cord injury (SCI) and to suggest possible therapeutic options in the near future. METHODS: Original research articles, reviews and book chapters on the subject of pain and SCI. RESULTS: Neuropathic pain following SCI has presented a challenge not only for traditional concepts of how pain occurs but also for more recent conceptualizations. We have made substantial progress in identifying the common types of pain that occur following SCI, determining the prevalence and characteristics of pain, investigating some of the pathophysiological changes in the nervous system that may contribute to the presence of neuropathic SCI pain and examining the effectiveness of some treatments. However major challenges remain. We still need to reach consensus on an SCI pain taxonomy; our understanding of mechanisms and the relative contribution of changes in the periphery, spinal cord and brain is incompletely understood; there are few studies that indicate effective treatment options, particularly for neuropathic SCI pain; and treatment of the biological and psychological contributors to pain is often fragmented. CONCLUSION: Recent studies suggest the potential usefulness of new treatment approaches such as selective pharmacological agents, application of novel neurostimulation techniques and the use of cognitive approaches to modify the pain experience. Our increasing understanding of the problem combined with the promise of these new approaches offers hope for improved management of neuropathic pain following SCI in the near future.

Neuropathic pain and primary somatosensory cortex reorganization following spinal cord injury.

The most obvious impairments associated with spinal cord injury (SCI) are loss of sensation and motor control. However, many subjects with SCI also develop persistent neuropathic pain below the injury which is often severe, debilitating and refractory to treatment. The underlying mechanisms of persistent neuropathic SCI pain remain poorly understood. Reports in amputees describing phantom limb pain demonstrate a positive correlation between pain intensity and the amount of primary somatosensory cortex (S1) reorganization. Of note, this S1 reorganization has also been shown to reverse with pain reduction. It is unknown whether a similar association between S1 reorganization and pain intensity exists in subjects with SCI. The aim of this investigation was to determine whether the degree of S1 reorganization following SCI correlated with on-going neuropathic pain intensity. In 20 complete SCI subjects (10 with neuropathic pain, 10 without neuropathic pain) and 21 control subjects without SCI, the somatosensory cortex was mapped using functional magnetic resonance imaging during light brushing of the right little finger, thumb and lip. S1 reorganization was demonstrated in SCI subjects with the little finger activation point moving medially towards the S1 region that would normally innervate the legs. The amount of S1 reorganization in subjects with SCI significantly correlated with on-going pain intensity levels. This study provides evidence of a link between the degree of cortical reorganization and the intensity of persistent neuropathic pain following SCI. Strategies aimed at reversing somatosensory cortical reorganization may have therapeutic potential in central neuropathic pain.

The international spinal cord injury pain basic data set.

OBJECTIVE: To develop a basic pain data set (International Spinal Cord Injury Basic Pain Data Set, ISCIPDS:B) within the framework of the International spinal cord injury (SCI) data sets that would facilitate consistent collection and reporting of pain in the SCI population. SETTING: International. METHODS: The ISCIPDS:B was developed by a working group consisting of individuals with published evidence of expertise in SCI-related pain regarding taxonomy, psychophysics, psychology, epidemiology and assessment, and one representative of the Executive Committee of the International SCI Standards and Data Sets. The members were appointed by four major organizations with an interest in SCI-related pain (International Spinal Cord Society, ISCoS; American Spinal Injury Association, ASIA; American Pain Society, APS and International Association for the Study of Pain, IASP). The initial ISCIPDS:B was revised based on suggestions from members of the Executive Committee of the International SCI Standards and Data Sets, the ISCoS Scientific Committee, ASIA and APS Boards, and the Neuropathic Pain Special Interest Group of the IASP, individual reviewers and societies and the ISCoS Council. RESULTS: The final ISCIPDS:B contains core questions about clinically relevant information concerning SCI-related pain that can be collected by health-care professionals with expertise in SCI in various clinical settings. The questions concern pain severity, physical and emotional function and include a pain-intensity rating, a pain classification and questions related to the temporal pattern of pain for each specific pain problem. The impact of pain on physical, social and emotional function, and sleep is evaluated for each pain.

Electroencephalographic slowing and reduced reactivity in neuropathic pain following spinal cord injury.

STUDY DESIGN: Brain wave activity in people with paraplegia, with and without neuropathic pain, was compared to brain wave activity in matched able-bodied controls. OBJECTIVES: To investigate whether spinal cord injury with neuropathic pain is associated with a slowing of brain wave activity. SETTING: Australia. METHODS: Electroencephalographic (EEG) data were collected in the eyes open (EO) and eyes closed (EC) states from 16 participants with paraplegia (eight with neuropathic pain and eight without pain) and matched able-bodied controls. Common EEG artefacts were removed using independent component analysis (ICA). Peak frequency in the theta-alpha band and EEG power in the delta, theta, alpha and beta frequency bands were compared between groups. RESULTS: The results show significant slowing of the EEG in people with neuropathic pain, consistent with the presence of thalamocortical dysrhythmia (TCD). Furthermore, people with neuropathic spinal cord injury (SCI) pain had significantly reduced EEG spectral reactivity in response to increased or decreased sensory input flowing into the thalamocortical network, as modulated by the eyes open and eyes closed states. CONCLUSION: The results provide further evidence for alterations in brain electric activity that may underlie the development of neuropathic pain following SCI.

Impact of spinal cord injury on self-perceived pre- and postmorbid cognitive, emotional and physical functioning.

STUDY DESIGN: Cross-sectional study with repeated measurements. OBJECTIVES: To examine the patient's perspective of the impact of spinal cord injury (SCI) on physical, cognitive, emotional function, and quality of life (QOL). SETTING: Australia. METHODS: A sample of 63 patients with SCI, 32 of whom had recent injuries, and 31 with established injuries were administered the Ruff Neurobehavioral Inventory to examine patients' subjective evaluation of pre- and post-injury functioning. Current happiness levels were also evaluated using the Subjective Happiness Scale. A follow up assessment was performed 6 months later to examine changes over time. RESULTS: A significant difference was found between perception of pre- and postmorbid function on composite Cognitive (t=5.99, df=62, P<0.001), Physical (t=11.56, df=62, P<0.001), and QOL (t=7.16, df=62, P<0.001) scales and on several of the Emotional subscales including anxiety, paranoia and suspicion, and substance abuse (P<0.001). A series of hierarchical regression analyses indicate that post-SCI pain was a significant predictor of: cognitive (R(2)=0.20, P<0.001); emotional (R(2)=0.13, P<0.004); and of QOL (R(2)=0.22, P<0.001) functioning. With the exception of a decrease in happiness (P<0.01), there were no significant changes in any measures over the 6 month time period. CONCLUSIONS: There are significant changes in patients' perceptions of physical and cognitive functioning, and of QOL before and after SCI and some aspects of emotional functioning. Pain has a significant adverse effect on functioning. Happiness decreased slightly in the 6 months between surveys.

Pregabalin in central neuropathic pain associated with spinal cord injury: a placebo-controlled trial.

OBJECTIVE: To evaluate pregabalin in central neuropathic pain associated with spinal cord injury. METHODS: A 12-week, multicenter study of patients randomized to either flexible-dose pregabalin 150 to 600 mg/day (n = 70) or placebo (n = 67), administered BID. Patients were allowed to remain on existing, stable pain therapy. The primary efficacy variable was the endpoint mean pain score, derived from patients' last 7 days daily pain diary entries. Key secondary endpoints included pain responder rates, the SF-MPQ, sleep interference, mood, and the patient global measure of change. RESULTS: The mean baseline pain score was 6.54 in the pregabalin group and 6.73 in the placebo group. The mean endpoint pain score was lower in the pregabalin group (4.62) than the placebo group (6.27; p < 0.001), with efficacy observed as early as week 1 and maintained for the duration of the study. The average pregabalin dose after the 3-week stabilization phase was 460 mg/day. Pregabalin was significantly superior to placebo in endpoint assessments on the SF-MPQ. The > or =30% and > or =50% pain responder rates were higher with pregabalin than placebo (p < 0.05). Pregabalin was associated with improvements in disturbed sleep (p < 0.001) and anxiety (p < 0.05), and more patients reported global improvement at endpoint in the pregabalin group (p < 0.001). Mild or moderate, typically transient, somnolence and dizziness were the most common adverse events. CONCLUSIONS: Pregabalin 150 to 600 mg/day was effective in relieving central neuropathic pain, improving sleep, anxiety, and overall patient status in patients with spinal cord injury.

A proposed algorithm for the management of pain following spinal cord injury.

STUDY DESIGN: Review. OBJECTIVES: To review published articles on the assessment, diagnosis and treatment of pain following spinal cord injury (SCI) and to synthesise evidence from these materials to formulate and propose a systematic approach to management. METHODS: Relevant articles regarding the treatment of pain were identified from electronic databases using the search terms (('spinal cord injury' or 'spinal cord injuries') and 'pain') and both ('treatment') and ('randomised controlled trials'). Relevant articles were also identified through citations in indexed journal publications and book chapters on this topic. RESULTS: Review of the literature indicates that there are a large variety of treatments used in the management of pain following SCI with a small number supported by strong evidence for effectiveness. A treatment algorithm is proposed based on identification of underlying pain contributors and application of appropriate treatment. CONCLUSION: Although there are relatively few studies clearly indicating efficacy in this population, an algorithm for the management of pain following SCI might assist to maximise our effectiveness in the treatment of this condition. It is recognised that choice of treatment is also determined by factors such as medication availability, cost and side effects as well as the preferences and characteristics of the person being treated. Nevertheless, an algorithm is proposed as a way to synthesise our current level of knowledge, identify gaps for further study and aid in the management of this difficult problem.

Increased responsiveness of rat dorsal horn neurons in vivo following prolonged intrathecal exposure to interferon-gamma.

Prolonged increases in the level of the pro-inflammatory cytokine interferon-gamma occur in the CNS during some disease states associated with persistent pain. Administration of interferon-gamma to both humans and rodents has produced pain or pain-related behavior but the underlying mechanisms are unknown. The present study examined the effects of repeated intrathecal administration of interferon-gamma on dorsal horn neuronal responses under in vivo conditions. In addition, behavioral effects of interferon-gamma treatment were studied. Intrathecal cannulae were implanted into anesthetized rats. Animals then received either 1000 U of recombinant rat interferon-gamma in 10 microl buffer intrathecally, repeated four times over 8 days, or similarly administered buffer (controls). Interferon-gamma-treated animals showed a significant reduction in paw withdrawal threshold to mechanical stimulation of the hind paw. Electrophysiological experiments were performed under halothane anesthesia. Extracellular recordings of spontaneous and evoked responses were obtained from dorsal horn neurons (n=64) in the lumbar spinal cord. There was a significantly higher proportion of spontaneously active neurons in the interferon-gamma-treated animals (50%) when compared with controls (19%). A significantly increased proportion of neurons from interferon-gamma-treated animals displayed afterdischarges following both innocuous and noxious mechanical stimulation of the receptive field (brush: 21% in interferon-gamma-treated, 3% in controls; pinch: 97% in interferon-gamma-treated, 50% in controls). Neurons from interferon-gamma-treated animals also showed significantly increased wind-up of action potentials in response to repeated electrical stimulation of the sciatic nerve at C-fiber strength at both 0.5 and 1 Hz. Paired-pulse inhibition, evoked through electrical stimulation of the cutaneous receptive field, was significantly decreased in neurons from interferon-gamma-treated animals at 50 and 100 ms inter-stimulus intervals. We propose that this demonstrated reduction in inhibition may underlie the enhanced excitatory responses. Such interferon-gamma-induced changes in evoked responses may contribute to persistent pain following damage or disease states in the nervous system.

Thalamic neuronal activity in rats with mechanical allodynia following contusive spinal cord injury.

Pain and allodynia following spinal cord injury are poorly understood and difficult to treat. Since there is evidence that supraspinal mechanisms are important in such pain, we have studied the role of the thalamus in an experimental model of spinal injury. Extracellular recordings were obtained from neurones of the thalamic nucleus ventralis postero-lateralis (VPL) in normal rats and those which had sustained a contusive spinal cord injury to the thoraco-lumbar junction 7 days previously. Behavioural testing with von Frey hairs established that 11 spinally injured rats showed exaggerated vocal responses to normally innocuous mechanical stimulation (allodynia) whereas eight were non-allodynic. Thalamic VPL neurones in spinally injured rats (both allodynic and non-allodynic) exhibited a dysrhythmia in that a significantly higher proportion fired spontaneously in an oscillatory mode when compared with neurones in uninjured rats. Thus this dysrhythmia was linked to spinal injury, not to allodynia. The evoked responses of VPL thalamic neurones to brushing the skin, however, were significantly elevated in allodynic rats when compared with those in uninjured rats and neuronal afterdischarges to these stimuli (which were absent in uninjured rats) were more common in allodynic than in non-allodynic rats. We have previously reported that a proportion of spinal neurones in allodynic spinally injured rats show increased evoked responses and afterdischarges following brushing the skin and hence the enhanced thalamic responses may reflect a greater spinal input. In view of the increasing evidence that thalamo-cortical rhythmical firing is linked to sensorimotor and cognitive brain functions, we propose that pain following brushing the skin results from an exaggerated spinal input being processed by a dysrhythmic thalamus. Thus both spinal and thalamic mechanisms may be important in the genesis of pain and allodynia following spinal cord injury.

Pain following spinal cord injury.

Chronic pain is an important problem following spinal cord injury (SCI) and is a major impediment to effective rehabilitation. The reported prevalence of chronic SCI pain is variable but averages 65% with around one third of these people rating their pain as severe. The mechanisms responsible for the presence of pain are poorly understood. However, evidence from clinical observations and the use of animal models of SCI pain suggests that a number of processes may be important. These include functional and structural plastic changes in the central nervous system following injury, with changes in receptor function and loss of normal inhibition resulting in an increased neuronal excitability. A number of specific types of SCI pain can be distinguished based on descriptors, location and response to treatment. Nociceptive pain can arise from musculoskeletal structures and viscera and neuropathic pain can arise from spinal cord and nerve damage. The role of psychological and environmental factors also needs to be considered. Accurate identification of these pain types will help in selecting appropriate treatment approaches. Current treatments employ a variety of pharmacological, surgical, physical and psychological approaches. However, evidence for many of the treatments in use is still limited. It is hoped that future research will identify effective treatment strategies that accurately target specific mechanisms.