The Pain Course: exploring the feasibility of an internet-delivered pain management programme for adults with spinal cord injury.

STUDY DESIGN: Single-group feasibility clinical trial. OBJECTIVES: This study examined the feasibility and outcomes of a modified version of a validated internet-delivered pain management programme, the Pain Course, for adults with SCI. SETTING: Nationwide in Australia. METHODS: Sixty-eight adults participated in the programme, which comprises five online lessons and homework tasks that are systematically released over 8 weeks. Participants were supported through the course with weekly contact from a clinical psychologist. RESULTS: Eighty-five percent of participants provided data at post-treatment and 76% of participants completed all five lessons of the course. High levels of satisfaction were observed and relatively little clinician time (M = 93.16 min; SD = 52.76 min) was required per participant to provide the course. Preliminary evidence of clinical improvements in pain-related disability (ds ≥ 0.53.; avg. improvement ≥ 20%; Mdiff ≥ 7.77), depression (ds ≥ 0.44.; avg. improvement ≥ 24%; Mdiff ≥ 2.44), anxiety (ds ≥ 0.41.; avg. improvement ≥ 26%; Mdiff ≥ 1.8) and average pain intensity (ds ≥ 0.46.; avg. improvement ≥ 13%; Mdiff ≥ 0.71) were observed at post-treatment, which were maintained or further improved to 3-month follow-up. These improvements were reflected in overall improvements in self-reported satisfaction with life (ds ≥ 0.31; avg. improvement ≥ 25%; Mdiff ≥ 2.16) CONCLUSION: These findings highlight the potential of carefully developed internet-delivered interventions as an approach for overcoming barriers and increasing access to psychosocial care for adults with SCI. SPONSORSHIP: iCare Lifetime Care and Support Authority and the Australian National Health and Medical Research Council.

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 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.

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 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.

International spinal cord injury pain classification: part I. Background and description. March 6-7, 2009.

STUDY DESIGN: Discussion of issues and development of consensus. OBJECTIVE: Present the background, purpose, development process, format and definitions of the International Spinal Cord Injury Pain (ISCIP) Classification. METHODS: An international group of spinal cord injury (SCI) and pain experts deliberated over 2 days, and then via e-mail communication developed a consensus classification of pain after SCI. The classification was reviewed by members of several professional organizations and their feedback was incorporated. The classification then underwent validation by an international group of clinicians with minimal exposure to the classification, using case study vignettes. Based upon the results of this study, further revisions were made to the ISCIP Classification. RESULTS: An overall structure and terminology has been developed and partially validated as a merger of and improvement on previously published SCI pain classifications, combined with basic definitions proposed by the International Association for the Study of Pain and pain characteristics described in published empiric studies of pain. The classification is designed to be comprehensive and to include pains that are directly related to the SCI pathology as well as pains that are common after SCI but are not necessarily mechanistically related to the SCI itself. CONCLUSIONS: The format and definitions presented should help experienced and non-experienced clinicians as well as clinical researchers classify pain after SCI.

International Spinal Cord Injury Pain (ISCIP) Classification: Part 2. Initial validation using vignettes.

STUDY DESIGN: International validation study using self-administered surveys. OBJECTIVES: To investigate the utility and reliability of the International Spinal Cord Injury Pain (ISCIP) Classification as used by clinicians. METHODS: Seventy-five clinical vignettes (case histories) were prepared by the members of the ISCIP Classification group and assigned to a category by consensus. Vignettes were incorporated into an Internet survey distributed to clinicians. Clinicians were asked, for each vignette, to decide on the number of pain components present and to classify each using the ISCIP Classification. RESULTS: The average respondent had 86% of the questions on the number of pain components correct. The overall correctness in determining whether pain was nociceptive was 79%, whereas the correctness in determining whether pain was neuropathic was 77%. Correctness in determining if pain was musculoskeletal was 84%, whereas for visceral pain, neuropathic at-level spinal cord injury (SCI) and below-level SCI pain it was 85%, 57% and 73%, respectively. Using strict criteria, the overall correctness in determining pain type was 68% (versus an expected 95%), but with maximally relaxed criteria, it increased to 85%. CONCLUSIONS: The reliability of use of the ISCIP Classification by clinicians (who received minimal training in its use) using a clinical vignette approach is moderate. Some subtypes of pain proved challenging to classify. The ISCIP should be tested for reliability by applying it to real persons with pain after SCI. Based on the results of this validation process, the instructions accompanying the ISCIP Classification for classifying subtypes of pain have been clarified.

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.

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.

Relationship between cardiovascular neurones and descending antinociceptive pathways in the rostral ventrolateral medulla of the cat.

It has been previously reported that injection of neuroexcitatory compounds into the rostral ventrolateral medulla (RVLM) can produce an inhibition of nociceptive reflexes, often associated with a rise in arterial blood pressure. The aim of this study was to determine whether the subretrofacial (SRF) nucleus, which is a highly circumscribed group of cells within the RVLM known to play a major role in cardiovascular regulation also has an antinociceptive function. In barbiturate-anaesthetised and paralysed cats, unilateral microinjections of the neuroexcitatory compound sodium glutamate (8-20 nl of 0.5 M solution) into the SRF nucleus produced large increases in mean arterial pressure but had only small and inconsistent effects on the simultaneously measured ventral root responses to stimulation of primary afferent C-fibres. On the other hand, glutamate microinjections into RVLM sites closely adjacent to the SRF nucleus, or into the nucleus raphe magnus, produced powerful inhibition of the C-fibre evoked response in the ventral root which was accompanied by no or only small changes in arterial pressure. It is concluded that the SRF pressor cells do not exert any control over nociceptive spinal reflexes, but that such a function may be served by cells in closely adjacent parts of the RVLM. Moreover, the method of recording C-fibre evoked responses in ventral roots as a measure of the magnitude of nociceptive spinal reflexes, combined with the glutamate microinjection procedure, was shown to have a sufficient resolution to allow an accurate mapping of the location of antinociceptive cell groups within the ventrolateral medulla.

Pain report and the relationship of pain to physical factors in the first 6 months following spinal cord injury.

A prospective, longitudinal study of 100 people with traumatic spinal cord injury (SCI) was performed to determine the time of onset. prevalence and severity of different types of pain (musculoskeletal, visceral, neuropathic at level, neuropathic below level) at 2, 4, 8, 13 and 26 weeks following SCI. In addition, we sought to determine the relationship between physical factors such as level of lesion, completeness and clinical SCI syndrome and the presence of pain. At 6 months following SCI, 40% of people had musculoskeletal pain, none had visceral pain, 36% had neuropathic at level pain and 19% had neuropathic below level pain. When all types of pain were included, at 6 months following injury, 64% of people in the study had pain, and 21% of people had pain that was rated as severe. Those with neuropathic below level pain were most likely to report their pain as severe or excruciating. There was no relationship between the presence of pain overall and level or completeness of lesion, or type of injury. Significant differences were found, however, when specific types of pain were examined. Musculoskeletal pain was more common in people with thoracic level injuries. Neuropathic pain associated with allodynia was more common in people who had incomplete spinal cord lesions, cervical rather than thoracic spinal cord lesions, and central cord syndrome. Therefore, this study suggests that most people continue to experience pain 6 months following spinal cord injury and 21% of people continue to experience severe pain. While the presence or absence of pain overall does not appear to be related to physical factors following SCI, there does appear to be a relationship between physical factors and pain when the pain is classified into specific types.

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.

Allodynia following traumatic spinal cord injury in the rat.

A weight-drop model of spinal cord injury was used to characterize the sensory changes that occur following mechanical trauma to the spinal cord and to determine the relationship of these changes to the extent of lesion. Weight-drop from different heights resulted in significant differences in motor dysfunction between experimental groups. These groups also demonstrated significant differences in the incidence of allodynia (decreased vocalization threshold to mechanical pressure). The incidence of allodynia was higher in the group that had incomplete spinal cord lesions confined to the central and dorsal regions of the spinal cord and lower in the groups that had either more extensive spinal cord damage or no apparent damage.

Descending antinociceptive pathway from the rostral ventrolateral medulla: a correlative anatomical and physiological study.

Microinjections of the excitatory amino acid L-glutamate were made into the rostral ventrolateral medulla (RVLM) of anesthetised cats, to map the sites at which selective stimulation of cell bodies elicited a significant antinociceptive response (> or = 15% inhibition of the increase in L7 ventral root activity reflexly evoked by stimulation of C-fiber afferents). Antinociceptive sites were largely confined to the RVLM subregion ventromedial to the retrofacial nucleus, extending from the caudal pole of the facial nucleus to the level approximately 2.5 mm more caudal. Increases in arterial pressure were also elicited from some sites in the RVLM, but these were mainly lateral to the antinociceptive sites. In a second series of experiments, rhodamine labeled microspheres or cholera toxin B-gold (CTB-gold) were injected into the dorsal horn of the L7 segment. In three of these experiments in which the injection sites were restricted to the dorsal horn, retrogradely labeled cells in the caudal pons and medulla were virtually all within either the nucleus raphe magnus or the RVLM. Furthermore, the labeled cells in the RVLM were virtually confined to a discrete group located just ventromedial to the retrofacial nucleus, i.e. within the antinociceptive region as mapped by glutamate microinjection. The results of the present study indicate that antinociceptive effects are elicited by stimulation of a subregion in the RVLM, which is located medial to the pressor region. Further, the antinociceptive effects may be mediated, at least in part, by cells projecting directly to the dorsal horn in the spinal cord.

Responses of spinal neurones to cutaneous and dorsal root stimuli in rats with mechanical allodynia after contusive spinal cord injury.

The firing of neurones in spinal segments adjacent to a contusive T13 spinal cord injury was characterised in anaesthetised rats. Three groups of rats were examined: (1) allodynic spinally injured, (2) non-allodynic spinally injured and (3) normal, uninjured. Spinal cord field potentials evoked by electrical dorsal root stimulation and the responses of 207 dorsal horn neurones to mechanical stimuli applied to the skin were studied. Within the lesioned spinal segment few active neurones were encountered and field potentials were absent. Depolarising field potentials recorded rostral to the lesion were reduced in both allodynic and non-allodynic animals compared to uninjured controls, while those recorded in caudal segments were enhanced in allodynic animals. Neuronal recordings revealed that allodynia was associated with exaggerated responses, including afterdischarges, to innocuous and noxious mechanical stimuli in a proportion of wide dynamic range, but not low threshold, neurones. These changes were observed both rostral and caudal to the site of injury. The results suggest that an increased responsiveness of some dorsal horn neurones in segments neighbouring a contusive spinal cord injury may contribute to the expression of mechanical allodynia. It is proposed that a relative lack of inhibition underlies altered cell responses.

C-fos expression in the spinal cord of rats exhibiting allodynia following contusive spinal cord injury.

Contusive spinal cord injury (SCI) may result in central neuropathic pain marked by allodynia-like features in the dermatomes close to the level of injury. The aim of this study was to compare the laminar distribution of activated neurons (as determined by c-fos immediate early gene expression) in the spinal cord immediately above the level of a SCI in rats with or without allodynia-like features. Non-noxious mechanical stimulation was applied to half the animals in the dermatomes corresponding to the level of injury prior to perfusion. Stimulation resulted in a significant increase in c-fos labelling in all laminae of the spinal dorsal horn in the segment immediately above the level of injury only in allodynia animals. Animals that had allodynia also demonstrated a significant increase in the level of c-fos labelling in lamina III, IV and V of the dorsal horn without stimulation. Thus, allodynia following SCI is associated with significant increases in basal and evoked c-fos expression ("neuronal activity") in response to non-noxious mechanical stimulation. The data also suggest that allodynia-like behaviour following SCI cannot be accounted for solely by changes occurring at a spinal level.