Classification of pain following spinal cord injury

Chronic spinal cord injury induced changes in the responses of thalamic neurons

Sensory disturbances following spinal cord injury (SCI) include chronic pain, which is often localized at spinal levels just rostral to the lesion (referred to as at-level neuropathic pain) and not effectively relieved by traditional treatments. In the present study, a clinically relevant spinal contusion injury was made at the spinal T8 level in 11 deeply anesthetized male rats. Behavioral testing just prior to terminal electrophysiological experiments (done at 30 days post-injury) demonstrated at-level sensitivity to touching the trunk (i.e., allodynia) in 64% of the animals. Electrophysiological data (urethane anesthesia) were obtained for 218 single somatovisceral convergent neurons that were located throughout 12 subregions of the thalamus. In total, 90% (197 of 218) responded to noxious at-level pinch, compared to 52% for pinching the dorsal trunk at the same level in uninjured controls (our previously published data--recorded from 133 total neurons). In addition, 33% of the total neurons tested also responded to gentle touch (dorsal trunk) versus 9% in controls. A comparison of electrophysiological and behavioral data for each individual animal reveals novel tactile neuronal responses within ventral and posterior thalamic subnuclei for those rats showing signs of at-level allodynia. These data suggest that neurons in specific regions of thalamus undergo significant changes in responsiveness following severe chronic SCI. The observed plasticity and ensuing hypersensitivity are likely part of the central reorganization producing the multitude of sensory disturbances that surface following SCI.

Health Status Rated With the Medical Outcomes Study 36-Item Short-Form Health Survey After Spinal Cord Injury

OBJECTIVE

To describe the health status of Australians with spinal cord injury (SCI).

DESIGN

Survey.

SETTING

Australian population-based sample.

PARTICIPANTS

Participants (N=305) with SCI at recruitment to a randomized trial.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) health questionnaire.

RESULTS

Compared with the general population, our sample reported significantly lower scores in 6 SF-36 domains (physical function, role-physical, bodily pain, general health, social function, vitality) and the physical component summary (PCS) score, but unexpectedly higher mental component summary (MCS) scores (difference in mean MCS scores, 4.6; 95% confidence interval [CI], 2.4-6.8). Compared with people with tetraplegia, those with paraplegia had better physical function and PCS scores (difference, 21; 95% CI, 17-24; difference, 3; 95% CI, 1-5, respectively), and worse bodily pain scores (difference, 9; 95% CI, 2-15). Recent urinary infections were associated with worse general health, vitality, mental health, and MCS scores. Receiving family or external physical care was associated with worse physical function and PCS scores, but better mental health and MCS scores. Older age at injury was associated with lower bodily pain and PCS scores.

CONCLUSIONS

Using the SF-36, Australians with SCI rate their physical (not mental) health status as worse than the general population.

Pain following spinal cord injury: the impact on community reintegration

STUDY DESIGN

Prospective, correlational.

OBJECTIVES

(1) Describe how pain changes over recovery from admission to spinal cord injury (SCI) rehabilitation, discharge and after 6 months of community living and (2) examine the relationship between pain and community integration at 6 months of community living.

SETTING

Tertiary rehabilitation centre, SCI unit, Vancouver, Canada.

METHODS

Subjects from 66 consecutive admissions to the SCI Program of a tertiary rehabilitation centre for the treatment of a traumatic SCI during the years 2000-2002 were followed using data from the National Rehabilitation Reporting System (NRS). Information was obtained from NRRS standardized assessments performed on admission, discharge and 6 months of community living. Early community living was defined as 6 months postdischarge. Community reintegration was assessed by the Reintegration to Normal Living Index (RNL). Pain presence, pain impact and pain intensity were assessed using single item Likhert-type scales.

RESULTS

In all, 86% of individuals with a SCI reported pain at 6 months postdischarge, with 27% of these individuals reporting pain that impacted on many or most activities. Pain impact and pain intensity were related to the community reintegration (r = -0.39 and -0.55, P < 0.001), with pain intensity accounting for 25% of the variance in RNL scores.

CONCLUSIONS

Pain is a major consequence of a SCI, impacting on an individual's activities and perception of how well they are integrated into the community. The results of this study highlight the need to address pain during both the rehabilitation phase of treatment and the early transition into the community.

Neuropathic pain after traumatic spinal cord injury--relations to gender, spinal level, completeness, and age at the time of injury

STUDY DESIGN

Retrospective register study.

OBJECTIVE

To investigate the predictive value of age at the time of injury, gender, level of injury, and completeness of injury for the development of at level and below level neuropathic pain.

SETTING

"Spinalis", a postacute spinal cord injury (SCI) outpatient clinic, serving the greater Stockholm area (Sweden).

METHOD

All patients who visited the clinic in 1995-2000 (402 patients) for the first time were examined. The following items were selected: at-level and below-level neuropathic pain according to the International Association for the Study of Pain (IASP) criteria, age at the time of injury, gender, level of injury according to ASIA, and completeness of injury. Mean time of 6 years after the injury. Results were analysed with chi(2) analysis and logistic regression.

RESULTS

Of all patients examined, 13% had at level pain and 27% had below level pain. Neuropathic pain was less than half as frequent (26%) in the group aged less than 20 years at the time of injury as in the oldest group (58%). The increasing trend was mainly due to below-level pain up to 39 years of age, and due to at-level pain at ages 40 and above at the time of injury. No correlation was observed to gender, level of injury or completeness of injury, except for below level pain, which was associated with complete injury.

CONCLUSION

The results show that neuropathic pain after SCI is common and occurs much more often in patients injured at higher ages. This indicates the importance of neuroanalgetic intervention, in particular for patients injured in higher ages.

Pain management with interventional spine therapy in patients with spinal cord injury: a case series

BACKGROUND/OBJECTIVE

Chronic pain is common in patients with spinal cord injury (SCI). Any new strategy that is effective in treating this problem would be welcomed by this patient population.

METHODS

A case series is presented of SCI with neuropathic pain. In these 3 cases, interventional spine therapy is used as a diagnostic and/or therapeutic tool in the management of pain.

RESULTS

In the cases presented, interventional spine therapy proved useful in identifying the patient's pain generator. In most cases, the intervention was effective in reducing pain for a long enough period to serve as an effective pain management strategy. Other associated problems, such as spasticity, were similarly reduced.

CONCLUSION

Interventional spine therapy should be considered as a tool in the armamentarium of any SCI physician managing their patient's chronic pain.

Visceral pain and life quality in persons with spinal cord Injury: a brief report

BACKGROUND/OBJECTIVE

Few studies have examined the prevalence of visceral pain in persons with spinal cord injury (SCI), and virtually no studies have looked at the relationship between visceral pain and self-reported quality of life. We examined the frequency of reported visceral pain at 5, 10, and 15 years after injury to determine whether the presence of visceral pain is related to quality of life, and to determine to what extent visceral pain should be of concern to clinicians treating patients with SCI.

METHODS

Visceral pain and quality of life in persons with SCI were compared from a combined Craig Hospital and National Model SCI Systems database at 5 (N = 33), 10 (N = 132), and 15 (N = 96) years after injury.

RESULTS

The rates of visceral pain increased at each measurement (10% at year 5, 22% at year 10, and 32% at year 15); although these numbers reflect cross-sectional data, they do show a clear statistical change. Only a limited true longitudinal sample was available, but at 10 years after injury, individuals who had reported visceral pain at any time reported a significantly lower quality of life than those never experiencing visceral pain, F1,188 = 3.95, P < 0.05.

CONCLUSIONS

Although visceral pain may not be as prevalent as the more researched neuropathic and musculoskeletal subtypes of pain, it may account for a higher percentage of people with SCI who report pain than previously recognized. More quantitative and longitudinal research is needed to examine the relationship of visceral pain with overall quality of life and to pursue interventions.

Effects of surgery on the sensory deficits of syringomyelia and predictors of outcome: a long term prospective study

OBJECTIVE

To quantify the effects of surgery on the thermal deficits of syringomyelia and assess the predictors for such effects.

METHODS

The subjects were 16 consecutive patients (12 men, 4 women; mean (SD) duration of sensory symptoms, 5.1 (4.5) years) presenting with the typical symptoms of syringomyelia related to Chiari I malformation or trauma, and requiring surgical treatment. They were evaluated before surgery, then at six months and two years. Sensory evaluation included determination of the extent of thermal deficits and quantitative assessment of thermal, mechanical, vibration detection, and pain thresholds. Neuropathic pain intensity was evaluated on visual analogue scales. Magnetic resonance imaging was done before and after surgery to measure syrinx dimensions.

RESULTS

The magnitude and extent of thermal deficits improved in a subgroup of patients and this was best predicted by the duration of sensory symptoms: patients operated on less than two years after the onset of their symptoms tended to improve, while those operated on later were stabilised or deteriorated slightly. The effect of surgery on thermal deficits was correlated with the duration of sensory symptoms. Surgery also affected vibration deficits in patients with the Chiari malformation, neuropathic pain on effort, and syrinx dimensions.

CONCLUSIONS

The duration of sensory deficits is the best predictive factor of the efficacy of surgery for the thermal symptoms of syringomyelia. Early surgery is required if these deficits are to be minimised.

Spinal cord injury pain--mechanisms and treatment

In spinal cord injury (SCI), pain is a major cause of disability. A review of experimental and human studies, which provide insight into the mechanisms and treatment of SCI neuropathic pain are presented. Each of a series of pathophysiologic changes after SCI may be relevant for the development of SCI neuropathic pain. These changes are discussed in relation to neuropathic pain at and below the level of SCI. SCI neuropathic pain is difficult to treat. Experimental and human randomized, double-blind, placebo-controlled, clinical trials on pharmacologic treatment of SCI pain are summarized.

Ketamine patient-controlled analgesia for dysesthetic central pain

STUDY DESIGN

Case report.

OBJECTIVES

To describe the first use of intravenous (IV) ketamine as the sole agent in a patient-controlled analgesic delivery system (ie PCA) in a patient with cervical syringomyelia.

SETTING

A tertiary-care university teaching hospital in New York City.

METHODS

A 41-year-old tetraplegic female on high-dose opioids suffering from intractable dysesthetic central pain received her best pain relief from a low-dose ketamine infusion after failing trials with multiple neuropathic medications. After several weeks of titrating her infusion rate up and down, she was switched to an IV ketamine PCA device.

RESULTS

The patient was maintained on an IV ketamine PCA for almost 1 year under the following settings: 2.7 mg/h basal rate; 2.7 mg/h demand dose; 15 min lockout period. Although she continues to report some pain, it has dramatically decreased since the ketamine PCA was instituted, enabling us to significantly reduce her opioid dosage.

CONCLUSIONS

Ketamine PCA may be a viable treatment option in patients suffering from intractable central pain. The rationale for this treatment, along with dosing guidelines and possible drawbacks, is discussed.

Conditions affecting the onset, severity, and progression of a spontaneous pain-like behavior after excitotoxic spinal cord injury

Intraspinal injection of quisqualic acid (QUIS) is associated with the development of spontaneous excessive grooming behavior in male Sprague Dawley rats. To further characterize this pain-like behavior we evaluated the relationship between the onset of this behavior and the rostrocaudal spread of injury-induced neuronal loss in 3 different strains of male rats. The severity and progression of this behavior also were evaluated. Unilateral intraspinal injections of 125 mmol/L QUIS were made in the following groups: Sprague Dawley males (SDMs, n = 21); Long Evans males (LEMs, n = 17); and Wistar Furth males (WFMs, n = 11). Because of differences in grooming characteristics between male and female rats, the modulatory effects of female gonadal hormones also were evaluated in Sprague Dawley females (SDFs, n = 17); bilaterally ovariectomized Sprague Dawley females (OVXs, n = 11); and SDMs treated with either 17-beta-estradiol (50 microg/kg; SDM-Est, n = 9) or progesterone (5 mg/kg; SDM-Pro, n = 11). The results showed that the development of excessive grooming behavior in males of all strains and ovariectomized females is related to the rostrocaudal spread of a specific pattern of neuronal loss in the dorsal horn. Excessive grooming behavior in SDFs was similar in many respects to that found in SDMs; however, SDFs did not show a dependence on the longitudinal extent of injury for the onset of this behavior. The onset, severity, and progression of excessive grooming in OVX females were similar to that found in SDMs. Furthermore, 8 of 9 estradiol-treated SDMs developed severe grooming characterized by an early onset and progressive time course, whereas progesterone treatment delayed the onset of grooming and attenuated its severity and progression. Strain-related differences in some, but not all, grooming characteristics also were observed, eg, WFMs exhibited more aggressive grooming than SDMs or LEMs. In conclusion, the results showed gender, strain, and gonadal hormones influence the onset and progression of injury-induced excessive grooming behavior. A causal relationship also was found between the onset of this behavior and the longitudinal extent of injury.

Spinal cord injury pain

Awareness that SCI pain is common emerged during the past decade. However, there are a number of unresolved issues. There is a need for variety of experimental models to reflect diversity of SCI pains. Current classification is not as user-friendly as it should be. More attention should be given to a condition of the spinal cord below and above the SCI lesion. A consensus for what is an optimal SCI functional assessment for patients with sensory complaints and pain should be developed. Further extensive SCI pain research is needed prior to spinal cord regeneration trials in order to be able to cope with a potential for newly developed pains that may appear during incomplete spinal cord regenerative attempts.

Types and effectiveness of treatments used by people with chronic pain associated with spinal cord injuries: influence of pain and psychosocial characteristics

STUDY DESIGN

Postal survey.

OBJECTIVES

Because of the high prevalence and inadequate control of pain following spinal cord injury (SCI), it is important to have information about the factors associated with the use of specific pain therapies. We conducted this study to evaluate the ability of pain characteristics and psychosocial factors to predict the use of treatments.

SETTING

The Miami Project to Cure Paralysis (Miami, FL, USA).

METHODS

People with SCI (n=120) were mailed a packet containing a questionnaire with questions regarding demographic factors, pain characteristics, and pain treatments along with a copy of the Multidimensional Pain Inventory.

RESULTS

A total of 59% of the respondents had been prescribed treatment or self-initiated efforts to treat pain over the previous 18-month period. The most common treatments used by this sample were massage (26.6%), opioids (22.5%) and nonsteroidal anti-inflammatory drugs (NSAIDs) (20%). The most effective treatments overall were 'physical therapies' with 50% receiving these treatments indicating that their pain was 'considerably reduced' or that they were 'pain free.' Opioids and anticonvulsants were perceived to be the most effective pharmacological agents prescribed (33.3 and 23.8% reporting their pain was considerably better or eliminated, respectively). People using prescription medication reported significantly greater pain severity, more widespread pain, more descriptive adjectives, more evoked pain, greater difficulty in dealing with pain, and more interference and decreased activity levels due to pain, compared to people not using prescription medication. A combination of greater difficulty in dealing with pain, intense pain, presence of evoked pain, and higher level of perceived support from significant others was predictive of taking prescription medication.

CONCLUSION

People taking prescription medication reported significantly more intense pain with neuropathic characteristics that significantly affected daily life and routine activities. A substantial percentage of individuals with pain related to SCI did not obtain significant pain relief from prescription medications. None of the factors assessed predicted the use of nonprescription treatments. The results of this study confirm the inadequacy of available modalities to manage chronic pain related to SCI.

Maintenance of exercise participation in individuals with spinal cord injury: effects on quality of life, stress and pain

STUDY DESIGN

Follow-up study of seven individuals with spinal cord injury (SCI) who completed a 9-month randomized control trial (RCT) of exercise training.

OBJECTIVE

In a 9-month RCT conducted in our lab, individuals with SCI who participated in a twice-weekly supervised exercise training reported greater perceived quality of life (PQOL), and less stress and pain than a nonexercising control cohort. The present follow-up study examined the voluntary continuation of exercise training after the study ended and the persistence of the accrued psychosocial benefits.

SETTING

Centre for Health Promotion and Rehabilitation, McMaster University, Hamilton, Ontario, Canada.

METHODS

Five men and two women (age 42.3+/-3.6 years) with SCI (C5-T12; ASIA A-D 12.7+/-8.2 years postinjury) were invited to continue supervised exercise training twice weekly at the completion of the 9-month RCT. Exercise adherence, PQOL, stress and bodily pain were measured at a 3-month follow-up and were compared to values obtained at baseline, and at 3, 6 and 9 months during the intervention.

RESULTS

There was a significant decrease in adherence at the 3-month follow-up compared to the overall 9-month adherence rate (42.7 versus 80.6%, respectively; P<0.01). There was also a significant decrease in PQOL (P<0.05) and a trend for increased pain (P=0.07) and stress (P=0.12), at follow-up compared to the end of the 9-month trial. Finally, there was a significant negative correlation between pain at the conclusion of the RCT and exercise adherence over the 3-month follow-up period (r=-0.91; P<0.01).

CONCLUSIONS

These findings emphasize the importance of continued exercise adherence to the maintenance of exercise-related increases in psychological well-being among individuals with SCI.

Allodynia after acute intrathecal morphine administration in a patient with neuropathic pain after spinal cord injury

IMPLICATIONS

Acute intrathecal administration of relatively small doses of opioids may precipitate neuropathic pain and allodynia in those with spinal cord injury.

A longitudinal study of the prevalence and characteristics of pain in the first 5 years following spinal cord injury

A longitudinal cohort study of 100 people with traumatic spinal cord injury (SCI) was performed to determine the prevalence and severity of different types of pain (musculoskeletal, visceral, neuropathic at-level, neuropathic below-level) at 5 years following SCI. Prospective data on the characteristics of pain up to 6 months following injury had been collected previously and allowed comparisons between the presence of pain at different time points. In addition, we sought to determine the relationship between the presence of pain and physical factors related to the injury such as level of lesion, completeness and clinical SCI syndrome. We also obtained information regarding mood, global self-rated health and the impact of pain on function. Of the 100 subjects in the original cohort, 73 were available for follow up. When all types of pain were included, 59 of the 73 subjects (81%) reported the presence of pain. Musculoskeletal pain was the most common type of pain experienced and was present in 43 subjects (59%), at-level neuropathic pain was present in 30 subjects (41%), below-level neuropathic pain was present in 25 subjects (34%) and visceral pain was present in four subjects (5%). Overall, 58% reported their pain as severe or excruciating and those with visceral pain were most likely to rate their pain in these categories. There was no relationship between the presence of pain overall and level or completeness of lesion, or type of injury. However, tetraplegics were more likely to report below-level neuropathic pain. This study prospectively demonstrates the differing time courses of different types of pain over the first 5 years following SCI. There was a strong correlation between the presence of both types of neuropathic pain at 5 years and earlier time points but both visceral pain and musculoskeletal pain demonstrated a poor correlation between time points. Chronic visceral pain occurs in a small percentage of patients and does not correlate with the presence of visceral pain early following injury. Those with neuropathic pain early following their injury are likely to continue to experience ongoing pain and the pain is likely to be severe. In contrast, chronic musculoskeletal pain is more common but less likely to be severe and cannot be predicted by the presence of pain in the first 6 months following injury.

Pain characteristics in patients admitted to hospital with complications after spinal cord injury

OBJECTIVES

To determine characteristics of pain, the relation between pain and mood, the effect of pain on activities, and the perceived difficulty in coping with pain in patients hospitalized for treatment of complications associated with spinal cord injury (SCI).

DESIGN

Cohort survey.

SETTING

Hospital inpatient unit in Australia.

PARTICIPANTS

Consecutive sample of patients (N=88) admitted to a hospital spinal injuries unit with complications after SCI. Two eligible patients declined to participate.

INTERVENTION

Face-to-face interview with questionnaire.

MAIN OUTCOME MEASURES

Pain severity, global self-rated health, mood (Kessler Mood Inventory), and interference with activities (Von Korff disability scale).

RESULTS

Sixty-six (75%) of the 88 subjects experienced pain, with an average time of onset +/- standard deviation of 8.02+/-12.4 years; 27% of those with pain described it as severe or excruciating. Subjects with pain were less likely to rate their global health as excellent or very good when compared with those who did not have pain (22% vs 44%, respectively). Patients with pain had significantly greater levels of psychologic distress than did people with SCI and no pain.

CONCLUSIONS

Pain is a common problem in people admitted to hospital with SCI for treatment of other complications. It has a significant impact on activities and is associated with a reduction in global self-rated health and higher levels of psychologic distress.

Test-retest reliability of the Donovan spinal cord injury pain classification scheme

STUDY DESIGN

Videotape rating by independent viewers.

OBJECTIVE

To determine the test-retest reliability of the Donovan spinal cord injury (SCI) pain classification scheme.

SETTING

Rehabilitation Centre, Alabama, USA.

METHODS

A total of 28 individuals with SCI reported 60 pain sites. A structured interview and physical exam were used to illicit information to classify each pain site according to the Donovan criteria. All structured interviews and exams were videotaped. Three independent raters viewed the videotapes on two occasions, separated by a 3-month interval, and classified each pain site using the Donovan pain classification scheme.

RESULTS

Considering all three raters together, 78% of the pain sites were consistently classified from one period to the next. Within each rater, consistent classification ranged from 67 to 83%. However, inter-rater agreement for the classification of each pain site into the various types of pain was low for both periods (about 50-60%).

CONCLUSIONS

Pain classification within each rater generally showed adequate test-retest reliability when using the Donovan SCI pain classification scheme. However, reliability estimates of agreement across raters highlight the ongoing need to exam and improve the psychometric characteristics of the various pain classification schemes.

Investigating neck pain in wheelchair users

OBJECTIVE

Despite the fact that wheelchair users are exposed to risk factors for neck and upper back pain (NP), little is known about the impact and possible diagnoses associated with NP. The purpose of this study was to examine the significance of NP in wheelchair users and to determine if a portion of the NP may be myofascial in origin.

DESIGN

Cross-sectional cohort study using questionnaires and physical exams to evaluate NP in a convenience sample of wheelchair users from the National Veteran's Wheelchair Games. Main outcome measures included reported NP, visual analog scale of neck complaints, Neck Disability Index, and physical examination findings of trigger points.

RESULTS

Sixty-six percent of subjects reported NP since becoming a wheelchair user and, 60% reported pain during the past month. Neither age nor length of time in a wheelchair was significantly different between those subjects who did and those subjects who did not report pain. Of those respondents who reported NP, 60% visited the doctor about the pain and 40% limited their daily activities due to the pain. Trigger-point palpation reproduced pain in 54% of those respondents who experienced pain in the past month (n = 34).

CONCLUSION

This study provides a first step in defining the prevalence and significance of NP among wheelchair users. Clinicians who work with this population need to ask subjects about symptoms and consider a myofascial origin for that pain when considering treatment.

Gabapentin effect on neuropathic pain compared among patients with spinal cord injury and different durations of symptoms

STUDY DESIGN

This study evaluated the effect of gabapentin on neuropathic pain in patients with spinal cord injury.

OBJECTIVE

To compare the effect of gabapentin on neuropathic pain refractory to conventional analgesics in patients with spinal cord injury and different durations of symptoms.

SUMMARY OF BACKGROUND DATA

Neuropathic pain in patients with spinal cord injury severely compromises their quality of life. Gabapentin is a new antiepileptic drug that may additionally have a role in the treatment of neuropathic pain. So far, there has been little prospective research investigating the effect of gabapentin on neuropathic pain in patients after spinal cord injury or comparing gabapentin-treated patients with varying durations of symptoms after spinal cord injury.

METHODS

The study included 31 patients who had experienced neuropathic pain associated with spinal cord injury or cauda equina syndrome. These subjects were divided into two groups. Group 1 (n = 13) was composed of patients whose duration of pain was less than 6 months, and Group 2 (n = 18) comprised patients whose symptoms of neuropathic pain had lasted more than 6 months. Although these patients had been treated with conventional analgesics such as antidepressants, anticonvulsants, membrane stabilizer, and neuroleptics, they reported that their condition did not improve after a medication trial of at least 2 weeks duration. In this study, conventional analgesics were continued at a therapeutic level, and gabapentin was administrated for an 18-day titration period followed by a 5-week maintenance period at a dosage of 1800 mg/day or the maximum tolerable dosage. The efficacy of gabapentin administration was gauged by a pain score and a sleep interference score using a 100-mm visual analogue scale (VAS) every 2 weeks. The scores of the two groups were compared every 2 weeks over the course of the 8-week study.

RESULTS

The mean pain score and the mean sleep interference score for Group 1 decreased more than that of Group 2 during the interval between 2 to 8 weeks (P < 0.05). The mean pain score for Group 1 decreased from 7.3 +/- 0.5 initially to 3 +/- 0.6 after 8 weeks of treatment, whereas the corresponding score for Group 2 decreased from 7.6 +/- 0.4 to 5.1 +/- 0.6 ( < 0.05). The mean sleep interference score for Group 1 decreased from 5.7 +/- 0.9 initially to 1.8 +/- 0.8 after 8 weeks of treatment, whereas the corresponding score for Group 2 decreased from 5.9 +/- 0.8 to 4.2 +/- 0.7 (P < 0.05). As compared with the onset of this study, a decrease in pain score of 2 or more was reported at the completion of this study for 11 patients (100%) in Group 1 and 10 (71%) of 14 patients in Group 2. A decrease of 2 or more in sleep interference scores was reported for 8 (89%) of 9 patients with sleep interference in Group 1 and for 8 (62%) of 13 patients with sleep interference in Group 2. Some adverse effects such as somnolence were noted, but they were mild or moderate in intensity.

CONCLUSIONS

Gabapentin may be effective in decreasing neuropathic pain refractory to conventional analgesics in some patients with spinal cord injury whose duration of symptoms is less than 6 months, although those with duration of symptoms longer than 6 months showed a significant decrease as well. The drug is unlikely to cause serious adverse effects that limit its use in patients with spinal cord injury.

Chronic pain secondary to disability: a review

BACKGROUND

Until recently, very little has been written regarding chronic pain as a secondary problem in persons who already have a physical disability, despite the potential for pain to increase the negative impact of what may already be a very disabling condition. The purpose of this review is to summarize what is currently known concerning the nature and scope of chronic pain as a secondary condition to disability, specifically spinal cord injury, acquired amputations, cerebral palsy, multiple sclerosis, neuromuscular disease, and postpolio syndrome.

METHOD

What is known concerning the frequency, severity, impact, and treatment of pain in these specific conditions is reviewed, as are the factors that contribute to, or are associated with, adjustment to chronic pain in these disability groups. The authors conclude with several research questions that emerge from this knowledge, the answers to which will contribute to the long-term goal of the reduction of pain and suffering in persons with disabilities.

CONCLUSIONS

The existing literature clearly documents that many persons with disabilities experience chronic pain. Many questions remain unanswered regarding the scope, severity, and treatment of chronic pain in these groups.

Sensory function in spinal cord injury patients with and without central pain

Spinal cord injury (SCI) frequently results in neuropathic pain. However, the pathophysiology underlying this pain is unclear. In this study, we compared clinical examination, quantitative sensory testing (QST) and somatosensory evoked potentials (SEPs) in SCI patients with and without pain below spinal lesion level, with a control group of 20 subjects without injury. All patients had a traumatic SCI with a lesion above T10; 20 patients presented with spontaneous central neuropathic pain below lesion level, and 20 patients had no neuropathic pain or dysaesthesia. Patients with and without pain had a similar reduction of mechanical and thermal detection and pain thresholds, and SEPs. SCI patients with central pain more frequently had sensory hypersensitivity (brush- or cold-evoked pain, dysaesthesia or pinprick hyperalgesia) in dermatomes corresponding to lesion level than SCI patients without pain. There was no difference in intensity of pain evoked by repetitive pinprick at lesion level between patient groups. There was a significant correlation between intensity of brush-evoked dysaesthesia at lesion level and spontaneous pain below lesion level of SCI. These data suggest that lesion of the spinothalamic pathway alone cannot account for central pain in SCI patients, and that neuronal hyperexcitability at injury or higher level may be an important mechanism for pain below injury level.

Interference due to pain following spinal cord injury: important predictors and impact on quality of life

Two studies were designed to examine important predictors of pain following spinal cord injury (SCI), and the impact of pain on self-reported quality of life (QOL). Pain was defined as "interference in day-to-day activities secondary to pain". In order to determine risk factors associated with the development of pain interference, Study 1 examined the predictive validity of multiple demographic, medical, and QOL variables at year 1 post-SCI to self-reported pain interference 2 years post-injury. Results showed that middle age (30-59-year-olds), lower self-reported mental health, and pain interference at 1 year post-SCI were the most important unique predictors of pain interference 2 years post-SCI. In Study 2, participants were separated into four groups; (1) those pain-free at years 1 and 2, (2) those pain-free at year 1 and in pain at year 2, (3) those in pain at year 1 and pain-free at year 2, and (4) those in pain at years 1 and 2. Results showed that only those experiencing a change in pain interference status reported a change in QOL. More specifically, those developing pain interference (group 2) from year 1 to year 2 reported decreased life satisfaction, physical health, and mental health, whereas, those with resolving pain interference from year 1 to year 2 reported an increase in these same domains. Unexpectedly, change in pain interference status was unrelated to change in self-reported handicap. Implications and future directions are discussed.

Self-injurious behavior in children and adolescents with spinal cord injuries

STUDY DESIGN

A case report of self-injurious behavior in four children and adolescents with spinal cord injuries (SCI).

OBJECTIVES

To report a relatively unusual complication of pediatric-onset SCI, focusing on the potential role that dysesthesia may play in self-injurious behavior.

SETTING

A Spinal Cord Injury Program in a Children's Hospital in Chicago that serves children from midwestern and south-central United States of America.

METHOD

Case reports and literature review.

RESULTS

Case reports are presented of four children or adolescents with SCI who exhibited self-injurious behavior. Two of the subjects had symptoms consistent with dysesthesia. The self-injurious behavior in these two subjects and a very young child responded to treatment with anticonvulsants. The self-injurious behavior in the fourth patient was probably the result of poor technique of using his mouth to move his hands, which responded to conservative management including education, occupational therapy and gloves.

CONCLUSION

Self-injurious behavior is a relatively unusual complication of pediatric onset SCI, and may be a manifestation of dysesthesia and be responsive to treatment with anticonvulsants.

Classification of chronic pain associated with spinal cord injuries

OBJECTIVES

To determine interrater reliability of a classification system for chronic pain in persons with spinal cord injury (SCI) and to determine the frequency and characteristics of various pain types as categorized by this system.

DESIGN

Independent categorization (based on questionnaires; for 15 persons, questionnaires plus personal interviews) by 2 investigators.

SETTING

Community.

PARTICIPANTS

A total of 163 individuals aged >or=18 years with SCI and pain.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Pain categories, Short-Form McGill Pain Questionnaire, and Chronic Pain Grade questionnaire.

RESULTS

Among 41 (25%) questionnaires categorized independently by 2 investigators, strength of agreement in categorizing 68 pain problems was substantial (kappa=.68). For 15 persons whose pain was categorized in person by 2 investigators, strength of agreement was also substantial (kappa=.66). Among 163 survey respondents with pain, the most common worst pain was SCI pain (31.9%). Mean characteristic pain intensity +/- standard deviation for worst pain, regardless of type, was 61.02+/-18.5 on a scale from 0 to 100. On average, for worst pain, respondents reported moderate pain-related disability (43.70+/-29.4; scale range, 0-100). Although certain pain descriptors were more often associated with a specific type of pain, none was pathognomonic.

CONCLUSIONS

Substantial interrater reliability was achieved in determining pain categories by use of responses to a questionnaire with a classification system based on presumed pathology. Adding interviews with patients increased our ability to classify pain but did not improve overall interrater reliability.

Pain and rehabilitation after spinal cord injury: the case of sensory spasticity?

Sixty percent of patients with posttraumatic para- or tetraplegia suffer from severe, continuous burning and/or lancinating pain. Multiple sclerosis produces pain in more than 30%. This pain can be as important as the absent mobility or sexual function as a cause of lowered quality of life. Two unique types of longstanding neuropathic pain can be recognized in persons with spinal cord injury: (1). segmentally distributed pain at the lesion; and (2). pain in the body below the lesion, often with late onset. The first type could be produced by nerve root entrapment or by direct segmental deafferentation. The second type probably contains several forms of central pain, evoked either by the original spinal lesion, by an expanding syrinx in the spinal cord or by secondary changes at higher levels of the somatosensory systems. Patients with central pain almost always have stimulus-independent pain. Its intensity may vary independently, be related to the presence of visceral activity/inflammation or be constant. In addition, stimulus-dependent pain is sometimes present, usually because skin areas or viscera below the lesion are allodynic. Partial spinal lesions, especially centrally in the cervical spinal cord, may be more prone to produce pain than are complete lesions. There is limited analgesic effectiveness in controlled studies of serotonin reuptake inhibitors, of sodium channel blockers (lidocaine, tetracaine), of the GABA receptor agonist baclofen (one study) and of the NMDA-receptor antagonist ketamine (one study). There are anecdotal reports on oral carbamazepine, on gabapentin, on intrathecal opiates and also on the alpha(2)-agonist clonidine, being effective in central neuropathic pain. Neurostimulation is effective only if it evokes paraesthesia in the painful area; hence TENS may give relief of segmental pain. Neurodestructive procedures and central neurostimulation have been largely unsuccessful. As in other longstanding pain, improved coping through cognitive-behavioural rehabilitation may be helpful for the clinical outcome.

Anticonvulsants in central pain

Treatment of central neuropathic pain (CP) following lesions of the CNS is a great challenge to the clinician. Preclinical and clinical studies indicate that neuronal hyperexcitability in damaged areas of the central nervous system plays a major role in the development of CP. Anticonvulsants are thought to act by increasing gamma-aminobutyric acid-mediated inhibition, decreasing abnormal neuronal hyperexcitability by modulating sodium and calcium channels or by inhibiting excitatory amino acid actions. The resulting inhibition of excess neuronal activity is thought to be the basis for the use of anticonvulsants in epilepsy as well as neuropathic pain. Both first-generation anticonvulsant drugs (e.g., phenytoin, benzodiazepines, valproate and carbamazepine) and second-generation anticonvulsant drugs (e.g., lamotrigine, gabapentin and topiramate) are used in CP conditions. However, few randomised controlled trials on the treatment of this condition have been published. Present suggestions for anticonvulsant treatment of CP are lamotrigine as the first choice, followed by gabapentin or carbamazepine/oxcarbazepine. These compounds are considered as effective as the antidepressant amitriptyline.

Reliability characteristics of the Donovan spinal cord injury pain classification system

OBJECTIVE

To determine the interrater reliability of the Donovan system for classification of pain in spinal cord injury (SCI) as well as the clinician-based usefulness of each of the classification criteria used in the Donovan system.

DESIGN

Information pertinent to the Donovan system was provided incrementally by videotape for each pain site. After each additional piece of information, the 3 raters classified the pain site into 1 of 5 types and gave a confidence rating (5-point Likert scale) regarding the accuracy of their classifications. Thus, each pain site was classified 6 separate times, each with an associated confidence rating.

SETTING

Academic rehabilitation hospital.

PARTICIPANTS

Twenty-eight persons with traumatic onset SCI reported 60 pain sites.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

The short-form McGill Pain Questionnaire.

RESULTS

Interrater agreement ranged from 50% to 70%. Interrater agreement did not change as additional information was provided. In contrast, confidence ratings significantly increased as additional information was provided.

CONCLUSIONS

There was considerable variability between raters using the Donovan system for classifying SCI pain. Additional clinical information increased the rater's confidence in the accuracy of their ratings but did not improve interrater agreement.

Gabapentin for neuropathic pain following spinal cord injury

STUDY DESIGN

Retrospective review of patient data.

OBJECTIVE

To present two years of experience in the use of gabapentin for the alleviation of neuropathic pain in spinal cord injury patients.

SETTING

Supra-regional Spinal Cord Service, Melbourne, Australia.

METHOD

Data were retrieved from the medical records of all spinal cord injury patients prescribed gabapentin for neuropathic pain. Pain was assessed prior to and during treatment at 1, 3 and 6 months with a 10 cm visual analogue scale which ranged from 0 ('no pain') to 10 ('worst pain imaginable'), or by the documentation of a verbal description of pain.

RESULTS

Seventy-six per cent of patients receiving gabapentin reported a reduction in neuropathic pain. In those patients with data at all four measurement points, the mean pretreatment score was 8.86. Following treatment with gabapentin the score dropped to 5.23, 4.59 and 4.13 at 1, 3 and 6 months, respectively. Where only a verbal description of pain was documented, the trend was that the pretreatment report of 'unbearable' was replaced by 'liveable' during treatment.

CONCLUSION

Our experience suggests that gabapentin offers an effective therapeutic alternative for the alleviation of neuropathic pain following spinal cord injury. Controlled clinical trials are now required to confirm these observations.

Dorsal root entry zone lesioning used to treat central neuropathic pain in patients with traumatic spinal cord injury: a systematic review

STUDY DESIGN

A systematic review was conducted for studies of any design.

OBJECTIVES

To evaluate the effectiveness and safety of dorsal root entry zone lesioning in treating central neuropathic pain of patients with traumatic spinal cord injury.

SUMMARY OF BACKGROUND DATA

Central neuropathic pain has a great impact on the quality of life of many patients with traumatic spinal cord injury. Dorsal root entry zone lesioning has become one of several treatment options. No previous systematic reviews were found that address this indication for the procedure.

METHODS

Several computerized databases were searched along with reference lists of eligible articles and personal files of advisory panel members. Only primary studies of patients older than 13 years with both traumatic spinal cord injury and central neuropathic pain receiving dorsal root entry zone lesioning were included. Two assessors independently performed data extraction and quality assessment for all the studies.

RESULTS

The selection criteria were met by 11 studies. All were case series of 5 to 54 patients. As reported by 10 of the studies, at least 50% of the patients attained more than 50% pain relief or experienced no pain limitation of activity and no need for narcotics. However, all the studies had poorly defined eligibility criteria or none at all, no control groups, and inadequate reporting of adverse effects. Only one study provided adequate patient description. None of the studies reported the validity, reliability, or responsiveness of outcome measures.

CONCLUSIONS

Reviewed studies indicate promising results from dorsal root entry zone lesioning for the treatment of central neuropathic pain in selected patients with traumatic spinal cord injury. However, the strength of the evidence provided by the studies was poor in terms of study design, outcome measures, reports on the severity of adverse effects, patient selection criteria, and patient description. For these reasons, the evidence is weak for the use of dorsal root entry zone lesioning to relieve central neuropathic pain in patients with traumatic spinal cord injury.

Assessment of the impact of pain and impairments associated with spinal cord injuries

OBJECTIVES

To determine the adequacy of the Multidimensional Pain Inventory (MPI) for assessing pain impact after spinal cord injury (SCI) and to determine whether the impact of pain can be separated from other consequences of SCI.

DESIGN

Postal survey.

SETTING

General community.

PARTICIPANTS

Of the 159 subjects contacted who experienced chronic pain, 120 (75.5%) participated.

INTERVENTIONS

Subjects were mailed the original MPI and a set of additional items specific to SCI.

MAIN OUTCOME MEASURE

The MPI.

RESULTS

Confirmatory (CFA) and exploratory factor analyses were performed for each section of the MPI. Elimination of several items, including those related to work in section 1 (pain impact), improved the goodness-of-fit index (GFI). A CFA for section 2 (response of significant other) resulted in acceptable GFI after 2 items were deleted. Decrease in activity levels (section 3) because of other consequences of injury was significantly greater after tetraplegia than after paraplegia. In contrast, pain-related reduction in activities was not associated with injury level. Although other consequences of SCI may have greater impact on activities than pain, severe pain is likely to affect activity levels significantly.

CONCLUSION

The MPI appears to be appropriate for use in a SCI population when modified to eliminate questions related to work and to supplement the activity scale with items addressing decreased activity levels due to pain.

Pain classification following spinal cord injury: the utility of verbal descriptors

OBJECTIVES

To determine the predictive utility of verbal descriptors to distinguish between pain types following spinal cord injury (SCI).

DESIGN

Cross-sectional.

SETTING

USA.

METHODS

Participants (n=29) completed the Short Form - McGill Pain Questionnaire (SF-MPQ) for each pain site reported. A total of 64 pain sites were reported with 80% of the sample reporting multiple pain sites. Each pain site was categorized using three different SCI pain classification schemes. The predictive utility of verbal descriptors to distinguish between pain types was examined statistically using (1) each word separately, (2) a combination of words (ie, the SF-MPQ total subscales, the number of words chosen on each scale), and (3) discriminant function analysis.

RESULTS

There was a substantial overlap in the use of verbal descriptors across pain types. Few differences across pain types were found for endorsement of individual words, and differences across pain types were not found for any of the word combination scores. The majority of the verbal descriptors did not enter the step-wise discriminant functions for each SCI pain classification scheme, however, 'tingling' and 'aching' showed modest predictive utility for neuropathic and musculoskeletal pain, respectively. Correct classification was in the low range (ie, 39% to 82%, average=60%, with a 33% chance level). All three pain classification schemes showed the same general pattern of results.

CONCLUSION

In general, verbal descriptors alone offered marginal utility with regard to identifying specific pain types following SCI. Future directions alone and implications are discussed.

Long-term use of gabapentin for treatment of pain after traumatic spinal cord injury

OBJECTIVE

To determine the long-term efficacy of gabapentin as a treatment of pain after spinal cord injury.

DESIGN

All patients with traumatic-onset spinal cord injury treated with gabapentin were identified and followed up using a longitudinal observational design with two contact points (6 and 36 months after the trial) using a semi-structured interview. The first follow-up interview attempted to capture all 31 patients placed on therapeutic trial. The second follow-up interview attempted to capture those reporting a favorable response (n = 14) to the therapeutic trial at the first follow-up.

RESULTS

Of the 27 patients contacted at the first follow-up (87% response rate), 6 (22%) discontinued the trial secondary to intolerable side effects; therefore, the pain analgesic effects of gabapentin in these patients could not be determined. Of the remaining 21 patients, 14 (67%) reported a favorable response (i.e., a 2 or greater point reduction on a 0-10 pain-rating scale). The second follow-up interview captured 11 (79% response rate) of the 14 patients reporting a favorable response at the first interview, and 91% (10 of 11 patients) continued to report that gabapentin was an effective analgesic. There was no evidence to suggest dosing difficulties due to tolerance over the 3-year period. Sedation, dizziness, and forgetfulness were the most common side effects.

CONCLUSIONS

Gabapentin may be an effective treatment of pain after spinal cord injury among those able to tolerate initial and long-term side effects.

The prevalence and association of neck (coat-hanger) pain and orthostatic (postural) hypotension in human spinal cord injury

OBJECTIVE

To investigate the prevalence of orthostatic (postural) hypotension (OH) and neck pain in a 'coat-hanger' occipito-cervical distribution in subjects with spinal cord injury (SCI), and their association.

METHOD

Blood pressure was measured during head-up tilt to 60 degrees (to determine OH) and neck pain was assessed in 28 subjects with SCI (cervical, thoracic and lumbar level) with McGill Pain Questionnaire, visual analogue scale for pain intensity and Orthostatic Intolerance Symptoms Questionnaire for pain frequency.

RESULTS

Neck pain was reported by 53.6% of subjects. Orthostatic hypotension was present in 57.1% of subjects. Neck pain was reported by 75% of subjects with OH and 25% of subjects without OH (P<0.03, Chi-square). Features of such pain included positive correlation to upright posture and exercise, and relief when lying flat.

CONCLUSION

There is a high prevalence of neck pain and OH in SCI, with a positive association similar to that reported in primary autonomic failure with OH.

Chronic pain after spinal injury: interference with sleep and daily activities

OBJECTIVES

To determine how chronic pain after spinal cord injury (SCI) interfered with sleep, exercise, work, household chores, and other daily activities and to define which clinical aspects of pain and psychosocial factors best predicted the extent of interference.

DESIGN

Postal survey; follow-up to a previous survey conducted 6 months earlier.

SETTING

General community.

PARTICIPANTS

Individuals (n = 217) with traumatic SCI and chronic pain.

INTERVENTION

Subjects answered questions regarding frequency of interference caused by pain on 5 activities: sleep, work, exercise, household chores, and other daily activities. Asked to self-report sadness, fatigue, or anxiety; and to describe location, quality, and intensity of pain.

MAIN OUTCOME MEASURES

Demographic data (gender, age, level of injury); sociodemographic data (education, employment); self-reported psychosocial outlook; clinical characteristics of pain: location (drawing), quality (descriptors), and intensity (2 numeric rating scales). Regression analysis.

RESULTS

The questionnaire was returned by 65.8% of the sample (217/330). A large number of the participants (77.3%) reported frequent interference caused by pain, ie, "often" to "always" in 1 or more of the 5 activities. The combination of high pain intensity and the use of multiple pain descriptors was significantly associated with frequent interference with falling asleep. Frequent sleep interruption was significantly associated with high pain intensity, male gender, anxiety, and higher age at time of injury. In working individuals, frequent interference due to pain was significantly associated with multiple pain descriptors, anxiety, low level of education, and being older at time of injury.

CONCLUSION

Reported extent of pain interference in various areas of activity is related to clinical symptoms of pain as well as to psychologic and psychosocial factors rather than level of injury. The relationship between frequent interference, pain intensity, and multiple descriptors indicate that individuals experiencing several types of pain of high intensity are more likely than others to experience frequent interference with a variety of daily activities including sleep.

Effects of an exercise program on the rehabilitation of patients with spinal cord injury

OBJECTIVES

To evaluate the impact of directed physical exercise in patients with spinal cord injury (SCI) and to measure functional independence before and after an exercise program.

DESIGN

Case series.

SETTING

Tertiary care center.

PARTICIPANTS

Thirteen volunteers with thoracic SCI.

INTERVENTION

Patients participated in a 16-week exercise program, consisting of 3 weekly 120-minute sessions. They performed mobility, strength, coordination, aerobic resistance, and relaxation activities.

MAIN OUTCOME MEASURES

The FIM instrument, arm crank exercise test, wheelchair skills, maximum strength, anthropometry (body composition measurements), and lipid levels. The results were processed by using nonparametric statistical tests.

RESULTS

After comparing the values at the beginning and end of the program, patients showed a significant increase in the following parameters: average FIM score (p < .001) 113 +/- 7.1; weight lifted in the bench press exercise (46%, p < .0001), military press (14%, p < .0002), and butterfly press exercise (23%, p < .0001), and number of repetitions for biceps (10%, p <.0001), triceps (18%, p < .0001), shoulder abductors (61%, p < .0001), abdominals (33%, p <.009), and curl back neck exercise (19%, p < .0001). The maximum resistance achieved during the arm crank exercise test increased (p < .001), and heart rate 6 minutes after the exercise test decreased (p <.05). The time required for the wheelchair skill tests significantly decreased in all the tasks. No statistically significant changes occurred in body weight (p < .154), percentage of body fat (p < .156), lean body weight (p < .158), cholesterol/high-density lipoprotein cholesterol ratio (p < .076), or maximum heart rate (p < .20). The only complication arose in a patient who developed transient sinus bradycardia and hypotension after the arm crank exercise test.

CONCLUSION

The directed exercise program had a positive impact for most of the variables of the study.

Relationships among clinical characteristics of chronic pain after spinal cord injury

OBJECTIVE

To define relationships among various clinical characteristics of pain occurring after spinal cord injury (SCI).

DESIGN

Postal survey.

SETTING

General community.

PARTICIPANTS

Of 330 subjects with SCI reporting chronic pain in a previous survey, 217 volunteered.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Detailed pain history.

RESULTS

Participants had been injured for an average of 8.2 +/- 5.1 years and 55.4% were tetraplegic. Most subjects marked multiple areas on a pain drawing with the back area most frequently (61.8%) indicated. The most common qualities reported were burning pain (59.9%) and aching pain (54.4%). Burning was significantly associated with pain in frontal parts of torso and genitals, buttocks, and lower extremities, whereas aching was significantly associated with neck and shoulders and back. The factor analysis of the relationships between level of injury, location of pain, quality of pain, pain intensity rating, duration of pain breaks, and time for pain onset resulted in 3 groupings: (1) multiple pain locations, burning pain, lower extremity; (2) aching pain, shoulder and neck, cervical injury; and (3) early onset of pain, no breaks to short breaks of pain, and high average pain intensity.

CONCLUSIONS

Relationships among various clinical features of pain after SCI reveal common clinical patterns important for increased understanding of pain mechanisms and for the design of therapeutic interventions for pain management.

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.

Spinal and supraspinal changes in opioid mRNA expression are related to the onset of pain behaviors following excitotoxic spinal cord injury

Excitotoxic spinal cord injury (SCI) causes anatomic, physiologic and molecular changes within the spinal cord and brain. Intraspinal injection of quisqualic acid (QUIS) produces an excitotoxic injury that leads to the onset of behavioral syndromes, believed to be related to the clinical condition of chronic pain. The opioid system, classically involved in the suppression of pain transmission, has been associated with the onset of pain-related behaviors and changes in spinal opioid peptide expression have been demonstrated in various models of SCI and chronic pain. Recently, changes in opioid peptide expression have been demonstrated in both spinal and supraspinal areas following excitotoxic SCI. Therefore, the purpose of this study was to examine changes in opioid peptide gene expression as they relate to the onset of pain behaviors following excitotoxic SCI. Male, Long-Evans rats were given an intraspinal injection of 1.2 microl of 125 mM QUIS and allowed to survive for 10 days, a duration sufficient for the development of pain-related behaviors. Animals were assessed daily for the presence of excessive grooming behavior, i.e. self-directed biting and scratching resulting in damage to superficial and deeper layers of the skin. Animals were also tested for thermal hypersensitivity using a cold plate apparatus on days 5, 7, and 10 following QUIS injection. After sacrifice, quantitative in situ hybridization was performed on regions of the spinal cord surrounding the lesion site as well as whole brain sections through various levels of the thalamus and cortex. Spinal preproenkephalin (PPE) and preprodynorphin (PPD) expression was significantly increased in animals that developed excessive grooming behaviors vs. those that did not. For PPE, this difference was seen bilaterally, in areas of cord caudal to the site of injury. For PPD, this difference was seen only ipsilateral to the site of injection, rostral to the site of injury. In addition, PPE expression in the anterior cingulate cortex and PPD expression in the contralateral parietal cortex were significantly higher in grooming vs. non-grooming animals. These results support previous conclusions that both spinal and supraspinal regulation of endogenous opioid peptide expression plays a role in the response to or onset of post-SCI pain. These results also suggest that the opioid peptides are regulated independently and serve different functions in response to SCI.

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.

The efficacy of intrathecal morphine and clonidine in the treatment of pain after spinal cord injury

We performed a double-blinded, randomized, controlled trial in 15 patients to determine the efficacy of intrathecal morphine or clonidine, alone or combined, in the treatment of neuropathic pain after spinal cord injury. The combination of morphine and clonidine produced significantly more pain relief than placebo 4 h after administration; either morphine or clonidine alone did not produce as much pain relief. In addition, lumbar and cervical cerebrospinal fluid (CSF) concentrations, sampled at these levels at different times after administration were examined for a relationship between pain relief and CSF drug concentration. Lumbar CSF drug concentrations were initially several orders of magnitude larger than those in cervical CSF. After 1-2 h, the concentrations of morphine in cervical CSF markedly exceeded those of clonidine. The concentration of morphine in the cervical CSF and the degree of pain relief correlated significantly. We conclude that intrathecal administration of a mixture of clonidine and morphine is more effective than either drug administered alone and is related to the CSF-borne drug concentration above the level of spinal cord injury. If there is pathology that may restrict CSF flow, consideration should be given to intrathecal administration above the level of spinal cord damage to provide an adequate drug concentration in this region.

Opioid peptide messenger RNA expression is increased at spinal and supraspinal levels following excitotoxic spinal cord injury

Spinal cord injury in rats is known to cause anatomical, physiological and molecular changes within the spinal cord. These changes may account for behavioral syndromes that appear following spinal cord injury, syndromes believed to be related to the clinical condition of chronic pain. Intraspinal injection of quisqualic acid produces an excitotoxic injury with pathological characteristics similar to those associated with ischemic and traumatic spinal cord injury. In addition, recent studies have demonstrated changes in blood flow, neuronal excitability and gene expression in the brain following excitotoxic injury, indicating that behavioral changes may result from modification of neuronal substrates at supraspinal levels of the neuraxis. Because changes in spinal opioid peptide expression have been demonstrated in models of traumatic spinal cord injury and chronic pain, the present study investigated messenger RNA expression of the opioid peptides, preproenkephalin and preprodynorphin, at spinal and supraspinal levels following excitotoxic spinal cord injury. Male, Long-Evans rats were given three intraspinal injections of quisqualic acid (total 1.2 microl, 125mM). After one, three, five, seven or 10days, animals were killed and quantitative in situ hybridization performed on regions of the spinal cord surrounding the lesion site, as well as whole-brain sections through various levels of the thalamus. Preproenkephalin and preprodynorphin expression was increased in spinal cord areas adjacent to the site of quisqualic injection and in cortical regions associated with nociceptive function, preproenkephalin in the cingulate cortex and preprodynorphin in the parietal cortex, both ipsilaterally and contralaterally at various time-points following injury. These results further our knowledge of the secondary events that occur following spinal cord injury, specifically implicating supraspinal opioid systems in the CNS response to spinal cord injury.

Gabapentin for chronic pain in spinal cord injury: a case report

A 30-year-old white woman with an L1 complete spinal cord injury (SCI) secondary to a gunshot wound in 1985, presented to a chronic pain service for evaluation. She had a 13-year history of chronic lower extremity pain. She described her discomfort as "throbbing, aching, and stabbing." She had tried many different medications, including opioids, Tegretol, and tricyclic antidepressants, without success. During the evaluation process, she admitted to being "angry, frustrated, and anxious." She was diagnosed with central pain after SCI. She was placed on gabapentin 300 mg 3 times daily; within 1 week, her visual analog pain scale fell from 95 mm to 27 mm, and her McGill Short Form pain score fell from 13 to 3. Her mood also vastly improved. This case report suggests that gabapentin should be studied as a therapeutic option for treating central pain post-SCI and should be considered as a viable, well-tolerated, low-toxicity tool.

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.

Acute care management of spinal cord injuries

Meeting the health care needs of the spinal cord-injured patient is an immense challenge for the acute care multidisciplinary team. The critical care nurse clinician, as well as other members of the team, needs to maintain a comprehensive knowledge base to provide the care management that is essential to the care of the spinal cord-injured patient. With the active participation of the patient and family in care delivery decisions, the health care professionals can help to meet the psychosocial and physical needs of the patient/family unit. This article provides an evidence-based, comprehensive review of the needs of the spinal cord-injured patient in the acute care setting including optimal patient outcomes, methods to prevent complications, and a plan that provides an expeditious transition to rehabilitation.