Classification of chronic pain associated with spinal cord injuries

Pain following spinal cord injury

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

Chronic neuropathic pain: mechanisms, drug targets and measurement

Neuropathic pain is common in many diseases or injuries of the peripheral or central nervous system, and has a substantial impact on quality of life and mood. Lesions of the nervous system may lead to potentially irreversible changes and imbalance between excitatory and inhibitory systems. Preclinical research provides several promising targets for treatment such as sodium and calcium channels, glutamate receptors, monoamines and neurotrophic factors; however, treatment is often insufficient. A mechanism-based treatment approach is suggested to improve treatment. Valid and reliable tools to assess various symptoms and signs in neuropathic pain and knowledge of drug mechanisms are prerequisites for pursuing this approach. The present review summarizes mechanisms of neuropathic pain, targets of currently used drugs, and measures used in neuropathic pain trials.

Pain after spinal cord injury: an evidence-based review for clinical practice and research. Report of the National Institute on Disability and Rehabilitation Research Spinal Cord Injury Measures meeting

BACKGROUND/OBJECTIVES

To examine the reliability, validity, sensitivity, and practicality of various outcome measures for pain after spinal cord injury (SCI), and to provide recommendations for specific measures for use in clinical trials.

DATA SOURCES

Relevant articles were obtained through a search of MEDLINE, EMBASE, CINAHL, and PubMed databases from inception through 2006.

STUDY SELECTION

The authors performed literature searches to find articles containing data relevant to the reliability and validity of each pain outcome measure in SCI and selected non-SCI populations.

DATA EXTRACTION

After reviewing the articles, an investigator extracted information utilizing a standard template. A second investigator reviewed the chosen articles and the extracted pertinent information to confirm the findings of the first investigator.

DATA SYNTHESIS

Taking into consideration both the quantity and quality of the studies analyzed, judgments on reliability and validity of the measures were made by the two investigators. Based upon these judgments, recommendations were formulated for use of specific measures in future clinical trials. In addition, for a subset of measures a voting process by a larger group of SCI experts allowed formulation of recommendations including determining which measures should be incorporated into a minimal dataset of measures for clinical trials and which ones need revision and further validity and reliability testing before use.

CONCLUSIONS

A 0-10 Point Numerical Rating Scale (NRS) is recommended as the outcome measure for pain intensity after SCI, while the 7-Point Guy/Farrar Patient Global Impression of Change (PGIC) scale is recommended as the outcome measure for global improvement in pain. The SF-36 single pain interference question and the Multidimensional Pain Inventory (MPI) or Brief Pain Inventory (BPI) pain interference items are recommended as the outcome measures for pain interference after SCI. Brush or cotton wool and at least one high-threshold von Frey filament are recommended to test mechanical allodynia/hyperalgesia while a Peltier-type thermotester is recommended to test thermal allodynia/hyperalgesia. The International Association for the Study of Pain (IASP) or Bryce-Ragnarsson pain taxonomies are recommended for classification of pain after SCI, while the Neuropathic Pain Scale (NPS) is recommended for measuring change in neuropathic pain and the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) for quantitating neuropathic and nociceptive pain discrimination.

Shoulder pain following tetraplegia: a follow-up study 2–4 years after injury

OBJECTIVES

To investigate (1) the characteristics of shoulder pain following discharge from rehabilitation for tetraplegia, (2) the relationship between pain and any associated risk factors and (3) the relationship between pain and functional activities, and pain and quality of life.

DESIGN

Longitudinal study.

SETTING

Spinal Injuries Unit, Australia.

METHODS

Participants (n=27) were surveyed between 2 and 4 years postinjury. Prospective data on shoulder pain during rehabilitation had been collected previously and allowed comparison with the follow-up data. Data collected included pain intensity and quality, the Wheelchair User's Shoulder Pain Index (WUSPI) and perceived effect of pain on quality of life.

RESULTS

Shoulder pain prevalence was 70%. Pain was associated with discharge motor level of C6-T1 (P=0.003). Pain was most commonly located in the shoulder joint. Pain was primarily aggravated by movement and cold weather and relieved by rest. The most painful activity was lifting an object from overhead. Quality of life was affected by pain in 68.4% of participants.

CONCLUSION

Shoulder pain is common following rehabilitation for tetraplegia and is associated with injury level. Pain is reported during daily tasks and adversely affects quality of life. Areas for further research are identified.

Pain Interference in Persons With Spinal Cord Injury: Classification of Mild, Moderate, and Severe Pain

Pain intensity is commonly measured by patient ratings on numerical rating scales (NRS). However, grouping such ratings into categories may be useful for guiding treatment decisions or interpreting clinical trial outcomes. The purpose of this study was to examine pain intensity classification in 2 samples of persons with spinal cord injuries (SCI) and chronic pain. The first sample (n = 307) rated the average intensity and activity interference of pain in general, and the second sample (n = 174) rated their worst pain problem. Pain intensity was categorized as mild, moderate, or severe using 4 possible classification systems; analyses were performed to determine the classification system that best distinguished the pain intensity groups in terms of activity interference. In both samples, the optimal mild/moderate boundary was lower (mild = 1-3 on a 0-10 NRS scale) than that reported previously for individuals with other pain problems. The possibility that pain may interfere with activity at lower levels for individuals with SCI requires further exploration. The moderate/severe boundary suggested by previous research was confirmed in only one of the samples. Implications for the assessment of pain intensity and functioning in persons with SCI and pain are discussed.

PERSPECTIVE

Although pain in individuals with SCI is common, more research is needed regarding its characteristics and treatment. This study sought to develop an empirically based classification system for mild, moderate, and severe pain that could be useful for applying clinical treatment guidelines and for interpreting the results of much-needed clinical trials.

Reliability of the Bryce/Ragnarsson spinal cord injury pain taxonomy

BACKGROUND/OBJECTIVE

Pain is a common secondary complication of spinal cord injury (SCI). However, the literature offers varying estimates of the numbers of persons with SCI who develop pain. The variability in these numbers is caused in part by differences in the classification of pain; there is currently no commonly accepted classification system for pain affecting persons after SCI. This study investigated the interrater reliability of the Bryce/Ragnarsson SCI pain taxonomy (BR-SCI-PT). The hypothesis was that, when used by physicians with minimal training in the BR-SCI-PT, it would have high interrater reliability for the categorization of reported pains.

METHODS

One hundred thirty-five vignettes, each of which described a person with SCI with one or more different etiologic subtypes of pain, were evaluated by 5 groups of up to 10 physicians with SCI subspecialization (39 respondents total). Physician classifications were compared with those made by the investigators.

RESULTS

Of 179 pain descriptions, 83% were categorized correctly to one of the 15 BR-SCI-PT pain types; 93% were categorized correctly with respect to level (above/at/below neurological level of injury), whereas 90% were categorized correctly as being either nociceptive or neuropathic. Subjects expressed a generally high confidence in the correctness of their classifications.

CONCLUSIONS

Substantial interrater agreement was achieved in determining subtypes of pain within the BR-SCI-PT. The agreement was improved for categorizing within less restrictive categories (ie, with respect to the neurological level of injury and whether the pain was nociceptive or neuropathic).

Gastrointestinal symptoms related to autonomic dysfunction following spinal cord injury

The impact of spinal cord injury on an individual's gastrointestinal tract function is often poorly understood by the general public and also by those involved with persons with spinal cord injury. This chapter reviews the anatomy, physiology and function of the gastrointestinal tract, with particular emphasis on neurological control mechanisms. In turn, it relates the effect that spinal cord injury has on the neurological control of the gastrointestinal tract. The symptoms that are encountered by patients in the acute phase following injury, and by individuals in the months/years after injury, with particular reference to the effect of altered autonomic nervous system control of the gastrointestinal tract, are discussed. Together with a following summary of current bowel management regimens and techniques, this chapter aims to provide an overall view of the effect that autonomic dysfunction due to spinal cord injury has on gastrointestinal function.

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

BACKGROUND/OBJECTIVE

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

DESIGN

Postal survey.

SETTING

Community.

PARTICIPANTS

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

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSIONS

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

A survey of chronic pain in the pediatric spinal cord injury population

BACKGROUND/OBJECTIVE

Although several reports characterize pain associated with adult-onset spinal cord injury (SCI), little is known about the incidence and etiology of pain associated with pediatric-onset SCI. The purpose of this study was to assess the incidence and type of chronic pain in the pediatric SCI population and to evaluate the resulting impact on activities of daily living (ADLs).

METHODS

Patients attending clinic in a pediatric tertiary care facility in a major metropolitan area having sustained an SCI during childhood were asked to participate. Participants were assessed using the Adolescent Pediatric Pain Tool and the Lansky Play Performance Scale, 2 standardized assessments of pain and function, respectively. In addition, a questionnaire designed to characterize the population and the types of pain reported was administered.

RESULTS

Thirty-one participants were enrolled with an age range at the time of injury from 5 months to 18 years. Of this population, 65% reported chronic pain. The pain reports were classified as either nocioceptive (48%) or neuropathic (19%). Interference with ADLs and play was present in only 1 participant.

CONCLUSION

Based on these pilot data, pain associated with a pediatric-onset SCI is common. The incidence of pain in this study approached the reported incidence of chronic pain in adult-onset SCI. In the present population, nocioceptive pain was more common than was neuropathic pain. These data suggest that although common, chronic pain associated with childhood SCI has a significantly smaller impact on daily activities than that reported in the literature for adult-onset SCI.

Describing pain with physical disability: Narrative interviews and the McGill Pain Questionnaire

OBJECTIVES

To identify common pain descriptors used by people with physical disability-related pain and to suggest words that are likely to prompt responses in clinical interviews and assessments.

DESIGN

Open-ended interviews were coded and then contrasted with responses to a pain questionnaire, obtained through mail or interview surveys.

SETTING

Rehabilitation research program.

PARTICIPANTS

Twenty-eight people with physical disability-related pain in a series (n=54) of in-depth interviews and 1053 participants with disabilities who responded to mailed questionnaires or structured interviews about pain and its impact (459 with acquired lower-limb amputation, 471 with spinal cord injury, 123 with cerebral palsy).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Pain interview descriptions and McGill Pain Questionnaire (MPQ).

RESULTS

Different pain experiences were reflected in narrative descriptions and self-report questionnaire responses. We report the common terms, but across diagnoses use of terms does not appear to clearly differentiate distinct pain phenomenon. Narrative interviews support the use of several MPQ pain descriptors. However, discrete descriptors are recommended when assessing adults with physical disability.

CONCLUSIONS

We identified pain descriptors that appear to be most useful in assessing daily life and participation experiences with physical disability-related pain. These may be clinically useful, but caution is advised when doing diagnostic workups based solely on sensory and affective pain descriptions.

Exacerbation of Chronic Pain following Spinal Cord Injury

Because of the high prevalence and the refractory nature of pain following spinal cord injury (SCI), it is important to increase the understanding of what factors aggravate different types of pain. This information is related to pain generating mechanisms and may thus be useful in the diagnosis and management of these difficult pain conditions. The aims of the present study were to (1) identify variables (factors) that exacerbate chronic pain associated with SCI and (2) define the relationships among these patterns of pain exacerbation, specific pain characteristics, and psychological features. A sample out of 159 (75.5%) people with SCI and chronic pain, volunteered to participate in a mail survey. Over 50% of the sample indicated that prolonged sitting, infections, fatigue, muscle spasms, cold weather, and sudden movements exacerbated their pain. A principal components analysis detected five sets of factors that were reported to magnify pain: negative mood, prolonged afferent activity (bowel, bladder, somatic), weather, voluntary physical activity, and transient somatic afferent activity. Negative mood and prolonged afferent activity were frequently and significantly associated with both pain characteristics and psychosocial issues. A multiple regression analysis revealed that a combination of decreased activity levels due to pain (t = 3.54; p < 0.001), pain located in the frontal aspects of torso (including genitals) (t = 2.29; p < 0.05), "burning" (t = 2.26; p < 0.05), or "electric" (t = 2.09; p < 0.05) pain, and a limited perception of life control (t = -2.16; p < 0.05) was significantly associated with a high extent of pain aggravation (R2 = 0.39; p < 0.000).