Spasticity and Pain after Spinal Cord Injury: Impact on Daily Life and the Influence of Psychological Factors.

BACKGROUND: Spasticity and pain frequently co-occur in persons with spinal cord injury (SCI), yet, how these sequelae interact in daily life is unclear. Additionally, little is known about how psychological factors relate to the perception of spasticity and its impacts on daily life. OBJECTIVES: (1) Characterize relationships between spasticity and chronic pain with regard to perceived severity, difficulty dealing, and life interference. (2) Determine the extent to which perceived spasticity severity and physiological, psychological, and pain-related factors contribute to impacts of spasticity on daily life (difficulty in dealing, life interference). (3) Determine the effects of painful spasticity on aspects of chronic pain and spasticity (severity, life interference, interference with sleep, and spasm duration). DESIGN: Observational study. SETTING: University laboratory. PARTICIPANTS: Twenty participants with SCI and lower extremity spasticity. METHODS: Measures included International SCI Pain Basic Data Set, Pain and Spasticity Inventories, Difficulty Dealing with Pain/Spasticity, SCI-Spasticity Evaluation Tool, Connor-Davidson Resilience and Moorong Self-Efficacy Scales, Spinal Cord Assessment Tool for Spastic Reflexes, spasm duration, and injury-related and demographic factors. Bivariate correlations, multiple regression analyses, and pairwise comparisons were performed. RESULTS: Spasticity and chronic pain were directly related, with respect to perceived severity, difficulty dealing, and life interference (rho = 0.514-0.673, P < .05). Shorter injury duration, greater perceived spasticity severity, and greater difficulty dealing with pain explained 61% of variance in difficulty dealing with spasticity. Greater perceived spasticity severity and lower resilience explained 72% of variance in life interference of spasticity. Spasm duration was not significantly associated with perceived spasticity severity. Participants with painful spasticity had significantly greater chronic pain severity (P = .02) and sleep-related impact of spasticity (P = .03) than participants without painful spasticity. CONCLUSIONS: Perceived severity of spasticity, injury duration, ability to deal with chronic pain, resilience, and painful spasms appear to play important roles in the negative impacts of spasticity on life after SCI. LEVEL OF EVIDENCE: III.

Impact of spasticity on transfers and activities of daily living in individuals with spinal cord injury.

CONTEXT/OBJECTIVE: For persons with spinal cord injury, spasticity commonly interferes with activities of daily living such as transfers. Electromyography can be used to objectively measure muscle spasms during transfers, but how electromyographic measures relate to the impact spasticity has on life, or to clinically-rated spasticity, is unclear. We aimed to characterize relationships among spasm duration and magnitude, impact of spasticity on daily life, and a clinical measure of extensor spasticity, as well as to determine reliability of the electromyographic measures. DESIGN: Participants (N=19) underwent electromyographic measurements of involuntary muscle activity (spasm duration and magnitude) evoked in quadriceps muscles during transfers on two days. Impact of spasticity on daily life was measured with the Spinal Cord Injury Spasticity Evaluation Tool. Clinically-rated spasticity severity was measured with the Spinal Cord Assessment Tool for Spastic reflexes. RESULTS: No significant associations were found between impact of spasticity and spasm duration, spasm magnitude, or clinical extensor spasticity score. Absolute and normalized spasm duration were positively associated with clinical extensor spasticity score (rho=0.510-0.667, P < 0.05). Spasm measures during transfers had good to excellent day-to-day reliability (rho=0.656-0.846, P < 0.05). CONCLUSIONS: Electromyographic and clinical measures of involuntary activity in the lower extremity do not significantly relate to perceived impact of spasticity on daily life. However, quadriceps spasm duration during transfers is related to clinically-rated extensor spasticity. Electromyography is a reliable method of quantifying quadriceps spasms during transfers. Future investigations should identify factors that influence the impact of spasticity on life, which may help direct treatment strategies to reduce problematic impact.

Decreased spinothalamic and dorsal column medial lemniscus-mediated function is associated with neuropathic pain after spinal cord injury.

Neuropathic pain (NP) after spinal cord injury (SCI) can significantly and negatively affect quality of life and is often refractory to currently available treatments. In order to find more effective therapeutic avenues, it would be helpful to identify the primary underlying pathophysiological mechanisms in each individual. The aim of the present study was to assess the relationship between the presence and severity of NP after SCI and measures of somatosensory function mediated via the dorsal column medial lemniscal (DCML) pathway and the spinothalamic tract (STT). Vibratory, mechanical, thermal, and pain thresholds measured in areas at and below the neurological level of injury (LOI) in persons with SCI and NP (SCI-NP, n=47) and in persons with SCI without NP (SCI-noNP, n=18) were normalized to data obtained from able-bodied pain-free control subjects (A-B, n=30). STT-mediated function at and below the LOI was significantly impaired in both SCI groups compared with A-B controls (p<0.001), but not significantly different between the two SCI groups (NP vs. no-NP). In contrast, the SCI-NP group had significantly greater impairment of DCML-mediated function at the LOI, as reflected by greater vibratory detection deficits (z=-3.89±0.5), compared with the SCI-noNP group (z=-1.95±0.7, p=0.034). Within the SCI-NP group, NP severity was significantly associated with increased thermal sensitivity below the LOI (r=0.50, p=0.038). Our results suggest that both impaired STT and DCML-mediated function are necessary for the development of NP after SCI. However, within the SCI-NP group, greater NP severity was associated with greater sensitivity to thermal stimuli below the LOI. This finding concurs with other studies suggesting that STT damage with some sparing is associated with NP.

Pain symptom profiles in persons with spinal cord injury.

OBJECTIVE: Persistent pain is a common consequence of spinal cord injury. A patient-specific assessment that combines both the identification of pain symptoms and psychosocial factors is needed for a tailored treatment approach. The aim of the study was to define pain symptom profiles and to determine their relationship with psychosocial factors in persons with spinal cord injury. DESIGN: Face-to-face interview and examination. SETTING: VA Medical Center and Miami Project to Cure Paralysis, Miami, Florida. PATIENTS: Persons with spinal cord injury (135 men and 21 women) provided detailed descriptions of 330 neuropathic pains. OUTCOME MEASURES: The American Spinal Injury Impairment Scale, pain history and measures of pain interference, life satisfaction, locus of control, social support and depression. RESULTS: The exploratory factor analyses and regression analyses revealed three distinct symptom profiles: 1) aching, throbbing pain, aggravated by cold weather and constipation predicted by a combination of chance locus of control and lower levels of life satisfaction; 2) stabbing, penetrating, and constant pain of high intensity predicted by a combination of pain interference, localized pain, powerful others locus of control and depressed mood; and 3) burning, electric, and stinging pain aggravated by touch and muscle spasms predicted by pain interference. CONCLUSIONS: Although these results need to be replicated in other spinal cord injury samples, our findings suggest that pain symptom profiles may be a useful way to further characterize pain in a comprehensive assessment strategy.

Biopsychosocial perspective on a mechanisms-based approach to assessment and treatment of pain following spinal cord injury.

This article applies a biopsychosocial perspective to a mechanisms-based approach to the assessment and treatment of the heterogeneous and persistent pain conditions associated with spinal cord injury (SCI). This article presents an overview of the types of pains experienced after SCI and some of the research on the mechanisms, diagnostic issues, and psychosocial factors relevant for the development of treatments targeting specific underlying mechanisms of pain. This review also discusses several diagnostic challenges of determining the underlying causes of pain in each individual patient.

Relationship between pain characteristics and pain adaptation type in persons with SCI.

After a spinal cord injury (SCI), people commonly experience several types of persistent pain. Unfortunately, individuals who experience unremitting pain despite various treatments have no choice but to adapt to their pain. Although people may possess different styles of pain adaptation, one can hypothesize that the specific types of pain a person experiences are also important. The present study determined the association between pain characteristics and specific adaptational patterns to pain after SCI. Participants (N = 182) were interviewed regarding pain characteristics and the impact of pain on their psychosocial status. Based on the SCI version of the Multidimensional Pain Inventory (MPI-SCI), they were classified as Dysfunctional, with higher pain severity (PS) and life interference (LI); Interpersonally Supported, with moderately high PS, high social support levels, and less LI; or Adaptive Coper, with lower PS and LI levels. A multinomial logistic regression analysis indicated a robust model fit (chi-square = 63.6, p < 0.0005), predicting MPI-SCI subgroup membership based on a combination of pain intensity (p < 0.0005), extent of pain aggravation (p < 0.01), electric quality of pain (p < 0.01), constancy of pain (p < 0.01), and distribution of pain (p < 0.05). The results of the present study support the biopsychosocial model of pain.

Reliability and validity of quantitative sensory testing in persons with spinal cord injury and neuropathic pain.

Quantitative sensory testing (QST) has been used to assess neurological function in various chronic pain patient populations. In the present study, we investigated the ability of QST to reliably characterize somatosensory dysfunction in subjects with spinal cord injury (SCI) and neuropathic pain by measuring mechanical, vibration, and thermal detection and pain thresholds. Test-retest reliability was determined based on data collected from 10 subjects with SCI and neuropathic pain who underwent QST on two occasions approximately 3 weeks apart. The intraclass correlation coefficients for mechanical, vibration, warm, and cool detection thresholds were in the "substantial" range, while thresholds for cold pain and hot pain demonstrated "fair" stability in this sample of patients. To determine the validity of QST in persons with SCI-related neuropathic pain, we evaluated the relationship between somatosensory thresholds and severity of neuropathic pain symptoms with multiple linear regression analysis. Thermal pain threshold was the only QST variable significantly related to the severity of neuropathic pain symptoms. The present study provides preliminary evidence that QST is a reliable and valid adjunct measurement strategy for quantifying the neurological dysfunction associated with neuropathic pain in persons with SCI.

Psychosocial subgroups in persons with spinal cord injuries and chronic pain.

OBJECTIVES: To define adaptational subgroups in people with chronic pain and spinal cord injury (SCI), and to compare these subgroups with respect to demographic factors, level of injury, functional independence, pain disability, depressed mood, social support, and life satisfaction. DESIGN: Interviews. SETTING: Veterans Affairs medical center and The Miami Project to Cure Paralysis. PARTICIPANTS: Persons with SCI and chronic pain (N=190). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: The Multidimensional Pain Inventory, SCI version. RESULTS: Cluster analysis revealed 3 subgroups: (1) dysfunctional (34.6% of all participants), characterized by higher pain severity, life interference, and affective distress scores, and lower levels of life control and activities scores; (2) interpersonally supported (33.0% of participants), characterized by moderately high pain severity, and higher life control, support from significant others, distracting responses, solicitous responses, and activities scores; and (3) adaptive copers (32.4% of participants), characterized by lower pain severity, life interference, affective distress, support from significant others, distracting responses, solicitous responses, activities and higher life control scores. Compared with the dysfunctional subgroup, the interpersonally supported subgroup reported significantly greater social support and life satisfaction and less pain disability and emotional distress, despite moderately high pain severity. CONCLUSION: Three subgroups, independent of sex, pain duration, and functional status, were identified. Although severe pain significantly decreases life satisfaction after SCI, its impact is moderated by perceived social support.

Chronic pain after spinal cord injury: what characteristics make some pains more disturbing than others?

Different types of pain are often present in the same individual with spinal cord injury (SCI). Relieving the most disturbing of these pains may substantially affect quality of life. Persons with SCI and chronic pain (n = 194) completed a structured interview that detailed the characteristics of each pain they experienced. Pairwise analyses revealed that the following characteristics were more common among the most disturbing pains: "sharp"; "stabbing"; located at the level of injury; frequently aggravated; and having high intensity, unpleasantness, constancy, interference, and neuropathic pain-like features. A conditional logistic regression analysis showed that the combination of "sharp" and high pain intensity, interference, aggravation, and constancy significantly predicted the most disturbing pain (p < 0.001). This study suggests that, in addition to pain intensity, factors such as interference, quality, aggravation, and constancy of pain are important to consider when one evaluates SCI-related pain, since these symptoms may indicate pains that are particularly disturbing to an individual with SCI.

Internal consistency, stability, and validity of the spinal cord injury version of the multidimensional pain inventory.

OBJECTIVE: To evaluate the internal consistency, stability, and construct validity of a spinal cord injury (SCI) version of the Multidimensional Pain Inventory (MPI-SCI). DESIGN: Interview. SETTING: Veterans Affairs medical center and university-based institute. PARTICIPANTS: Community sample of persons with SCI and chronic pain (N=161). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: The MPI-SCI. RESULTS: The internal consistency of the MPI-SCI subscales ranged from fair (.60) for affective distress to substantial (.94) for pain interference with activities. The subscales of the MPI-SCI (ie, life interference [r=.81], affective distress [r=.71], solicitous responses [r=.86], distracting responses [r=.85], general activity [r=.69], pain interference with activities [r=.78], pain severity [r=.69], negative responses [r=.69]) showed adequate stability. In contrast, the stability of the support (r=.59) and the life control subscales (r=.31) was unacceptably low. All MPI-SCI subscales with the exception of the perceived responses by significant others subscales showed good convergent, discriminant, and concurrent validity. CONCLUSIONS: The MPI-SCI appears to be a reasonable measure for evaluating chronic pain impact after SCI. In clinical trials, however, supplementary instruments should be included to assess changes in affect, social support, and perceptions of life control.

Chronicity of pain associated with spinal cord injury: A longitudinal analysis.

This study determined the stability of self-reported clinical pain characteristics and pain-induced interference with sleep and daily activities in people with spinal cord injury. The study followed up a previous survey that identified clinical pain patterns (i.e., neuropathic pain below the level of injury; upper-limb pain in tetraplegia; and severe, persistent pain). A confirmatory factor analysis (CFA) of the present study's data confirmed the previously observed pain patterns. The CFA also confirmed positive correlations between the surveys on individual pain characteristics (i.e., number of pain locations [r = 0.63, p < 0.001], number of descriptors [r = 0.61, p < 0.001], pain intensity [r = 0.68, p < 0.001], and temporal aspects [r = 0.47, p < 0.001]). Despite an overall stable clinical picture of pain, "aching" pain (p < 0.001) and sleep interference caused by pain (p < 0.001) significantly increased over time.

Psychosocial profiles of people with pain associated with spinal cord injury: identification and comparison with other chronic pain syndromes.

OBJECTIVES: The objectives of the study were to: (1) identify psychosocial profiles of people with pain associated with spinal cord injuries (SCI), and (2) compare the psychosocial profiles with other chronic pain syndromes. METHODS: History questionnaires and the Multidimensional Pain Inventory (MPI) were mailed to 159 persons with chronic pain and SCIs (SCICP) and 120 (75.5%) agreed to participate. RESULTS: Cluster analysis of MPI scores identified 2 subgroups of SCICP. One (42.5%) was characterized by high Pain Severity (PS), Affective Distress (AD), Life Interference (LI), and low Life Control (LC) similar to a previously identified cluster labeled Dysfunctional. The second (57.5%) was characterized by low PS, AD, LI, and high levels of LC and activity (GA), similar to the Adaptive Copers (AC) cluster identified in previous studies with the exception that the scores were lower on Support (S), Solicitous Responses (SR), and Negative Responses (NR) and higher on Distracting Responses (DR). Both subgroups were similar to those observed in other chronic pain syndromes (CPSs). People with SCIs differed significantly from heterogeneous chronic pain and chronic headaches in that they indicated less inference of pain with activities. They also scored lower on S. SCICP reported comparable levels of LI, LC, AD, S, SR, but greater levels of PS compared with a group of people with post-polio syndrome. DISCUSSION: The similarities and differences between SCI and other CPSs suggest that although a general measure assessing psychosocial impact can be used across pain syndromes, it is important to use different norms for comparison of particular pain syndromes. The failure to identify a subgroup of patients characterized by low levels of S and high levels of NR, and the low SR and DR for SCICP compared with other CPSs warrants examination.

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).

Proton magnetic resonance spectroscopy of the thalamus in patients with chronic neuropathic pain after spinal cord injury.

BACKGROUND AND PURPOSE: Spinal cord injury (SCI) results in a number of consequences; one of the most difficult to manage is chronic neuropathic pain. Thus, defining the potential neural and biochemical changes associated with chronic pain after SCI is important because this may lead to development of new treatment strategies. Prior studies have looked at the thalamus, because it is a major sensory relay station. The purpose of our study was to define alterations in metabolites due to injury-induced functional changes in thalamic nuclei by using single-voxel stimulated echo acquisition mode MR spectroscopy. METHODS: Twenty-six men were recruited: 16 patients with SCI and paraplegia (seven with pain, nine without pain) and 10 healthy control subjects. Pain was evaluated in an interview, which included the collection of information concerning the location, quality, and intensity of pain, carefully identifing the dysesthetic neuropathic pain often seen in SCI. Localized single-voxel (8-cm(3) volume) proton spectra were acquired from the left and right thalami. RESULTS: The concentration of N-acetyl (NA) was negatively correlated with pain intensity (r = -0.678), and the t test showed that NA was significantly different between patients with pain and patients without pain (P =.006). Myo-inositol was positively correlated with pain intensity (r = 0.520); difference between patients with pain and those without pain was almost significant (P =.06). CONCLUSION: The observed differences in metabolites in SCI patients with and pain and in those without pain suggest anatomic, functional, and biochemical changes in the thalamic region.

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.