Identifying clinical neuropathic pain phenotypes is a first step to better understand the underlying pain mechanisms after spinal cord injury (SCI). The primary purpose of the present study was to characterize multidimensional neuropathic pain phenotypes based on quantitative sensory testing (QST), pain intensity, and utilization of catastrophizing coping strategies. Thermal perception, thermal pain, and vibratory perception thresholds were assessed above and below the level of injury (LOI) in 101 persons with SCI and neuropathic pain, 18 persons with SCI and no neuropathic pain, and 50 able-bodied, pain-free controls. Cluster analysis of QST z-scores below the LOI, pain intensity ratings, and the Coping Strategies Questionnaire (CSQ) catastrophizing subscale scores in subjects with neuropathic pain resulted in two phenotypes: severe neuropathic pain (SNP) with greater pain intensity (7.39 ± 1.57) and thermal and vibratory sensitivity compared with the moderate neuropathic pain (MNP; 5.40 ± 1.43). A factor analysis including all CSQ subscales, the Neuropathic Pain Symptom Inventory (NPSI) total score, and thermal pain sensitivity above and below the LOI resulted in three factors: (1) adaptive pain coping including increasing activities, diverting attention, and reinterpreting pain sensations; (2) catastrophizing, neuropathic pain, and thermal sensitivity including greater NPSI total score, thermal pain sensitivity below the LOI, and catastrophizing; and (3) general pain sensitivity including greater thermal pain sensitivity above the LOI and lower catastrophizing. Our results suggest that neuropathic pain symptom severity post-SCI is significantly associated with residual spinothalamic tract function below the LOI and catastrophizing pain coping.

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.

Many everyday tasks cannot be accomplished without adequate grip strength, and corticomotor drive to the spinal motoneurons is a key determinant of grip strength. In persons with tetraplegia, damage to spinal pathways limits transmission of signals from motor cortex to spinal motoneurons. Corticomotor priming, which increases descending drive, should increase corticospinal transmission through the remaining spinal pathways resulting in increased grip strength. Since the motor and somatosensory cortices share reciprocal connections, corticomotor priming may also have potential to influence somatosensory function. The purpose of this study was to assess changes in grip (precision, power) force and tactile sensation associated with two different corticomotor priming approaches and a conventional training approach and to determine whether baseline values can predict responsiveness to training. Participants with chronic (≥1 year) tetraplegia (n = 49) were randomized to one of two corticomotor priming approaches: functional task practice plus peripheral nerve somatosensory stimulation (FTP + PNSS) or PNSS alone, or to conventional exercise training (CET). To assess whether baseline corticospinal excitability (CSE) is predictive of responsiveness to training, in a subset of participants, we assessed pre-intervention CSE of the thenar muscles. Participants were trained 2 h daily, 5 days/week for 4 weeks. Thirty-seven participants completed the study. Following intervention, significant improvements in precision grip force were observed in both the stronger and weaker hand in the FTP + PNSS group (effect size: 0.51, p = 0.04 and 0.54, p = 0.03, respectively), and significant improvements in weak hand precision grip force were associated with both PNSS and CET (effect size: 0.54, p = 0.03 and 0.75, p = 0.02, respectively). No significant changes were observed in power grip force or somatosensory scores in any group. Across all groups, responsiveness to training as measured by change in weak hand power grip force was correlated with baseline force. Change in precision grip strength was correlated with measures of baseline CSE. These findings indicate that corticomotor priming with FTP + PNSS had the greatest influence on precision grip strength in both the stronger and weaker hand; however, both PNSS and CET were associated with improved precision grip strength in the weaker hand. Responsiveness to training may be associated with baseline CSE.

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.