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Relationships between sensory function and chronic pain in spinal cord injury
Elizabeth Roy Felix, PhD1, Yenisel Cruz-Almeida, MSPH2, Alan R. Rosales2, and Eva Widerström-Noga, DDS, PhD1. (1) Office of Research and Development, Department of Veterans Affairs Medical Center, 1201 NW 16th St., Miami, FL 33125, (2) The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, P.O. Box 016960, R-48, Miami, FL 33101
Chronic neuropathic pain in persons with spinal cord injuries (SCI) is a common problem that is often refractory to treatment. There is growing interest in methods [such as quantitative sensory testing (QST)] that have potential for identifying the pathophysiological mechanisms responsible for the generation and maintenance of SCI-related pain. Thus, there is a need to determine the validity and reliability of QST in the evaluation of SCI-related neuropathic pain. The main objective of the present study was to determine the relationship between QST measures and clinical characteristics associated with neuropathic pain. Thresholds for light touch, vibration, cool and warm detection, and cold and hot pain were measured at a number of test sites above, at, and below the level of injury in painful and non-painful areas in a sample of people with SCI and neuropathic pain. Comparisons were made between “low neuropathic pain” subjects and “high neuropathic pain” subjects based on a median split for scores on the Neuropathic Pain Symptom Inventory. Cool detection and cold pain thresholds were significantly higher (p<.001, uncorrected) for “high neuropathic pain” subjects. Likewise, all other thresholds were higher for subjects with high neuropathic pain, although statistical significance was not reached (p between .01 and .08, uncorrected). QST has potential as an integral part of a comprehensive evaluation protocol for SCI-related pain by providing invaluable insights regarding the mechanisms involved in the development and/or maintenance of neuropathic pain. Further research is needed to conclusively determine the ability of these methods to reliably diagnose the specific underlying mechanisms that could provide a basis for individually tailored treatments and improved management of SCI-related pain.
