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.