Quantitative sensory testing of temperature thresholds: Possible biomarkers for persistent pain?

OBJECTIVE: To investigate the reproducibility of thermal thresholds, as measured by repeated quantitative sensory testing (QST) in healthy controls, and to asses if temperature sensitivity differs between healthy controls and a cohort of patients with persistent pain. SUBJECTS: A total of 54 healthy controls were compared with 25 consecutive patients selected for pain rehabilitation by multidisciplinary assessment teams. METHODS: Heat and cold detection and pain thresholds in the forearm and neck were determined by QST. Reproducibility was evaluated by 2 consecutive tests 6-9 months apart. RESULTS: Thermal detection and pain thresholds were reproducible in a subgroup of 20 healthy controls. The patients had slightly increased heat and cold detection thresholds, but significantly lower thresholds for cold and heat pain. The most clear-cut differences between patients and healthy controls were observed for cold pain thresholds. Calculation of the differences between thermal detection and pain thresholds (delta values) further strengthened the differences between patients and healthy controls. CONCLUSION: Thermal detection and pain thresholds are reproducible over time, allowing longitudinal assessment of sensory function using QST. Although increased sensitivity to cold pain was the most prominent finding in this cohort of patients with persistent pain, calculation of the differences between thermal detection and pain thresholds may prove superior in detecting sensory alterations.