TRANSLATIONAL RESEARCH SECTION Original Research Article Sensory Small Fiber Function Differentially Assessed with Diode Laser (DL) Quantitative Sensory Testing (QST) in Painful Neuropathy (PN)

Sensory function of small peripheral nerve fiber was assessed by means of quantitative sensory testing (QST) during which sensory stimulation was pro- vided using diode laser (DL) in patients suffering from painful neuropathy (PN) and compared with symptom-free healthy controls (HC). Based on pre- vious research work using DL stimulation, param- eters that demonstrated safe and specific activation of A-delta, which were distinct from stimulation parameters for the activation of C-fibers, were uti- lized in this study. Results of this study demon- strated that this differential activation pointed to the impaired function of A-delta fibers while C-fiber function was unaffected. Stimulation of HC repro- duced previously published results, and stimulation during this study was safe also without any dermal effect in patients with PN and in HC. Parameters used in this study were demonstrated in previous preclinical rodent study identical differential effect on activation of A-delta and C-fibers, and as such, DL is an ideal tool for translational pain research where specific activation of A-delta or C-fibers, or both, is required.