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 provided using diode laser ( DL ) in patients suffering from painful neuropathy ( PN ) and compared with symptom‐free healthy controls ( HC ). Based on previous research work using DL stimulation, parameters that demonstrated safe and specific activation of A ‐delta, which were distinct from stimulation parameters for the activation of C ‐fibers, were utilized in this study. Results of this study demonstrated that this differential activation pointed to the impaired function of A ‐delta fibers while C ‐fiber function was unaffected. Stimulation of HC reproduced 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.