psd-502 and Small-Fiber-Neuropathy

Topical application of lidocaine-and-prilocaine (LP) cream attenuates the functionality of small cutaneous nerve fibers. The aim of this human study was to measure the underlying excitability modulation of small cutaneous nerve fibers using a novel and fast perception threshold tracking (PTT) technique.. Small sensory fibers were selectively blocked by 120-minute topical application of LP and confirmed by quantitative sensory testing. Excitability changes of small (activated by a specially designed pin electrode) and large (patch electrode) nerve fibers were assessed as the strength-duration relation and threshold electrotonus.. The excitability assessed by the strength-duration relation and threshold electrotonus was significantly modulated for the small afferents (P < 0.05, Wilcoxon's test) but not the large afferents.. This novel PTT technique was able to assess inhibition of membrane properties of small cutaneous fibers, suggesting the usefulness of the technique as a diagnostic method for assessing impairment of small fibers, as seen in many types of polyneuropathies.

Topics: Administration, Cutaneous; Adult; Anesthetics, Local; Cross-Over Studies; Double-Blind Method; Electric Stimulation; Electrodiagnosis; Female; Healthy Volunteers; Humans; Lidocaine, Prilocaine Drug Combination; Male; Nerve Fibers, Myelinated; Nerve Fibers, Unmyelinated; Sensory Thresholds; Small Fiber Neuropathy; Young Adult