title: Laser Doppler imaging in the detection of peripheral neuropathy.
abstract: Small fiber neuropathy is common in a number of systemic diseases and is often challenging to diagnose. Laser Doppler imaging (LDI) is a test of small fiber neurovascular function that can quantify the integrity of the vasomotor C-fiber mediated axon-reflex, but no standardized method of analysis exists. We developed a novel LDI analysis technique and tested it in a human model of small fiber neuropathy. Eighteen healthy subjects (age 24 ± 3 years) underwent LDI testing to assess the axon-mediated flare area in response to 10% acetylcholine iontophoresis. LDI measurements were taken before and longitudinally after a 48-hour application of 0.1% capsaicin (to cause a transient small fiber neuropathy) on the skin of the thigh; placebo cream was placed on the contralateral thigh as a control. We compared our new LDI image analysis technique to two previously published methods. The new LDI analysis technique was the only method to show a consistent difference in axon-reflex area between capsaicin treated and placebo treated skin on all testing days (p<0.05) with maximum attenuation of the flare area immediately post-application (438 ± 298 mm(2) vs. 824 ± 375 mm(2), p<0.05). In conclusion, this study demonstrates that our novel flare area method for LDI analysis can detect neurovascular dysfunction in a model of small fiber neuropathy, is an improvement over existing methods, and may supplement clinical assessment of small fiber neuropathy.
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Ben M W
authors.initials: BM
authors.lastname: Illigens
authors.forename: Timo
authors.initials: T
authors.lastname: Siepmann
authors.forename: Joseph
authors.initials: J
authors.lastname: Roofeh
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Gibbons
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D017078:Laser-Doppler Flowmetry / Q000379:methods*; D008137:Longitudinal Studies; D008297:Male; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis* / Q000503:physiopathology*; D055815:Young Adult
keywords: Capsaicin; Iontophoresis; LDI; Laser Doppler imaging; Small fiber neuropathy; Vasomotor axon-reflex