Validation of the nerve axon reflex for the assessment of small nerve fibre dysfunction

Objective: To validate nerve–axon reflex-related vasodilatation as an objective method to evaluate C-nociceptive fibre function by comparing it with the standard diagnostic criteria. Methods: Neuropathy was evaluated in 41 patients with diabetes (26 men and 15 women) without peripheral vascular disease by assessing the Neuropathy Symptom Score, the Neuropathy Disability Score (NDS), the vibration perception threshold (VPT), the heat detection threshold (HDT), nerve conduction parameters and standard cardiovascular tests. The neurovascular response to 1% acetylcholine (Ach) iontophoresis was measured at the forearm and at both feet by laser flowmetry. An age-matched and sex-matched control group of 10 healthy people was also included. Results: Significant correlations were observed between the neurovascular response at the foot and HDT (rs = −0.658; p