In chronic inflammatory demyelinating polyradiculopathy (CIDP), the impairment of unmyelinated nerve fibers appears unexpected. The measurement of the electrically induced axon flare reflex is a clinical test to assess the peripheral C-nociceptor function. In this study, we compared the flare area in patients suffering from CIDP with healthy subjects.
We examined 18 patients fulfilling the criteria for CIDP (11 men, mean age 51.8 years, SD 15.1) and 18 age-matched adult healthy volunteers (control group) (11 men, mean age 51.9 years, SD 15.8). The flare responses were elicited by transcutaneous electrical stimulation and recorded by laser Doppler imaging.
There was a significant reduction of electrically induced maximum flare area in the foot dorsum of patients with CIDP (t-value 2.08, P = 0.04) which proved to be length-dependent measured by a numerical index comparing the results with the forearm and thigh. The repeatedmeasures ANOVA revealed statistically significant smaller flare areas in all body regions for the CIDP group (P < 0.001).
The axon flare reaction to electrical stimulation was decreased in patients with chronic demyelinating inflammatory polyneuropathy. The evaluation of the axon flare response can be proposed as a noninvasive objective functional test to detect an impaired C-fiber function in CIDP patients with the advantages of simplicity of the procedure, time economy, and objectivity.
*Laboratory of Electromyography and Clinical Neurophysiology, Department of Neurology, Aeginition Hospital, University of Athens, Athens, Greece;
†Department of Anesthesiology and Intensive Care Medicine, Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany; and
‡Department of Neurology, University Clinic of Würzburg, Würzburg, Germany.
Address correspondence and reprint requests to Aikaterini E. Papagianni, MD, University Clinik of Wuerzburg, Wuerzburg, Germany; e-mail: Papagianni_A@ukw.de.
The authors declare no conflicts of interest.
Supported in part by the special account for research grants of the National and Capodistrian University of Athens, Greece.