• Alessia Peretti, Giovanna Squintani, Federica Taioli, Matteo Tagliapietra, Tiziana Cavallaro, and Gian M Fabrizi.
• Department of Neurology, Ospedale San Bortolo, Azienda ULSS8 Berica, Vicenza, Italy.
• Eur J Pain. 2022 Apr 1; 26 (4): 929-936.

BackgroundPain, either nociceptive or neuropathic (NP), is a common symptom in Charcot-Marie-Tooth (CMT) disease.MethodsWe investigated small fibers involvement and its correlation with pain in different CMT subtypes through a systematic clinical and neurophysiological study. We enrolled 50 patients: 19 with duplication of PMP22 (CMT1A), 11 with mutation of MPZ (CMT1B, CMT2I/J, or CMTDID), 12 with mutation of GJB1 (CMTX1), and 8 with mutation of MFN2 (CMT2A and CMT2A2B). Pain was rated with the 11-point Numerical Rating Scale and characterized through Neuropathic Pain Symptoms Inventory. Laser-evoked potentials (LEPs) were recorded after right foot and hand stimulation and N2-P2 complex amplitude and latency were compared with those of 41 controls.ResultsOverall pain prevalence was 36%. NP was present in 14.6% of patients, with a length-dependent distribution in 85.7% of cases, and it was significantly more frequent in CMT1A (p < 0.001). Aδ fibers involvement greatly varies between CMT subtypes, reflecting differences in molecular pathology and pathophysiologic mechanisms. Prolonged N2 latency from foot stimulation was noted in 11 CMT1A patients, 5 of which report NP. MPZ-CMTs displayed different neurophysiological phenotypes and a very low prevalence of NP. LEPs were normal in all but one CMTX1 patients, although lower limbs N2-P2 amplitude was significantly reduced in males (p = 0.043). MFN2-CMTs were NP free and LEPs recordings were all normal. NP strictly correlated with LEPs alterations (p = 0.017).ConclusionsNP prevalence varies among CMTs subtypes and is mainly related to Aδ fibers impairment.SignificanceNeuropathic pain is a frequent finding in Charcot-Marie Tooth disease and is related to Aδ fibers impairment. Patients at higher risk are those belonging to certain genetic subtypes (i.e. CMT1A and CMT2J) or with laser-evoked potentials abnormalities. While managing this disease, clinicians should be aware of this symptom in order to offer best treatment options to their patients.© 2022 European Pain Federation - EFIC®.

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