Analysis of sensory function in Charcot-Marie-Tooth disease

Ten patients each with Charcot-Marie-Tooth disease type 1 (CMT1), demyelinating form, and CMT2, axonal form, were subjected to analysis of sensory function including sensory screening and quantitative determination of thermal, thermal pain and vibratory thresholds in hands and feet. The threshold values were compared with data from age- and sex-matched control groups. All patients had a symmetrical sensory dysfunction, which was most prominent in the lower extremities. Temperature was the modality most often affected on screening and on quantitative determination of thresholds in both CMT1 and CMT2 patients. Mean thermal thresholds were significantly increased in both hands and feet in CMT1 as well as in CMT2 patients when compared with controls. There was no statistically significant difference between thermal thresholds in the CMT1 and CMT2 patients. Mean thermal pain thresholds were significantly increased in the feet of the CMT2 patients when compared with the controls and they were significantly higher in the hands of the CMT2 than in the CMT1 patients. Vibratory thresholds (VT) were abnormal in all CMT1 patients and in a majority of the CMT2 patients. Mean VT was significantly increased in hands and feet of both CMT1 and CMT2 patients when compared with the controls and the mean VT was significantly higher in the feet of the CMT1 than in the CMT2 patients. The difference with an increased heat pain threshold in the CMT2 patients and an increased VT in the CMT1 patients is suggested to be due to demyelination in CMT1 leading to affection of sensory function mediated by myelinated nerve fibres and to axonal disturbance in CMT2 with affection of sensory function mediated by small diameter myelinated and unmyelinated C-fibres.