Charcot-Marie-Tooth disease--muscle biopsy findings in relation to neurophysiology

Nine patients with Charcot-Marie-Tooth disease with reduced motor nerve conduction velocity (MNCV), i.e. type 1 (CMT1), demyelinating form, and nine patients with Charcot-Marie-Tooth disease with normal or near-normal MNCV, i.e. type 2 (CMT2), axonal form, were subjected to percutaneous muscle biopsy from the anterior tibial muscle in order to characterize histopathological abnormalities and evaluate differences between the two groups. Data from the biopsies were compared with those from 18 age- and sex-matched healthy controls. Muscle biopsies from the CMT1 patients exhibited angular atrophic fibres that were scattered or in small groups, findings commonly described as neuropathic. Muscle biopsies from the CMT2 patients exhibited atrophic fibres that were rounded or elongated in groups and hypertrophic fibres with central nuclei and fibre splitting. There were also increased amounts of connective tissue, 'whorled fibres', degeneration and signs of regeneration, findings commonly regarded as myopathic. In conclusion, muscle biopsies from patients with CMT1 and CMT2 showed markedly different histopathological abnormalities. Possible underlying mechanisms are discussed.