[Ultrasonographic diagnosis of demyelinating neuropathy]

Ultrasonographic nerve enlargement has been reported in patients with demyelinating Charcot-Marie-Tooth disease, chronic inflammatory demyelinating polyneuropathy, multifocal motor neuropathy and POEMS (polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes) syndrome. Reference nerve sizes are needed at evaluation sites to determine nerve enlargement. However, neither site-based differences nor associations between the reference nerve sizes and several physical characteristics had been sufficiently verified. In our study, the reference nerve sizes of the median and ulnar nerves and the cervical nerve roots were determined in healthy Japanese adults. Site-based differences in the nerve sizes were observed. The stratification of reference nerve sizes according to gender is reasonable for practical use, as these differences reflect physical characteristics. The cross-sectional areas of the peripheral nerves were markedly larger at all evaluation sites in patients with demyelinating CMT than in patients with CIDP. However, the nerve sizes of the cervical nerve roots were not significantly different between patients with either disease. We also observed that the number of sites exhibiting nerve enlargement in the intermediate region of the median and ulnar nerves was useful to distinguish demyelinating CMT from CIDP. Thus, nerve ultrasonography is a promising diagnostic supportive tool for demyelinating neuropathy.