Distinctive Patterns of sonographic Nerve Enlargement between acquired Axonal and Demyelinating Neuropathies. (S42.002)

OBJECTIVE: We systematically investigated main arm and leg nerves in patients with CIDP, MIDN, MMN and acquired axonal neuropathy to determine whether nerve sonography is able to discriminate between acquired axonal and demyelinating neuropathies. BACKGROUND: Sonographic detection of morphologic abnormalities in polyneuropathies is a relatively new research area. However, no systematic investigation has been performed yet. DESIGN/METHODS: We recruited 40 patients with various acquired axonal neuropathies, 26 with CIDP, 8 with MIDN and 14 with MMN. Medical Research Council sum-score was determined. A standardized sonographic protocol was applied. We evaluated nerve size and vascularization in median, ulnar, fibular and posterior tibial nerves as well as brachial plexus were bilaterally. We also quantitatively assessed fascicle size and echogenicity. RESULTS: All 88 patients demonstrated nerve enlargement, yet only few revealed increased vascularization on enlarged nerves. Demyelinating neuropathies revealed larger nerves than axonal neuropathies, especially proximal to sites of entrapment (median and ulnar nerve, brachial plexus p 10 mm 2 with a sensitivity of 93[percnt] and specificity of 88[percnt], ulnar nerve at upper arm a cut-off value of > 10 mm 2 with a sensitivity of 49[percnt] and specificity of 99[percnt], superior truncus of brachial plexus cut-off value of > 8 mm 2 with a sensitivity of 43[percnt] and specificity of 99[percnt]. The swelling ratio was greater in axonal than in demyelinating neuropathies at median, ulnar and fibular nerve (p<0.001). Nerve hypertrophy did not correlate with age, gender, MRC sum-score (overall nor that of median, ulnar or fibular nerve innervated muscles). CONCLUSIONS: In demyelinating neuropathies enlargement of nerves is multifocal among multiple nerves, whereas in axonal neuropathies it is restricted to sites of entrapment. Nerve sonography is able to discriminate between acquired axonal and demyelinating neuropathies. Disclosure: Dr. Goedee has nothing to disclose. Dr. Van Asseldonk has nothing to disclose. Dr. Van den Berg has received personal compensation for activities with Baxter, Biogen Idec, and Cytokinetics. Dr. Visser has nothing to disclose.