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We aim to draw clinical-neurophysiological correlations in our cohort of patients affected by IgM-related neuropathy to investigate whether neurophysiological parameters may help differentiate the classical phenotype from atypical forms. We retrospectively evaluated patients with IgM-related neuropathy referred to our Institute from 1990 to 2011. All patients underwent extensive laboratory, clinical and neurophysiological evaluation. A classic sensory-ataxic form was observed in 20 of 34 patients, while an atypical phenotype (multiple mononeuropathy, polyneuropathy with predominant motor impairment, painful small-fibre neuropathy) was identified in the remaining 14 cases. Nerve conduction studies revealed in almost all cases a pattern typical of demyelination. Terminal latency index and distal motor latency of median nerve, distal motor latency and motor conduction velocity of peroneal nerve when recorded from extensor digitorum brevis, were significantly associated with classic sensory-ataxic phenotype. Conversely, a compound muscle action potential amplitude reduction of peroneal nerve from the tibialis anterior, was mostly associated with atypical forms. No clear electrophysiological differences between classical forms and atypical cases can be identified in IgM-related neuropathy. Still, we demonstrated that demyelinating abnormalities are more often associated with classical phenotypes, while axonal impairment occurs more often in atypical clinical patterns. Performing correlations between clinical and neurophysiological findings in IgM-related neuropathy may help to better understand different disease mechanisms in this heterogeneous form of inflammatory neuropathy.

Objective : To evaluate the occurrence of nerve entrapment syndrome in chronic inflammatory demyelinating polyneuropathy (CIDP). Methods : We retrospectively evaluated neurophysiologic results of 41 (25 male and 16 female, mean age 49.8, range 11–87) patients with CIDP. We evaluated the frequency of focal neurophysiologic lesion at entrapment site distinguishing two kinds of lesion: (a) true entrapment; and (b) false entrapment on the basis of nerve conduction results. Results : Occurrence of focal aggression within the entrapment site is similar to that out of the entrapment site in all examined nerves. Conclusions : The entrapment sites are not an elective zone of focal autoimmune aggression in CIDP. Therefore, in CIDP patients a true entrapment, neurophysiologically demonstrated, could be a concomitant pathology and if a severe and persistent entrapment worsens functional deficit and symptoms, a surgical decompression could be useful.

We studied patients with neuropathy and anti-myelin-associated glycoprotein antibodies nerve ultrasound (US). 28 patients with anti-MAG neuropathy underwent nerve US. Echotexture, nerve cross sectional area (CSA), intra-nerve and inter-nerve CSA variability were assessed. Patients with IgM paraproteinemic neuropathy without anti-MAG antibodies and with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) associated with IgM paraprotein were studied as controls. US findings were correlated with disease duration and clinical severity (INCAT disability score). 26/28 patients had increased CSA (23 at atleast one nerve outside entrapment sites). Intra-nerve CSA variability was abnormal in 21/28 patients (in 14 for increased nerve CSA outside entrapment sites). Inter-nerve CSA variability was abnormal in 16 patients (in half of whom for CSA increase out of entrapment sites). No correlation was found between US findings and INCAT disability score or disease duration. Patients with IgM paraproteinemic neuropathy without anti-MAG antibodies had similar US abnormalities. Instead 4/5 patients with CIDP and IgM paraprotein presented significant and diffuse nerve CSA enlargement. The US findings in anti-MAG antibody neuropathy, different from those of CIDP, might express the diverse pathogenic mechanisms and contribute to diagnosis in atypical cases.