OBJECTIVE: Chronic inflammatory demyelinating polyradiculoneuropathies (CIDP)
with antibodies against neurofascin 155 (Nfasc155) or contactin-1 (CNTN1) have
distinctive clinical features. Knowledge on their electrophysiological
characteristics is still scarce. In this study, we are investigating whether
these patients have specific electrophysiological characteristics.
METHODS: The electrophysiological data from 13 patients with anti-Nfasc155 IgG4
antibodies, 9 with anti-CNTN1 IgG4 antibodies were compared with those of 40
consecutive CIDP patients without antibodies.
RESULTS: All the patients with antibodies against Nfasc155 or CNTN1 fulfilled the
EFNS/PNS electrodiagnostic criteria for definite CIDP. There was no
electrophysiological difference between patients with anti-CNTN1 and
anti-Nfasc155 antibodies. Nerve conduction abnormalities were heterogeneously
distributed along nerves trunks and roots. They were more pronounced than in CIDP
without antibodies. Motor conduction velocity on median nerve <24 m/s or motor
velocity on ulnar nerve <26 m/s or motor distal latency on ulnar nerve >7.4 ms
were predictive of positive antibodies against the node of Ranvier with a
sensitivity of 59% and a specificity of 93%.
CONCLUSIONS: Marked conduction abnormalities may suggest the presence of positive
antibodies against the node of Ranvier.
SIGNIFICANCE: Anti-Nfasc155 and anti-CNTN1 antibodies target the the paranodal
axo-glial domain but are associated with nerve conduction abnormalities mimicking
a "demyelinating" neuropathy.