Neurophysiological assessments of pathophysiology in autoimmune nodopathies

Abstract

Autoimmune nodopathies associated with IgG4 autoantibodies against neurofascin155 (NF155), contactin1 (CNTN1) and contactin–associated protein1 (Caspr1) were divided from chronic inflammatory demyelinating polyneuropathy (CIDP) since 2021. These conditions do not show apparent pathological demyelination, but show detachment of paranodal myelin loops from axolemma. Nerve conduction studies in autoimmune nodopathies showed conduction slowing in the demyelinating range in the distal and intermediate sites of the peripheral nerves. Neurophysiological characteristics of anti–CNTN1 nodopathy was acute or subacute axonal degeneration. Anti–NF155 autoimmune nodopathy frequently showed relatively lower amplitude tibial nerve compound muscle action potentials compared with those in upper limbs, which supposes length–dependent peripheral neuropathy. In contrast, the feature of “sural sparing sensory responses” which indicates non–length dependent neuropathy was also frequently observed. These findings might indicate the specific pathophysiology in autoimmune nodopathies associated with IgG4 autoantibodies.