Nodal Conduction Block and Internodal Conduction Block in Nodopathy

Area of Science:

• Neurology
• Immunology
• Electrophysiology

Background:

• Nodopathy, a neuropathy linked to autoantibodies at the node of Ranvier, requires precise electrophysiologic characterization.
• New terms, nodal conduction block (CB) and internodal CB, were introduced to describe distinct electrophysiologic patterns.

Approach:

• A systematic review analyzed 35 cases (23 acute, 12 chronic) of nodopathy identified via PubMed.
• Inclusion criteria included positive nodal antibody tests and detailed nerve conduction data.
• Cases were classified based on the presence of nodal or internodal CB.

Key Points:

• Nodal CB, defined as CB without temporal dispersion or slow nerve conduction velocity, was observed in 61% of acute nodopathy cases.
• Internodal CB, characterized by temporal dispersion and/or slow nerve conduction velocity, was present in 52% of acute and 100% of chronic nodopathy cases.
• Mixed CB patterns were also noted in acute nodopathy.

Conclusions:

• Nodal CB is the hallmark electrophysiologic finding in acute nodopathy.
• Internodal CB is characteristic of chronic nodopathy, though it can also occur in acute cases.
• These electrophysiologic distinctions are crucial for diagnosing and understanding nodopathies.