Polyneuropathy With Motor Conduction Block in POEMS

Area of Science:

• Neurology
• Clinical Electrophysiology

Background:

• POEMS syndrome is a paraneoplastic syndrome linked to plasma cell disorders.
• Polyneuropathy in POEMS syndrome often exhibits demyelinating features.
• Motor conduction block (CB) is typically associated with CIDP, not POEMS syndrome.

Purpose of the Study:

• To determine the frequency of motor CB in patients diagnosed with POEMS syndrome.
• To highlight the importance of identifying CB in POEMS syndrome for differential diagnosis.

Main Methods:

• Retrospective analysis of clinical and electrophysiological data.
• Inclusion of seven POEMS syndrome patients examined between August 2017 and December 2022.
• Performance of 28 upper extremity motor nerve conduction studies.

Main Results:

• Partial motor CB was detected in 25% of upper extremity motor nerves studied (7 out of 28 nerves).
• Six out of seven patients exhibited motor CB.
• One patient presented with motor CB in both median and ulnar nerves.

Conclusions:

• Motor CB may be a more common electrophysiological finding in POEMS syndrome than previously recognized.
• Accurate identification of CB is vital for distinguishing POEMS syndrome from CIDP, which have different treatment protocols.
• Further research with larger patient cohorts is warranted to confirm these findings.