Asymmetric Acquired Demyelinating Polyneuropathies: MMN and MADSAM

Area of Science:

• Neurology
• Clinical Neuroscience
• Immunology

Background:

• The clinical spectrum of chronic acquired demyelinating polyneuropathies (CADP) has evolved since the initial description of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).
• Current understanding categorizes CADP based on distinct clinical presentations, moving beyond a singular definition of CIDP.

Purpose of the Study:

• To delineate the expanded spectrum of chronic acquired demyelinating neuropathies.
• To differentiate between subtypes of CADP, including CIDP, multifocal motor neuropathy (MMN), and multifocal acquired demyelinating sensory and motor neuropathy (MADSAM).
• To highlight the pragmatic reasons for distinguishing these clinical entities based on presentation and treatment response.

Main Methods:

• Review and synthesis of existing clinical descriptions and classifications of CADP.
• Comparative analysis of clinical features, diagnostic criteria, and treatment responses across different CADP subtypes.

Main Results:

• CIDP is now reserved for symmetric, generalized weakness presentations.
• Asymmetrical, multifocal forms include MMN (motor only) and MADSAM (sensory and motor involvement).
• MMN typically shows resistance to corticosteroids, with IVIg as a first-line treatment, while MADSAM may respond to prednisone or IVIg, similar to CIDP.

Conclusions:

• Splitting CADP into distinct entities like CIDP, MMN, and MADSAM is clinically pragmatic.
• Recognizing subtype differences is essential for optimizing diagnostic and therapeutic strategies in demyelinating neuropathies.
• Treatment approaches vary significantly, necessitating accurate classification for effective patient management.