Polyneuropathies and chronic inflammatory demyelinating polyradiculoneuropathy in multiple sclerosis

Background: Polyneuropathies co-occurring with multiple sclerosis (MS) may be underdiagnosed while causing additional disability burden.

Objective: To determine polyneuropathy presence and type in MS and compare MS with chronic inflammatory demyelinating polyradiculoneuropathy (MS-CIDP) versus MS with other non-inflammatory polyneuropathies.

Methods: Retrospective chart review of Mayo Clinic cases diagnosed with MS and polyneuropathy. Serum from MS-CIDP for pan-IgG autoantibodies to neurofascin-155 were tested when available.

Results: From 1980-2013, 133 co-existing MS/ polyneuropathy cases were identified. Twenty-eight MS patients had inflammatory neuropathy (11 CIDP, 5 plexopathy, 2 vasculitis, 4 monoclonal gammopathy-associated, 6 other), 15 inherited neuropathy (8 axonal, 7 demyelinating), 32 diabetic sensorimotor polyneuropathy, and 58 other. 109 had neuropathy beginning simultaneous to or after MS diagnosis (82%). Compared to MS cases with other polyneuropathy subtypes, MS-CIDP cases had absent or reduced ankle reflexes (100 vs. 70%, p = 0.04), earlier age of neuropathy recognition (52 vs. 58 years, p = 0.048), worse impairment (NIS 27 vs. 22 points, p < 0.03), and more acquired demyelinating electrophysiology features (46% vs. 9%, p < 0.003). Of MS-CIDP cases with available serum, 1-in-3 had IgG4 autoantibodies to neurofascin-155.

Conclusion: (1) Polyneuropathies occurring in MS contribute to neurological disability. (2) Diagnosing polyneuropathies in people with MS is challenging and, likely, under-diagnosed. Recognition is important as some polyneuropathies (e.g., CIDP) are treatable. (3) The probable over-representation of inflammatory neuropathy (especially CIDP) in MS suggests a shared dysimmune pathogenesis, supported by autoantibodies to neurofascin-155.