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Pure motor onset and IgM-Gammopathy occurrence in multifocal acquired demyelinating sensory and motor neuropathy


Beecher, G and Shelly, S and Dyck, PJB and Mauermann, ML and Martinez-Thompson, JM and Berini, SE and Naddaf, E and Shouman, K and Taylor, BVM and Dyck, PJB and Engelstad, J and Howe, Benjamin M and Mills, JR and Dubey, D and Spinner, RJ and Klein, CJ, Pure motor onset and IgM-Gammopathy occurrence in multifocal acquired demyelinating sensory and motor neuropathy, Neurology, 97, (14) pp. 1-12. ISSN 0028-3878 (2021) [Refereed Article]

DOI: doi:10.1212/WNL.0000000000012618


Objectives: To longitudinally investigate patients with multifocal acquired demyelinating sensory and motor (MADSAM) neuropathy, quantifying timing and location of sensory involvements in motor-onset patients, along with clinico-histopathological and electrophysiological findings to ascertain differences in patients with and without monoclonal gammopathy of uncertain significance (MGUS).

Methods: Patients with MADSAM neuropathy seen at Mayo Clinic and tested for monoclonal gammopathy and ganglioside antibodies, were retrospectively reviewed (January 1st, 2007-December 31st, 2018).

Results: Of 76 patients with MADSAM, 53% had pure motor, 16% pure sensory, 30% sensorimotor and 1% cranial nerve onsets. Motor-onset patients were initially diagnosed as multifocal motor neuropathy (MMN). MGUS occurred in 25% (89% IgM subtype), associating with ganglioside autoantibodies (p<0.001) and higher IgM titers (p<0.04). Median time to sensory involvements (confirmed by electrophysiology) in motor-onset patients was 18 months (range: 6-180). Compared to initial motor nerve involvements, subsequent sensory findings were within the same territory 35% (14/40), outside 20% (8/40), or both 45% (18/40). Brachial and lumbosacral plexus MRI was abnormal in 87% (34/39) and 84% (21/25), respectively, identifying hypertrophy and increased T2 signal predominantly in brachial plexus trunks (64%), divisions (69%), and cords (69%), and intrapelvic sciatic (64%) and femoral (44%) nerves. Proximal fascicular nerve biopsies (n=9) more frequently demonstrated onion-bulb pathology (p=0.001) and endoneurial inflammation (p=0.01) than distal biopsies (n=17). MRI and biopsy findings were similar amongst patient subgroups. Initial Inflammatory Neuropathy Cause and Treatment (INCAT) disability scores were higher in patients with MGUS relative to without (p=0.02). Long-term treatment responsiveness by INCAT score reduction ≥1 or motor Neuropathy Impairment Score (mNIS) >8 point reduction occurred in 75% (49/65) irrespective of MGUS or motor-onsets. Most required ongoing immunotherapy (86%). Patients with MGUS more commonly required dual-agent immunotherapy for stability (p=0.02).

Discussion: Pure motor-onsets are the most common MADSAM presentation. Long-term follow-up, repeat electrophysiology and nerve pathology help distinguish motor-onset MADSAM from MMN. Better long-term immunotherapy responsiveness occurs in motor-onset MADSAM compared to MMN reports. Patients having MGUS commonly require dual immunotherapy.

This study provides Class II evidence that most clinical, electrophysiological, and histopathological findings were similar between patients with MADSAM with and without monoclonal gammopathy of unknown significance.

Item Details

Item Type:Refereed Article
Keywords:intravenous immunoglobulin, controlled trial, follow up, IVIG, Polyneuropathy, Rituximab, criteria, term
Research Division:Health Sciences
Research Group:Sports science and exercise
Research Field:Motor control
Objective Division:Health
Objective Group:Clinical health
Objective Field:Treatment of human diseases and conditions
UTAS Author:Taylor, BVM (Professor Bruce Taylor)
ID Code:152715
Year Published:2021
Web of Science® Times Cited:1
Deposited By:Medicine
Deposited On:2022-08-23
Last Modified:2022-09-30

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