# Long‐Term Functional Outcomes in Immunoglobulin‐Treated Multifocal Motor Neuropathy Evaluated Through the MMN‐Rasch‐Built Overall Disability Scale

## TL;DR

Most patients with multifocal motor neuropathy show long-term functional improvement with immunoglobulin treatment, though dosing varies significantly between centers.

## Contribution

This study provides long-term evidence of functional improvement in MMN patients using the MMN-RODS scale and highlights inter-center dosing variability.

## Key findings

- 90.6% of MMN patients showed improved disability scores over a mean of 6.2 years.
- Birmingham patients received higher immunoglobulin doses compared to Southampton patients.
- Dose dependency was more common after dose increases than decreases.

## Abstract

Long‐term functional outcomes are uncertain in immunoglobulin‐treated multifocal motor neuropathy (MMN).

We retrospectively studied consecutive subjects with MMN from two neuromuscular centres in Southampton and Birmingham, UK. Initial and latest MMN‐Rasch‐built Overall Disability Scale (MMN‐RODS) scores and latest immunoglobulin doses were collected. Latest dose alterations and resulting MMN‐RODS changes were ascertained.

We included 32 subjects with MMN (14 females and 18 males). Mean age was 60.0 years (SD: 11.7). Over a mean of 6.2 years, MMN‐RODS scores improved in 29 out of 32 (90.6%) subjects and worsened in 3 out of 32 (9.4%) subjects. Mean latest centile MMN‐RODS was improved compared to mean initial centile MMN‐RODS (81.53 [SD: 14.14] vs. 63.47 [SD: 13.82]; p < 0.001). Mean latest immunoglobulin dose was 26.3 g/week (range: 4–70). There were no associations of the latest immunoglobulin dose with age/disease duration/weight/gender/comorbidities/initial disability/latest disability. There were no inter‐centre differences in age/disease duration/weight/gender/comorbidities/initial disability/latest disability. The latest mean immunoglobulin dose was higher in Birmingham than in Southampton (33.9 g/week [SD: 17.1] vs. 18.8 g/week [SD: 8.0]; p = 0.004). Immunoglobulin dose dependency was observed in 16 out of 17 subjects whose last dose alteration was incremental, and in only 3 out of 15 subjects whose last dose alteration was decremental. Dose dependency was demonstrated in a greater proportion of subjects from Birmingham compared to Southampton (13/16 vs. 6/16; p = 0.03).

Function as ascertained by the MMN‐RODS shows sustained improvement over > 6 years with individualised immunoglobulin dosing in most subjects with MMN. The large inter‐centre/inter‐individual dosing and dose dependency variations observed may suggest implications of patient‐ and physician‐related factors, which require further study.