2025 American Academy of Neurology Abstract Website

Objective:

Determining the chronic effects of intravenous immunoglobulin (IVIg) therapy and the most sensitive outcome measures in patients with MMN

Background:

Multifocal motor neuropathy (MMN) is a rare form of acquired autoimmune neuropathy. Progressive deterioration of patients' abilities and quality of life characterizes the natural course of the disease. Intravenous immunoglobulin therapy (IVIg) has been shown to be effective in alleviating motor symptoms and slowing the progression of MMN.

Design/Methods:

Study included 10 patients with MMN on chronic IVIg therapy. The following methods were used to assess the response to therapy: manual muscle strength testing assessed by the Medical Research Council (MRC) scale with a summary score including MRC-SS-10 and MRC-SS -20, hand grip strength, as well as the MMN-RODS disability scale

Results:

Statistically significant improvement of the condition was observed on day 7 of IVIg administration compared to the finding at the initial point. 7 days after IVIg administration, MRC-SS-20 was the most sensitive to detect the change with a sensitivity of about 70%. At the 6-month time point, the MRC-SS-10 and MRC-SS-20 with a clinically significant change of 2 points were the most sensitive to detect worsening. Improvement was best detected by MRC- SS-20 and by right hand grip strength with a significant change of 8kPa. At the 12-month time point, the MMN-RODS scale detected deterioration in as many as 40% of patients. The MRC-SS-20 was the most sensitive measure for detecting clinical improvement.

Conclusions:

There are significant fluctuations in the condition of patients with MMN on chronic IVIg therapy. Very high sensitivity of MRC-SS, especially MRC-SS-20 for detecting clinically significant changes, was shown. Adjustment of dose and frequency of administration of IVIg therapy should be catered to the individual needs of each patient with MMN.