Multifocal Motor Neuropathy: A Single Center Experience (P3.146)

Objective: To characterize a single center cohort of patients with multifocal motor neuropathy (MMN) with extended follow-up. Background: MMN is an immune-mediated demyelinating neuropathy with prevalence of 1-2/100,000. A consistent feature is high intravenous immunoglobulin (IVIG) requirement, and latter development of treatment refractoriness. Other immunomodulatory therapies have not shown consistent benefit, but reports of off-label rituximab use have suggested promise. Our experience is stabilization of disease progression may occur with concurrent rituximab therapy. Methods: A single-center cohort study was conducted involving the state quaternary neuropathy service in Western Australia, a population of just over 2.5 million. Patients with MMN, all of who received IVIG therapy during follow-up, were enrolled. All patients had clinical assessment by one neurologist. Results: 19 patients (12 males, 8 females) were identified. Age at symptom onset ranged from 17 to 60 years. The duration of follow up ranged from 23 to 155 months (mean 94 months). Every individual had upper limb involvement at diagnosis with 3/19 developing lower limb involvement. Sensory symptoms were reported in 8/19. Anti-ganglioside antibodies were positive in 3/19 cases. IVIG greater than 1g/kg/month was required to maintain clinical stability in most treated patients. Rituximab was used in 4 cases with disease progression despite IVIG 2g/kg/month, with improved disease control, but no reduction in IVIG requirements. A single patient with clinical response to concurrent quinidine therapy was observed. Conclusions: Our large cohort with extended follow-up demonstrates the spectrum of MMN phenotype and treatment response. Despite the slowly progressive nature of this disease, almost all treated individuals maintain functional status. IVIG monotherapy is effective in the majority of cases. There appears to be a role for rituximab in restoring IVIG responsiveness in refractory disease. Disclosure: Dr. Saw has nothing to disclose. Dr. O9Connor has nothing to disclose. Dr. John has nothing to disclose. Dr. Nolan has nothing to disclose. Dr. Leong has nothing to disclose.