Multifocal motor neuropathy in Austria: a nationwide survey of clinical features and response to treatment

Abstract

Background and objectivesMultifocal motor neuropathy (MMN) is a rare neuropathy and detailed descriptions of larger patient cohorts are scarce. The objective of this study was to evaluate epidemiological, clinical, and laboratory features of MMN patients and their response to treatment in Austria and to compare these data with those from the literature.MethodsAnonymized demographic and clinical data about MMN patients until 31.12.2017 were collected from registered Austrian neurologists. Exploratory statistics on clinical and laboratory features as well as treatment regimens and responses were performed.Results57 Patients with MMN were identified, resulting in a prevalence of 0.65/100.000. Mean age of onset was 44.1 ± 13.1 years, the diagnostic delay 5.5 ± 8.4 years. In 77% of patients, symptom onset was in the upper limbs, and in 92%, it occurred in distal muscles. Proximal onset was never observed in the lower limbs. At the final follow-up, the majority of patients had atrophy (88%) in affected regions. Definite motor conduction blocks (CB) were found in 54 patients. Anti-GM1-IgM antibodies were present in 43%. Treatment with intravenous immunoglobulins improved muscle strength and INCAT score initially, but at last follow-up, both scores deteriorated to values before treatment.DiscussionThe findings of the present study corroborate the previous findings in MMN. Onset typically occurs in the upper limbs and mostly distal, CBs are found in the majority of cases, while anti-GM1-IgM antibodies are detected in only approximately 40%. Our study underlines that the initial good response to treatment fades over time.

Incidence and mortality rates of Guillain‐Barré syndrome in Serbia

“…1,10,14,[23][24][25] Auto-immune neuropathies, such as multifocal motor neuropathy and chronic inflammatory demyelinating polyneuropathy, are also more common in males. 26,27 However, some studies of GBS in children and adolescents showed female predominance. 20,28 Many other auto-immune diseases are more common in the female population.…”

A Case of Probable Multifocal Motor Neuropathy With Clinical Stability for Ten Years After a Single Treatment of Rituximab

“…8,9 The utility of IVIG in MMN is supported by randomized controlled trials, 10 and subcutaneous immunoglobulin has shown similar efficacy. 11 However, the response may be partial and often diminishes over time, 1,2 with decline in strength typically beginning after 3-8 years of IVIG treatment. 2,4 It is suspected that the relatively low response to IVIG compared with the more robust improvement seen in chronic inflammatory demyelinating polyradiculoneuropathy may be related to the differences in disease pathophysiology.…”

“…11 However, the response may be partial and often diminishes over time, 1,2 with decline in strength typically beginning after 3-8 years of IVIG treatment. 2,4 It is suspected that the relatively low response to IVIG compared with the more robust improvement seen in chronic inflammatory demyelinating polyradiculoneuropathy may be related to the differences in disease pathophysiology. 12 Although IVIG is established as first-line therapy, there is no widely accepted secondline agent for the treatment of MMN.…”

“…The prevalence of MMN is approximately 0.6 per 100,000 people, with a male predominance, and it typically begins in the fourth-fifth decades of life. 1,2 MMN is characterized by asymmetric, predominantly distal, slowly progressive weakness in the distribution of 2 or more individual peripheral nerves without significant sensory abnormalities. Often, upper limb involvement predominates, and cramps and fasciculations may be present.…”

Can MR Neurography Differentiate between Amyotrophic Lateral Sclerosis and Multifocal Motor Neuropathy?

“…Early differentiation is of utmost importance, however, as MMN is thought to be an autoimmune-mediated disorder (ie, can be treated fairly well), whereas there is no known cure for ALS. Patients with MMN receiving intravenous immunoglobulin or immunosuppressive therapy may respond quickly to therapy, with only mild symptoms remaining over a longer period (7). However, it must be noted that MMN will remain a slowly progressing disease.…”