Introduction: Multifocal motor neuropathy is a well described condition characterized by slowly progressive, predominantly distal, asymmetric limb weakness and wasting, predominantly in the arms within an anatomical distribution of individual motor nerves, with minimal or no sensory involvement.
Method: The aim of this retrospective study was to look for a significant reduction of the amplitude of sensory potentials in a cohort of 21 patients with defined multifocal motor neuropathy according to the Workshop Report criteria [Workshop Report, 2001. 79th ENMC International Workshop. Multifocal motor neuropathy 14-15 April 2000, Hilversum. The Netherlands. Muscle Nerve 11, 309-314], within a follow-up of at least 3 years.
Result: Thirteen patients (62%) (Group 1) had a reduction of the amplitude of at least one sensory potential, of whom four patients had abnormalities of two or more sensory potentials, while eight patients (Group 2) had no abnormality. No significant differences were found for gender, age at onset, number of involved motor nerves, CSF protein count, presence/absence of anti-GM1 serum antibodies and response to IgIV between the two groups.
Conclusion: This study underlines the difficulty in defining criteria for multifocal motor neuropathies capable of distinguishing them from other chronic acquired demyelinating polyneuropathies, and mainly from multifocal acquired demyelinating sensory and motor (MADSAM) neuropathy, also called Lewis-Sumner's syndrome.