Rapidly progressive amyotrophic lateral sclerosis initially masquerading as a demyelinating neuropathy

Abstract

Rare cases of demyelinating neuropathy have been described in association with amyotrophic lateral sclerosis (ALS). We report two patients with typical ALS whose initial electroneuromyographic (ENMG) presentation could suggest the existence of a process of motor nerve fiber demyelination. However, subsequent ENMG examinations and the fatal course of the disease in a few months rather supported severe ongoing axonal degeneration at the origin of motor nerve conduction abnormalities. Repeated examinations could be required to distinguish between ENMG features of concomitant demyelinating neuropathy and rapidly progressive motor neuron loss in ALS.

Keywords: ALS; Amyotrophic lateral sclerosis; CIDP; CMAP; Chronic inflammatory demyelinating polyneuropathy; Compound muscle action potential; Conduction block; Demyelination; Disease progression; Dégénérescence; Démyélinisation; EMG; ENMG; Electroneuromyographic examination; MMN; MRC; MRI; Magnetic resonance imaging; Medical Research Council; Motor neuron disorder; Multifocal motor neuropathy; Needle electromyography; Neuropathie; Neuropathy; Progression de la maladie; Wallerian degeneration.