Clinical and electrophysiological aspects in amyotrophic lateral sclerosis syndromes associated to gammopathies

Abstract

The sensory or sensitivo-motor neuropathies were the most described Peripheral neurological complications of benign or malignant monoclonal gammopathy (MG). Cases of pure motor impairment simulating amyotrophic lateral sclerosis (ALS) have more rarely been described. Herein we describe the clinical and electrophysiological aspects of three patients presenting an ALS like clinical syndrome associated to a MG and we stand out the particular features. There were two men and one woman with an average age of 61.3 years. All patients had a progressive weakness of 4 members and two of them presented a deglutition disorder. All patients became bedridden after few months of the onset. All patients had a very evocative clinical signs of ALS without subjective neither objective sensory troubles. An ALS clinical syndrome in its polyneuritic form was encountered in one patient. In all cases, the electromyographic data were compatible with an attack of the neurons of the anterior horn: many potentials of fibrillation, potential of fasciculation at rest and reducing of the number of potential motor unit during the voluntary contraction with increase in their amplitude and duration. Low amplitudes in motor nerve compound muscle action potentials were noted at the level of at least one nervous trunk in all patients. Low amplitudes of sensory nerve action potential were shown in one patient. MG type was demonstrated during the hospitalization in all patients. Two patients had non Ig M MG of undetermined significance and one patient had Ig M MG associated to a myeloma. Sensory potentials impairment in ALS syndrome has to prompt us to search for an underlying aetiology and especially for GM.