The term amyotrophic lateral sclerosis was first introduced by Charcot to describe cases with mixed upper and lower motor neuron signs without sensory impairment. Later the syndromes of progressive bulbar palsy (PBP) and progressive muscular atrophy (PMA) were recognized to be variations of the same pathological process, and ALS was used as an inclusive term to refer to these syndromes as well. Although some authors reserve the term ALS for the specific syndrome of mixed upper and lower motor neuron lesions and use the term “motor neuron disease” to refer to the constellation of syndromes, most of the literature on familial cases uses ALS as a generic title. We will adhere to this convention
