We report the case of a 66-year-old female who presented with dysarthria and dysphonia. Brain MRI abnormalities showed confluent white matter lesions and subcortical lacunar infarcts, suggesting cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL), confirmed by the presence of a heterozygous mutation in the Notch3 gene. Clinical signs and course were consistent with amyotrophic lateral sclerosis (ALS) as was the electromyographic pattern. The possible pathogenic role for a mutation in the Notch3 gene is discussed considering recent data on hypoxia in the pathophysiology of ALS.