Due to the fact that Amyotrophic Lateral Sclerosis is a progressive disease of the cells of the anterior horn of the medulla, of the motor nuclei of the cranial nerve and of the corticospinal and corticobulbar pathways, and that it damages both upper and lower motor neurons, many patients develop dysarthria, or a difficulty to pronounce words.
The speech of ALS patients is characterized by presenting varying degrees of spasticity, slowness, excessive pauses, and a generalized difficulty pronouncing some phonemes. Their voice tends to be monotonous and with diminished tonal extension. The strength and rhythm of lip movements are reduced, and paralysis or velar paresis can develop. The tongue also becomes hypertrophic and prone to experiencing fasciculations.