Dysarthria

Apart from a few exceptions (e.g., ingressive clicks of the !Kung San people), the speech sounds produced by a speaker of any human language system arise from a modulation of the expiratory air flow at the level of the vocal folds (glottis) and various supralaryngeal structures, especially, the velum, tongue, and lips. Thus, verbal utterances are built upon coordinated—and largely automatized—sequences of respiratory, laryngeal, and orofacial movement patterns. As a rule, the term dysarthria is applied to abnormalities of spoken language due to impaired control of these sound generation mechanisms following dysfunctions of the central or peripheral nervous system, including (neuro)muscular diseases such as myasthenia gravis or polymyositis. Dysarthric deficits, therefore, reflect a disruption of the elementary motor processes bound to speech production such as ...