Dysarthria is a collective term for a group of neurological speech disorders caused by damage to mechanisms of motor control in the central or peripheral nervous system. The dysarthrias vary in nature, depending on the particular neuromotor systems involved. Consequently, a number of issues are considered when devising a management approach for a particular patient. These issues include the type of dysarthria (reflecting the underlying neuromuscular status), the physiological processes involved, severity, and the expected course.

Management of the dysarthrias is generally focused on improving the intelligibility and naturalness of speech, or on helping the speaker convey more communicative intent using speech plus the environment, context, and augmentative aids. Intelligibility refers to the degree to which the listener is able to understand the acoustic signal (Kent et al., 1989). Comprehensibility refers to the dynamic process by which individuals convey communicative intent, using the acoustic signal plus all information available from the environment (Yorkston, Strand, and Kennedy, 1996). In conversational interaction, listeners take advantage of environmental cues such as facial expression, gestures, the situation, the topic, and so on. As the acoustic speech signal becomes more degraded, contextual information becomes more critical for maintaining comprehensibility.

Decisions regarding whether to focus treatment on intelligibility or on comprehensibility depend largely on the severity of the dysarthria. Management for mildly dysarthric individuals focuses on improving intelligibility and naturalness. Individuals with moderate levels of severity benefit from both intelligibility and comprehensibility approaches. Finally, management of very severe dysarthria often focuses on augmentative communication.

Management focus also depends on whether the dysarthria is associated with a condition in which physiological recovery is likely to occur (e.g., cerebrovascular accident) versus one in which the dysarthria is likely to get progressively worse (e.g., amyotrophic lateral sclerosis [ALS]). For patients with degenerative diseases such as ALS, early treatment may focus on maintaining intelligibility. Later in the disease progression, the focus of treatment is less on the acoustic signal and more on communicative interaction, maximizing listener support and environmental cues, allowing the patient to continue to use speech for a much longer period of time before having to use augmentative and alternative communication. Yorkston (1996) provides a comprehensive review of the treatment efficacy literature for the dysarthrias associated with a number of different neurological disorders.