Which statement describes an important diagnostic distinction between apraxia of speech and dysarthria?

• A. Apraxia of speech is a result of lower motor neuron lesions, whereas dysarthria is the result of upper motor neuron lesions.
• B. Clients with apraxia lack the ability to monitor reactive speech, whereas clients with dysarthria lack the ability to sequence volitional speech movements.
• C. Strength and coordination of the speech musculature are intact in clients with apraxia of speech, whereas slowness, weakness, incoordination, or altered tone of the speech musculature are associated with dysarthria.
• D. Apraxia of speech is characterized by distortions, omissions, and substitutions, whereas dysarthria is characterized by inconsistent, highly variable misarticulations.

Answer: (C)

The main idea here is distinguishing planning for speech from execution of speech movements. In apraxia of speech, the problem lies in planning and sequencing the movements needed to produce speech, while the muscles themselves are able to function. That’s why strength and coordination of the speech musculature are typically intact. You’ll often notice groping, trials and errors, and inconsistent articulation, especially on longer or more complex words, despite preserved strength.

In dysarthria, the issue is with execution. The neuromuscular system that carries out the speech movements is impaired, leading to slowness, weakness, poor coordination, or altered tone in the speech muscles. This tends to produce more consistent, predictable articulation errors and noticeable changes in rate, voice quality, and resonance, depending on the dysarthria type.

Therefore, the statement that strength and coordination are intact in apraxia of speech, whereas weakness, slowness, incoordination, or altered tone are associated with dysarthria, best captures the diagnostic distinction.