CHAPTER 11
Chapter Overview
Apraxia of speech (AOS) is a disorder of motor sequencing. In some definitions, it is
noted to be a phonetic-motoric disorder. It is not caused by muscle weakness, abnormal
muscle tone, reduced range of movement, or decreased muscle steadiness. Pure
apraxia of speech (without a co-occurring aphasia or dysarthria) is rare. Although it had
been held that speech errors were variable from trial to trial, recent research shows that
speech errors in AOS are relatively consistent for both type and location during repeated
productions of the same word or phrase. There are several types of apraxia, including
ideational apraxia and ideomotor apraxia. Ideational apraxia is a disturbance in the idea
or purpose of a movement, while ideomotor apraxia is a disturbance in the performance
needed to complete an action. Apraxia of speech is a subcategory of ideomotor apraxia.
The neurologic “mechanism” thought to control the process of sequencing motor
commands is the motor speech programmer, a neural network in the brain that
sequences the motor movements needed to produce speech accurately. Research
indicated that it is located near the perisylvian area of the left hemisphere, where there is
close association with the language and motor centers of the brain. Disorders that
damage the motor speech programmer have the potential to cause apraxia of speech.
These include stroke, degenerative disease, trauma, and tumor, with the most common
cause being stroke. Apraxia of speech is primarily a disorder of articulation and prosody,
with speech being slow, labored, and halting, with some instances of articulatory groping.
Individuals at the most severe and mild ends of the disorder typically demonstrate fewer
examples of characteristic errors than persons in the moderate range of severity.
Articulation errors arise from deficits in the patient’s ability to smoothly sequence oral
Motor Speech Disorders, Second Edition
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Treatment of apraxia of speech generally involves behaviorally based procedures that
help affected individuals improve their ability to select and sequence speech sounds
correctly. Most well-known treatments involve one-on-one intensive therapy. Keeping in
mind the goal of treating apraxia of speech is to help the patient relearn the motor
sequences needed to produce phonemes accurately, guiding principles include: not all
individuals are appropriate candidates for treatment; patients and families need to
understand characteristics of apraxia and the rationale for treatment; repetitive and
Study Questions and Answers
1. Define apraxia of speech in your own words.
2. Describe how apraxia of speech is both similar to and different from dysarthria.
3. How are ideational apraxia and ideomotor apraxia different?
4. Limb apraxia, nonverbal oral apraxia, and apraxia of speech are subcategories
of which type of apraxia?
5. What is the difference between nonverbal oral apraxia and apraxia of speech?
6. What is the motor speech programmer?
7. The motor speech programmer receives input from what other parts of the
brain?
8. What is the most common cause of apraxia of speech?
9. Why do patients with mild or severe apraxia of speech typically demonstrate
fewer apraxic errors than patients with moderate apraxia of speech?
10. Apraxia of speech is primarily a disorder of which two components of speech
production?
11. What are two of the possible ways in which apraxia of speech affects prosody?
12. When making the diagnosis of apraxia of speech, why must such conditions as
weakness and reduced range of movement be eliminated as possible causes of
a speech disorder?
13. Why can it be especially difficult to distinguish apraxia of speech from Broca’s
aphasia?
14. What is one of the most sensitive evaluation tasks for identifying apraxia of
speech?
15. What is integral stimulation? Which apraxia treatments have incorporated it
into their treatment procedure?