114 Chapter 6
Apraxia of speech therapy assumes that the patient has lost memory for planning, sequencing,
and executing motor speech acts. Repeatedly performing these acts helps the patient to recall and
relearn them. The motor acts should begin with simple speech acts and gradually increase to more
complex ones. Repetition is also fundamental in treating apraxia of speech using melodic intona-
tion therapy (Sparks, Helm, & Albert, 1974). In this therapy, a rhythm or melody is applied to an
utterance, causing it to be programmed, sequenced, and executed more easily; then the melody
is gradually reduced and eventually eliminated. (This is another similarity between apraxia of
speech and stuttering.) Other therapies for apraxia of speech include the initial use of whisper-
ing, sentence completion exercises, shifting from automatic to purposeful utterances, and using
nonverbal gestures to facilitate purposeful utterances. Conventional therapies for patients with
nonf luent aphasia can also be applied to apraxia of speech. No therapies for apraxia of speech have
been shown to help all patients, and careful ongoing assessment is needed to decide if a par tic u lar
patient is benefiting from treatment.
Dysarthria and the Motor Speech Processes
In severe apraxia of speech, the patient may be unable to program respiration, phonation, and
articulation for purposeful speech. Apraxia of speech is usually limited to prob lems with program-
ming the articulators; the other aspects of motor speech are unimpaired or minimally disrupted.
However, the dysarthrias generally disrupt one or more of the five basic motor speech pro cesses:
respiration, phonation, articulation, resonance, and prosody (Darley et al., 1975). Respiration pro-
vides the support for speech production. Phonation and resonance are the sound source and reso-
nating system, respectively, of the speech production mechanism. Articulation involves shaping
the oral tract to create recognizable speech sounds, and prosody is the stress, intonation, rhythm,
and fluency of speech that extend across one or more segments of an utterance.
Dysarthria and Respiratory Support
Respiration, as noted earlier, serves as a driving force for speech production. Compressed air
from the lungs displaces anatomical structures, and the air is forced through constrictions to
produce speech sounds. The respiratory system works similarly to a bellow; the size of the thorax
is changed to vary the pressure in the lungs. Inhalation is the rush of air from regions of high
pressure to regions of low pressure; exhalation is the opposite. Respiration operates on Boyle’s law
and the kinetic theory of gases (Zemlin, 1998), describing air movement from regions of differing
pressure.
Severe generalized dysarthrias affect the respiratory system, disrupting the driving force for
speech. Mixed and multiple dysarthrias, such as those occurring in amyotrophic lateral sclero-
sis (ALS), multiple sclerosis, and other progressive neurological diseases, ultimately impair the
muscles of respiration so that patients can no longer expand and contract the thorax adequately
for speech. When respiratory support for speech production is impaired, patients tend to speak at a
slow rate, with short phrasing, and with prolonged intervals between syllables, words, and phrases.
In addition, during normal speech, the respiratory system adjusts for impedance variations in the
oral tract. With greater impedance to airf low, such as occurs with obstruent consonants, the respi-
ratory system must adjust for the increased re sis tance by reducing the force of muscular contrac-
tions. Without this adjustment, speech is produced with excess and inappropriate stress.
In some patients with severely compromised respiration, velopharyngeal incompetence exacer-
bates the lack of respiratory support. Because the patient cannot effectively seal off the nasal cavity,
air leaks from the oral cavity. In feeble and weak patients, this air leakage reduces the pressure
behind articulatory valves, decreasing intelligibility.
Patients with severely compromised respiration often have tracheotomies and are maintained
on respirators or ventilators. Speech is pos si ble with some types of tracheotomies, and some