Hypokinetic Dysarthria is a motor speech disorder that is often associated with Parkinson’s disease (PD). It can occur when there is interference in the basal ganglia control circuit. These disruptions can include “degenerative, vascular, traumatic, infectious, inflammatory, neoplastic, and toxic-metabolic diseases (Duffy, 2013, p. 176).” Damage to the basal ganglia control circuit results in reduced range of motion as well as the inability to inhibit involuntary movements. Hypokinetic dysarthria is most commonly caused by PD; a progressive, neurogenic disease that is characterized by tremor, rigidity, slowness of movement, and incoordination. Eighty-seven percent of hypokinetic dysarthria cases are associated with degenerative disease (Duffy, 2013).
Nonspeech signs associated with hypokinetic dysarthria may include characteristics dealing with the face, eyes, hands, arms, and trunk. The individual may have an expressionless look to their face as well as weakness with gestures in the hands, arms, and face that would normally match the person’s prosody when speaking. Overall, their social interaction with others can be emotionless. Eye blinking occurs less frequently than normal and their head gaze does not match where their eyes are looking. These patients swallow infrequently which leads to drooling. A tremor may be present in the jaw, lips, and tongue as well as limited movement during speech even though strength of these structures is often normal.
The most common speech symptom is hypophonia which is reduced vocal loudness. Hypokinetic dysarthria often is associated with variables of pitch and loudness where a patient may be monopitch or exhibit monoloudness (Johnson & Adams, 2006). Speech movements have limited range of motion because of rigidity in the muscle tone which adds resistance to movement in all directions. Individual movements are reduced but repetitive movements can be fast. Speech rate can be variable where short phrases, rushes of speech, reduced stress, and imprecise consonants may occur.
One researched treatment procedure for hypokinetic dysarthria is the use of delayed auditory feedback (DAF). Delayed auditory feedback is a device that captures a person’s speech and delays the auditory feedback varying from 20 msec to a maximum of 200 msec. When the individual hears the delay of the auditory feedback, it requires the person to “catch up” to their speech. The person will slow their rate by vowel prolongation, producing syllables at the same rate, and providing smooth transitions between words and phrases. This instrument can be a personal device that the individual can wear or it can be a computer program.
In a study done by Hanson and Metter (1980), a 59-year-old male with progressive supranuclear palsy, a progressive neurologic disorder, used DAF to increase speech intelligibility. The purpose of this treatment was to measure speaking rate, vocal intensity, and overall speech intelligibility...