Q: My client has low tone and many deviant phonological processes. Is this common? Does this mean he has dysarthria? How should my treatment look different from traditional articulation or phonological therapy?
Yes! If the child has hypotonia then this is dysarthria. Whenever you have muscle tone problems of a global nature, then dysarthria is the diagnosis. Dysarthria is a speech movement problem that is the result of muscle tone disturbance. (See definitions below)
It is common for children with low muscle tone to have speech movement problems, but the specific phonetic and phonological errors will be specific to the child.
In general all kids with severe speech disorders have the same basic problems to various degrees–– final consonant deletion, initial consonant deletion, cluster reduction, cluster deletion, prevocalic voicing, fronting and/or backing, stopping, stridency deletion, syllable deletion, etc. Dysarthric kids usually have vowel distortion, and both apraxic and dysarthric kids usually have an incomplete vowel set. Diphthongs often are shorted into single vowels and the schwa is over-used in both groups. Distortion of phonemes and the supersegmentals is the hallmark of dysarthria.
A client with a motor speech disorder needs to be viewed from all four speech movement subsystems–– Respiration, phonation, resonation, and articulation (jaw, lip, and tongue movement). His are not simple phoneme errors. His phoneme errors are the result of problems in the four movement subsystems.
In terms of therapy, the short and simple answer is that you work on phonemes and phonological processes just like you would for any other client, but you add work specifically to get the child to understand how his body works to inhale, exhale, prolong exhalation, turn his voice on and off, make sound oral and nasal, and move his jaw lips, and tongue in better patterns of mobility and stability. That is why therapists use blow toys, mirrors, tubes, and so forth. In the case of dysarthria, exaggeration is a key piece of treatment. Over-pronunciation is a key to clarity.
Classic Definitions of Dysarthria
“Dysarthria comprises a group of speech disorders resulting from disturbances in muscular control. Because there has been damage to the central or peripheral nervous system resulting in some degree of weakness, slowness, incoordination, or altered muscle tone.”
From: Darley, F. L., & Aronson, A. E., & Brown, J. R. (1975) Motor Speech Disorders. Philadelphia: W. B. Saunders.
“A generic label for a group of motor speech disorders caused by weakness, paralysis, slowness, incoordination, or sensory loss in the muscle groups responsible for speech”
From: Brookshire, R. H. (1992). Introduction to Neurogenic Communication Disorders. St. Louis: Mosby.