Q: Would you agree with the following statement: Children with apraxia will respond to structured production of increasingly difficult syllable shapes, while children with dysarthria need supplementing with oral motor exercises to address muscle weakness.
Before I answer your question, let me say a few things about “muscle weakness” and dysarthria because many SLPs––including professors of articulation and phonology––do not seem to understand this area very well. The muscle weakness seen in dysarthria can have many different causes, and the treatment will be no good unless the cause is taken into consideration. One cannot simply do “oral motor exercises” to address “muscle weakness.” It is much more involved than that.
It all boils down to the differential diagnosis of the muscle tone disturbance. For example, muscle weakness can be caused by muscle tightness (spasticity). Increasing muscle “strength” will not help the client move better in that case. In fact it may only make his spasticity worse. The therapy needs to include activities to reduce the spasticity while improving overall tone. The therapy will be more about increasing flexibility and range in the tight areas, and learning to move with the right points of mobility and stability. The therapy will be more about inhibiting unhelpful movements while facilitating appropriate movements. It will be much less about building “strength” per se.
Let’s carry this example into speech: A client with dysarthria may have limited tongue movements, and his tongue may seem “weak.” But very tight muscles in the shoulders, neck, and jaw could be causing the limited tongue movements. Activities to improve strength in the tongue probably will have a limited effect on speech movement because that is not the problem. The problem is that proximal tension (shoulders, neck, jaw) is inhibiting distal mobility (tongue). The therapy needs to include activities to relax or inhibit the tension, and it needs to include activities to increase tongue mobility. The therapy is one of improving the oral movement patterns, not of increasing strength. The tongue’s actual “strength” has very little to do with it.
[By the way, a number of techniques to inhibit muscular tension related to dysarthria were demonstrated in The King’s Speech. The therapist included rolling, rocking, shaking, and other techniques to release tension in the diaphragm, chest, neck, and jaw.]
The Differences Between Apraxia and Dysarthria
This is what has helped me to understand the difference between apraxia and dysarthria: Ultimately apraxia is a problem in the perception of movement, while dysarthria is a problem in the execution of movement. A client who does not perceive his own movements well (apraxia) will not know how to plan out subsequent movements. He will lack the initiative to move and/or will move inconsistently and thus perform poorly. A client who cannot execute his movements well (dysarthria) also will perform poorly. The impact on speech can be very similar, especially in children, and both types of clients may need to work on many of the same skills. The focus will be different. The focus in apraxia will be on perception whereas the focus in dysarthria will be on execution.
The Similarities Between Apraxia and Dysarthria
In many ways therapy for children with apraxia and dysarthria looks exactly the same:
- Both need to improve tactile and proprioceptive awareness of their oral structures, and the movements of those structures.
- Both need to improve dissociation, direction, and grading of their own controlled speech movements.
- Both need help in maturing their speech movements along several continuums: gross-to-fine, proximal-to-distal, medial-to-lateral-to-rotational, and so forth.
- Both need to learn how to move the oral mechanism in specific ways for specific phonemes (consonants and vowels).
- Both need to learn how to sequence vowels into diphthongs.
- Both need to learn how to sequence phonemes into syllables.
- Both need to learn how to sequence syllables into words, and maintaining syllables in words.
- Both often need work on breath support for speech so their words, phrases, and sentences can be stronger and longer, and so prosody improves.
- Both often need work on producing voice, and differentiating between voiced and voice-less phonemes.
- Both often need work on resonance, and to learn to recognize when they are producing voiced and voiceless phonemes.
- Both often need help organizing phonemes by place of articulation.
- Both almost always need auditory training and phonological awareness activities to assist in their speech movement learning.
The Final Analysis
I think it is safe to say that once a wide variety of phonemes are emerging–
- Kids with apraxia need more work on phonemes and syllable sequencing
- Kids with dysarthria need more work elocution, enunciation, and precision of sound production.
What I Wish
I wish we could drop both of these terms, and simply call these children speech movement impaired. That way we could perhaps stop obsessing about “apraxia” and “dysarthria,” and we could begin to discuss the real underlying sensory-motor issues. We could begin to talk openly and honestly about the diagnosis and treatment of speech movement problems. For example:
- What does it mean to have a muscle tone disturbance, and how does high or low tone effect speech movement learning? How does spasticity interfere with speech movement learning? How does it interfere with jaw, lip, tongue, or velar movement? How does it interfere with respiration, phonation, and resonation? How does one influence muscle tone?
- What is a vestibular deficit? How does vestibular stimulation affect muscle tone and arousal for learning speech movements?
- What does it mean that a client has tactile defensiveness, oral-tactile hyper- or hyposensitivity? How do these problems interfere with speech movement learning? How do tactile awareness and discrimination activities improve speech movement learning?
- What does it mean if a client has retention of primitive reflexes? How does this interfere with speech movement learning? What should we do about them? How can reflexes be used to stimulate speech movement learning?
- How does one teach dissociation of speech movement? Why does one do this? What does the term “grading” of oral movement mean? How can we teach it?
- What is the process of inhibition and facilitation of movement? How can we use it to facilitate better jaw, lip, or tongue movement for speech sound production?
The Problem We Have Today
As I see it, the problem we have today is that the “anti oral-motor people” have moved the discussion away from real sensory-motor issues and into the arenas of “motor learning theory” and “non-speech oral motor exercises.” Put simply, they have knocked the discussion off track. They are complaining about horns, whistles, strength, and the number of repetitions of certain movements that may be necessary to improve speech, but these are not the issues. The issues listed above (and many more) are the real oral motor issues that therapists have been discussing for more than 30 years.
For example, therapists who use and teach “oral-motor techniques” have not been talking about whether blowing a whistle ten times per day for ten weeks will cause /w/, /p/, or /b/ to emerge. Real therapists who do real work have been discussing how one can use tactile, proprioceptive, and vestibular stimulation to influence lip movement. A whistle might be used in the process…or a horn…or a straw…or a gummy worm…or a toothette handle…or a swizzle stick…but whether or not the client can blow the whistle is immaterial.
The real questions are quite basic:
- What movement is needed?
- What is interfering with emergence of the movement?
- How might the movement be facilitated?
- How might the movement be brought to the client’s awareness?
- How might we help the client use the movement to make a speech sound?
- How might we help the client use the movement in speech with better speed and accuracy?
- How might we help the client use the movement in speech consistently under a variety of circumstances?
- How might we help him remember to use the movement in speech when we are not around?
If we could stop arguing about what apraxia and dysarthria are, and if we could stop talking about “non-speech oral-motor exercises,” we could elevate the discussion to one that actually would help therapists understand what the therapy is all about when a client has a motor speech disorder.