What are Motor Speech Disorders?
Motor speech disorders are clinical conditions resulting from impairments in the nervous system processes involved in speech production, which can reduce speech intelligibility. The primary issue in these disorders is the control of speech muscles and/or the planning of speech movements.
For speech to be intelligible, five basic components must work in harmony:
- Respiration (Breath support)
- Phonation (Voice production)
- Articulation (Speech sound production)
- Resonance
- Prosody (Stress, rhythm, and intonation)
An impairment in any of these components can manifest with different symptoms in speech.
Types of Motor Speech Disorders
1. What is Dysarthria?
Dysarthria is a motor speech disorder caused by involvement of the central and/or peripheral nervous system, resulting in weakness, poor coordination, changes in muscle tone, or involuntary movements of the speech muscles. It can significantly decrease speech intelligibility.
Conditions that can lead to dysarthria:
- In childhood: Cerebral palsy and developmental neurological conditions.
- Acquired: Stroke, traumatic brain injury, tumors.
- Progressive: Parkinsonism, MS, ALS, Myasthenia Gravis, etc.
Common symptoms of dysarthria:
- Slurred or distorted speech
- Muffled, breathy, or strained voice quality
- Reduced vocal loudness or hypernasality (nasal-sounding speech)
- Monotone speech, or speech rate that is very slow or irregular
2. What is Apraxia of Speech?
Apraxia of speech occurs due to difficulties in planning and programming the movements necessary for speech, even when there is no significant muscle weakness. The individual knows what they want to say, but the brain struggles to initiate the movements in the correct sequence.
Childhood Apraxia of Speech (CAS)
Occurs during the developmental process. Signs that may raise suspicion include:
- Inconsistency (saying the same word differently each time)
- "Groping" behavior (silent searching movements of the mouth) when trying to find a sound/syllable
- Significant difficulty with long words and lengthened syllable transitions
- Abnormal stress and intonation (prosody errors)
Acquired Apraxia of Speech
Appears after brain damage (stroke, trauma, etc.). It is typically characterized by sound additions, deletions, difficulty initiating words, and frequent hesitations.
Evaluation and Therapy Process
An evaluation by a Speech and Language Therapist may include the following steps:
- Oral-motor examination: Checking muscle tone, strength, and coordination.
- Speech analysis: Assessment of intelligibility, rate, and articulation.
- Swallowing screening: Checking for drooling or signs of swallowing difficulty (dysphagia).
- Instrumental analysis: Acoustic analysis or endoscopic examinations if necessary.
Therapy Goals
Therapy is individualized based on evaluation results. The primary goal is functional communication:
- For Dysarthria: Increasing respiratory support, strengthening voice production, and clarifying articulation.
- For Apraxia: Improving voluntary control of speech movements, gradual construction of syllable/word structures, and consistency.
Augmentative and Alternative Communication (AAC): In cases where speech is severely limited, personalized AAC strategies (cards, apps, or devices) can be planned to maintain communication.
When Should You Seek Help?
- If speech is significantly difficult to understand
- If the voice is very low, muffled, or monotone
- If errors are inconsistent (same word produced differently)
- If swallowing difficulties or drooling accompany speech issues
- If speech has changed following a neurological event
Significant progress in communication skills can be achieved through early evaluation and regular therapy.
You can schedule an appointment with the Istanbul Atlas University Speech and Language Therapy Unit.