Dysarthria is a speech disorder that is caused by the degeneration of a muscle or certain brain structures.
These affected structures are the medulla oblongata or the cortex in the latter case.
Multiple sclerosis (a neurological disease) or a stroke can cause dysrathrias.
Parkinson’s disease and Huntington’s disease are some of the neurological diseases that lead to dysarthria. Only the expression is altered.
It is not caused by damage to the organs of phonation (tongue, lips, palate) and must be differentiated from aphasia, which is an oral and/or written language disorder affecting the expression and understanding of speech. language (aphasia is found in particular in Alzheimer’s disease).
Patients have weakness, slowness, or incoordination in breathing, articulation, phonation, rate, and/or prosody (loudness and duration of sound).
The condition is often characterized by slurred or slow speech that can be difficult to understand.
The different forms of dysarthria
Here is the classification of dysarthria with the pathologies in parentheses.
1. Spastic dysarthria (stroke).
2. Flaccid dysarthria (neuropathy innervating the effector muscles of the face, for example).
3. Ataxic dysarthria (involvement of the cerebellum).
4. Hypokinetic (Parkinson’s disease) and hyperkinetic dysarthria (Huntington’s disease).
5. Mixed dysarthria (head trauma, multiple sclerosis, amyotrophic lateral sclerosis).
How are dysarthria assessed?
GRBAS stands for Grade, Breathness, Roughness, Asthenicity and Strain.
G (for Grade): what is the general impression of the quality of the voice?
R (for Roughness): is the voice hoarse?.
B (for Breathness): is a breath audible when the patient speaks?
A (asthenicity): is there a feeling of asthenia?
S (strain): is there an impression of the patient?
These five parameters are rated from 0 (normal voice) to 3 (maximum alteration of the voice). Scoring is relatively easy for hoarseness and breath, but it is difficult for asthenia and forcing.
Perceptual assessment of dysarthria
It consists of 32 criteria related to the volume and timbre of the voice, breathing, etc. A scale notes the severity of the criterion (0: no anomaly, 4: severe anomaly).
Several tests translated from English have been developed including the Assessment of Intelligibility in Dysarthric Speakers.
There are instruments that perform acoustic and aerodynamic measurements of speech. For example, the Assisted Voice Assessment device records certain physiological parameters of voice and speech (intensity, pitch, airflow, pressure). .