There are seven types of dysarthria, each with their own causes and features (see below). Dysarthria is motor speech disorder caused by damage to the central and/or peripheral nervous system. Each type of dysarthria results in a different pattern of impairment in the muscle control of the speech mechanism.
People with dysarthria may have problems with respiration (breathing), phonation (voicing), articulation (speech), prosody (patterns of stress and intonation) and resonance (e.g. nasality). Treatment usually focuses on managing these problems, with priorities set collaboratively by the client, his or her family members, and the therapist.
Features of the seven kinds of dysarthria can be outlined as follows:
|Type||Cause||Typical speech and voice symptoms|
|Spastic||Bilateral damage to the upper motor neurons (direct and indirect pathways).||Spasticity, facial weakness, reduced range of movement and slowness, increased muscle tone, hyperactive gag reflex, monopitch and loudness, breathy and harsh voice, hypernasality.|
|Flaccid||Lower motor neuron damage to cranial or spinal nerves supplying speech muscles.||Muscle weakness, atrophy, diminished reflexes, twitches of resting muscles (fasciculations), rapid fatigue with use, respiratory, phonatory and resonance disorders (including a breathy voice and frank hypernasality), and articulation disorders (especially if the cranial nerves supplying the jaw, face and tongue are involved).|
|Ataxic||Damage to the cerebellum.||Instability of the head, uncoordinated, jerky and halting articulation. Imprecise consonants, breakdowns, and distortions of vowels. Excessive and unusual stress patterns. Monopitch, monoloudness, harshness of voice. Some people with ataxic dysarthria may "sound drunk", and be discriminated against, accordingly.|
|Hypokinetic||Damage to the basal ganglia, commonly associated with Parkinson's disease.||Tremors in the face, mouth and limbs that dimish when moved voluntarily, a mask-like face with infrequent blinking, monopitch and a very soft voice, reduced stress, short rushes of speech and an increased rate.|
|Hyperkinetic||Damage to the basal ganglia.||Movement disorders, e.g. abnormal and involuntary movements of the orofacial muscles, tics of the face and tremors, voice tremor, intermittent hypernasality, inconsistent articulation problems.|
|Mixed||2 or more dysarthrias. The two most common types are flaccid-spastic (associated with amyotrophic lateral sclerosis) and ataxic-spastic (associated with multiple sclerosis).||Symptoms include major problems of the different types of dysarthria that are mixed.|
|Unilateral Upper Motor Neuron||Damage to the upper motor neurons that supply cranial and spinal nerves involved in speech.||Unilateral lower facial weakness, unilateral tongue weakness, unilateral palatal weakness, articulation disorders, harsh voice, reduced loudness, slow rate, short phrases, hypernasality. Because of the location of the damage, often people with this kind of dysarthria often also have aphasia and AoS.
In practice, the correct diagnosis and treatment of dysarthria is a lot more complicated than the table above suggests.
Banter Speech & Language is owned and managed by David Kinnane, a Hanen- and LSVT LOUD-certified speech-language pathologist with post-graduate training in the Spalding Method for literacy, the Lidcombe and Camperdown Programs for stuttering, and Voicecraft for voice disorders. David is also a Certified PESL Instructor for accent modification.
David holds a Master of Speech Language Pathology from the University of Sydney, where he was a Dean’s Scholar. David is a Practising Member of Speech Pathology Australia and a Certified Practising Speech Pathologist (CPSP).