Ataxic dysarthria is one of several types of dysarthria. “Dysarthria is a group of motor speech disorders resulting from disturbed muscular control of the speech mechanism due to damage of the peripheral or central nervous system” (Hedge, 2001, p. 198). In specific, ataxic dysarthria is a disorder that affects the control of speech production due to damage to the cerebellum or the neural pathways that connect the cerebellum to other parts of the central nervous system.
McNeil (1997), states that an individual with ataxic dysarthria will have “drunken speech” which results from the particular vulnerability of the cerebellum (p. 217). The cerebellum may account for only ten percent of the brain’s volume, but it contains over fifty percent of the total number of neurons in the brain, which means that any damage to it can affect an individual’s motor speech. The cerebellum is responsible for coordination of movement and the process of sensory information. According to Knierim (1997), the cerebellum coordinates the timing and force of muscular contractions so that any skilled or voluntary movements can be appropriate for an intended task. It also processes sensory information from all over the body and assimilates that information into the execution of a movement. Above all, the cerebellum does not initiate any motor commands; it only modifies the movements that are being commanded.
There are many different things that can cause ataxic dysarthria. For example, any type of head trauma, or vascular lesion such as an aneurysm, arterial venous malformation, or hemorrhage in the brainstem or midbrain can cause damage to the cerebellum eventually leading to ataxic dysarthria. Degenerative diseases like multiple sclerosis, Friedreich’s ataxia, or Olivopontocerebellar atrophy are other causes of ataxic dysarthria. Hegde (2001) mentions, that tumors, hypothyroidism, or toxic conditions such as heavy metals can also be the cause of ataxic dysarthria.
An individual with ataxic dysarthria will not only have speech and voice problems, but will also have motor movement dysfunctions as well. The individual will have speech incoordination of timing, range, force, and speed, which will then lead to a “drunken” quality of speech. An individual with this disorder will complain about rapid deterioration of speech with limited alcohol intake, and problems coordinating their breathing and speaking (McNeil, 1997). Some motor dysfunctions that an individual with ataxic dysarthria will have are hypotonia, which is low muscle tone, and tremors. The individual will also have diadochokinetic impairment due the incoordination of speech movement. McNeil (1997) states, that an individual with this disorder will have respiratory problems, tongue and lip movement dysfunction, and phonation problems. Their breathing will be prolonged, and will have explosive intonations. The individual will have articulatory imprecision in both the tongue and lips, and phonemes are prolonged....