What is dysarthria?

Dysarthria is a disorder caused by paralysis, weakness, or inability to coordinate the muscles of the mouth. Dysarthria can occur as a developmental disability. It may be a sign of a neuromuscular disorder such cerebral palsy or Parkinson disease. It may also be caused by a stroke, brain injury, or brain tumor. The involvement of these different parts of the speech production and mechanism may vary. Dysarthria occurs in a number of neurological conditions and can be the result of brain disfunction or injury. This means that it may be part of a developmental speech condition (present from birth) or an acquired condition (as a result of the onset of a particular neurological condition or after brain injury).

Dysarthria is the second most common speech disorder among elderly patients. It may be ataxic, flaccid, hyperkinetic, hypokinetic, spastic, or mixed. Causes include poor coordination of the lips, tongue, palate, vocal cords, or respiratory muscles due to neurologic diseases (eg, stroke, head trauma, cranial surgery, amyotrophic lateral sclerosis, multiple sclerosis, cranial nerve palsies) and to lesions that affect the speech mechanism (eg, vocal cord tumors). Dysarthria can range in severity from mild, through moderate to severe. Speech patterns may have a number of different characteristics depending on the nature of the damage to the brain. The speed of speech production may be affected. Most commonly speech is slow, but sometimes quick involuntary movements affect speech production. All movements may be slow and limited in range. Those with sever dysarthrias may have no movement at all in some organs which are required to move in a controlled way for clear speech production.

Dysarthria is also called Worster-Drought syndrome. This is more appropriate where it is congenital and non-progressive and is associated with mild general motor problems and some general learning problems. The condition may run in families and an early history of poor sucking and swallowing is usual. There may be difficulties in introducing solid food. The usual pattern is of weakness and problems controlling the voluntary movement of the lip muscles, tongue, soft palate and, when more severe, the pharyngeal and laryngeal muscles. Speech usually sounds very 'nasal', slurred and indistinct, but children can be anarthric (i.e. unable to develop useful movement for speech).

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