Dysarthria

Overview
Dysarthria is a speech disorder resulting from neurological injury, characterised by poor articulation (cf aphasia: disorder of the content of speech). Any of the speech subsystems (respiration, phonation, resonance, prosody, articulation and movements of jaw and tongue) can be affected.

Disarthic speech is due to some disorder in the nervous system, which in turn hinders control over for example tongue, throat, lips or lungs. Swallowing problems, dysphagia, are often present.

Cranial nerves that control these muscles include the facial nerve (VII), the glossopharyngeal nerve (IX), the vagus nerve (X), and the hypoglossal nerve (XII).

Classification
Dysarthrias are classified in multiple ways based on the presentation of symptoms. Specific dysarthrias include Spastic, Flaccid, Hyperkinetic, Hypokinetic, Ataxic, Unilateral upper motor neuron, and Mixed dysarthria.

Causes
The reasons behind dysarthria can be many; among the diseases are ALS, Parkinson's disease, botulism, cranial nerve lesions, chorea, prion protein related diseases, and cerebral palsy. Dysarthria can also be an early symptom of stroke, and of other forms of traumatic brain injury. More common causes are intoxication and anesthesia, although these are transient. Another possibility is myasthenia gravis.

Complete Differential Diagnosis of Dysarthria
In alphabetical order.

Neurological

 * Abscess
 * Amyotrophic Lateral Sclerosis (ALS)
 * Botulism
 * Brainstem stroke
 * Dermatomyositis
 * Diabetic nerve infarction
 * Hypothyroidism
 * Mitochondrial disease
 * Myasthenia gravis
 * Myotonic muscular dystrophy
 * Nerve gas/ organophosphate poisoning
 * Parkinson's Disease
 * Polymyositis
 * Prolonged effects of anesthesia
 * Stroke
 * Tumor

Structural

 * Tumors:
 * Lips
 * Squamous cell epithelium of the oropharynx and vocal cords
 * Tongue

Less Common Etiologies

 * Acute dystonic reaction
 * Amyloidosis
 * Anaerobic infection
 * Cleft palate
 * Mild cerebral palsy
 * Poor dentition or ill-fitting dentures
 * Sedative/anticonvulsant intoxication
 * Unrecognized foreign accent

Treatment
The articulation problems that dysarthria causes can be treated together with a speech language pathologist using a range of techniques which sometimes includes strengthening the speech musculature. Devices that make coping with dysarthria easier include speech synthesis software and text-based telephones.