Aetiology

The most common cause of dysarthria is alcohol intoxication.

Other causes include:

• cerebellar disease: causing a scanning dysarthria
• extrapyramidal disease: causes monotonous speech since it causes bradykinesia and muscular rigidity
• bulbar or pseudobulbar palsy
  • bilateral lower cranial nerve lesions of cranial nerves IX, X or XII cause a nasal speech, e.g. motor neurone disease, bulbar polio, syringobulbia, medullary tumour, Guillain-Barre syndrome
  • bilateral upper motor neurone of cranial nerves IX, X or XII causes a spastic dysarthria, e.g. cerebral ischaemia, motor neurone disease, multiple sclerosis
• paralysis or weakness of facial muscles: causes slurred speech
• oral lesions, e.g. mouth ulceration, loose dentures