Dysarthria

Dysarthria is a motor speech disorder. 

This results in impaired articulatory ability, speech that is slowed, slurred or distorted.

Etiology:

Difficulty in forming words or speaking them because of weakness of muscles used in speaking or because of disruption in the neuromotor stimulus patterns required for accuracy and velocity of speech, such as neurological injury.

Alcoholic cerebellar degeneration

This disorder commonly causes chronic, progressive dysarthria along with ataxia, diplopia, ophthalmoplegia, hypotension, and altered mental status.

Amyotrophic lateral sclerosis

Dysarthria occurs when this disorder affects the bulbar nuclei; it may worsen as the  disease progresses. Other signs and symptoms include dysphagia; difficulty breathing; muscle atrophy and weakness, especially of the hands and feet; fasciculations; spasticity; hyperactive DTRs in the legs; and occasionally excessive drooling. Progressive bulbar palsy may cause crying spells or inappropriate laughter.

Basilar artery insufficiency

This disorder causes random, brief episodes of bilateral brain stem dysfunction, resulting in dysarthria. Accompanying it are diplopia, vertigo, facial numbness, ataxia, paresis, and visual field loss, all of which can last from minutes to hours.

Botulism

The hallmark of this disorder is acute cranial nerve dysfunction that causes dysarthria, dysphagia, diplopia, and ptosis. Early findings include dry mouth, sore throat, weakness, vomiting, and diarrhea. Later, descending weakness or paralysis of muscles in the extremities and trunk causes hyporeflexia and dyspnea.

Multiple sclerosis

When demyelination affects the brain stem and cerebellum, the patient displays dysarthria accompanied by nystagmus, blurred or double vision, dysphagia, ataxia, and intention tremor. Exacerbations and remissions of these signs and symptoms are common. Other findings include paresthesia, spasticity, intention tremor, hyperreflexia, muscle weakness or paralysis, constipation, emotional lability, and urinary frequency, urgency, and incontinence.

Myasthenia gravis

This neuromuscular disorder causes dysarthria associated with a nasal voice tone. Typically, the dysarthria worsens during the day and may temporarily improve with short rest periods. Other findings include dysphagia, drooling, facial weakness, diplopia, ptosis, dyspnea, and muscle weakness.

Olivopontocerebellar degeneration

Dysarthria, a cardinal sign of this disorder, accompanies cerebellar ataxia and spasticity.

Parkinson’s disease

This disorder produces dysarthria and a monotone voice. It also produces muscle rigidity, bradykinesia, an involuntary tremor that usually begins in the fingers, difficulty walking, muscle weakness, and stooped posture. Other findings include masklike facies, dysphagia and, occasionally, drooling.

Shy-Drager syndrome

Marked by chronic orthostatic hypotension, this syndrome eventually causes dysarthria as well as cerebellar ataxia, bradykinesia, masklike facies, dementia, impotence and, possibly, stooped posture and incontinence.

Stroke (brain stem)

This type of stroke is characterized by bulbar palsy, resulting in the triad of dysarthria, dysphonia, and dysphagia. The dysarthria is most severe at the onset of the stroke; it may lessen or disappear with rehabilitation and training. Other findings include facial weakness, diplopia, hemiparesis, spasticity, drooling, dyspnea, and decreased LOC.

Stroke (cerebral)

A massive bilateral stroke causes pseudobulbar palsy. Bilateral weakness produces dysarthria that’s most severe at the stroke’s onset. This sign is accompanied by dysphagia, drooling, dysphonia, bilateral hemianopsia, and aphasia. Sensory loss, spasticity, and hyperreflexia may also occur.

Drugs

Dysarthria can occur when anticonvulsant dosage is excessive. Ingestion of large doses of barbiturates may also cause dysarthria.

Manganese poisoning

Chronic manganese poisoning causes progressive dysarthria accompanied by weakness, fatigue, confusion, hallucinations, drooling, hand tremors, limb stiffness, spasticity, gross rhythmic movements of the trunk and head, and a propulsive gait.

Mercury poisoning

Chronic mercury poisoning causes progressive dysarthria accompanied by weakness, fatigue, depression, lethargy, irritability, confusion, ataxia, and tremors.

Assessment:

If the patient displays dysarthria:

  • query associated difficulty swallowing
  • determine respiratory rate and depth.
  • measure vital lung capacity with a Wright respirometer if available.
  • assess blood pressure and heart rate
  • Tachycardia, slightly increased blood pressure, and shortness of breath are usually early signs of respiratory muscle weakness.

Management:

  • Ensure a patent airway.
  • Place the patient in Fowler’s position
  • Suction him if necessary.
  • Administer oxygen
  • Keep emergency resuscitation equipment nearby.
  • Anticipate intubation and mechanical ventilation in progressive respiratory muscle weakness.
  • Withhold oral fluids in the patient with associated dysphagia.

Follow-up:

  • If dysarthria isn’t accompanied by respiratory muscle weakness and dysphagia, continue to assess for other neurologic deficits.
  • Compare muscle strength and tone in the limbs, and evaluate tactile sensation.
  • Query patient about numbness or tingling.
  • Test deep tendon reflexes (DTRs), and note gait ataxia.

  • Assess cerebellar function by observing rapid alternating movement, which should be smooth and coordinated.
  • Test visual fields and ask about diplopia.
  • Check for signs of facial weakness such as ptosis.
  • Determine level of consciousness (LOC) and mental status (MMSE).

Springhouse. 2006. Professional Guide to Signs & Symptoms, Fifth Edition. Lippincott Williams & Wilkins.

Retrieved September, 29, 2009 from http://images.google.ca/imgres?imgurl=http://www.wrongdiagnosis.com/bookimages/8/2554.1.png&imgrefurl=http://www.wrongdiagnosis.com/symptoms/speech_symptoms/book-causes-8a.htm&usg=__VqUsn8CJgrQKcAtlSE3GQqqyAUQ=&h=654&w=497&sz=33&hl=en&start=2&um=1&tbnid=PpApdiKJHhMqfM:&tbnh=138&tbnw=105&prev=/images%3Fq%3Ddefine:Dysarthria%26hl%3Den%26sa%3DN%26um%3D1

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