Dysarthria
Dysarthria, poorly articulated speech, is characterized by slurring and a labored, irregular rhythm. It may be accompanied by a nasal voice tone caused by palate weakness. Whether it occurs abruptly or gradually, dysarthria is usually evident in ordinary conversation. It’s confirmed by asking the patient to produce a few simple sounds and words, such as “ba,” “sh,” and “cat.” However, dysarthria is occasionally confused with aphasia, loss of the ability to produce or comprehend speech.
Dysarthria results from brain stem damage that affects cranial nerves IX, X, or XII. Degenerative neurologic disorders and cerebellar disorders commonly cause dysarthria. In fact, dysarthria is a cardinal sign of olivopontocerebellar degeneration. It may also result from ill-fitting dentures. (See Dysarthria: Causes and associated findings, pages 256 and 257.)
Emergency interventions
If the patient displays dysarthria, ask him about associated difficulty swallowing. Then determine respiratory rate and depth. Measure vital 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.
Ensure a patent airway. Place the patient in Fowler’s position and suction him if necessary. Administer oxygen and keep emergency resuscitation equipment nearby. Anticipate intubation and mechanical ventilation in progressive respiratory muscle weakness. Withhold oral fluids in the patient with associated dysphagia.
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. Ask the 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. Next, test visual fields and ask about double vision. Check for signs of facial weakness such as ptosis. Finally, determine level of consciousness (LOC) and mental status.
History and physical examination
Explore dysarthria completely. When did it begin? Has it gotten better? Speech improves with resolution of a transient ischemic attack, but not in a completed stroke. Ask if dysarthria worsens during the day. Then obtain a drug and alcohol history. Also, ask about a history of seizures. Observe dentures for a proper fit.
Medical causes
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.
Other causes
Drugs
Dysarthria can occur when anticonvulsant dosage is too high. 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.
Special considerations
Encourage the patient with dysarthria to speak slowly so that he can be understood. Give him time to express himself, and encourage him to use gestures. Dysarthria usually requires consultation with a speech pathologist.
Pediatric pointers
Dysarthria in children usually results from brain stem glioma, a slow-growing tumor that primarily affects children. It may also result from cerebral palsy.
Dysarthria may be difficult to detect, especially in an infant or a young child who hasn’t perfected speech. Be sure to look for other neurologic deficits, too. Encourage a child with dysarthria to speak; a child’s potential for rehabilitation is typically greater than an adult’s.
Pictures
Book Source Details
- Book Title: Professional Guide to Signs & Symptoms (Fifth Edition)
- Author(s): Springhouse
- Year of Publication: 2006
- Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2006 Lippincott Williams & Wilkins.
Other Book Chapters Related to Slurred speech
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Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2008 Williams & Wilkins.
More About Causes of Slurred speech
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Aphasia/Dysarthria (Field Guide to Bedside Diagnosis)
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