Aphasia

Aphasia: Excerpt from In a Page: Signs and Symptoms

Aphasia refers to the inability to understand or express written or spoken words, despite preservation of the mechanical or visual means to do so; thus, facial weakness, oropharyngeal paresis, or primary disturbances of vision and hearing do not constitute aphasia. To localize the lesion within the cerebrum, aphasias are generally separated into receptive (Wernicke's aphasia) or expressive (Broca's aphasia) types. Further subgroups include anomic, conduction, and transcortical sensory, and transcortical motor.

Differential Diagnosis

• Stroke is the most common cause of aphasia
  –Sudden onset suggests cerebral embolization from a cardiac (e.g., endocarditis, atrial fibrillation) or carotid artery source
  –A stuttering onset suggests in situ arterial thrombosis
• Less common etiologies include Alzheimer's dementia, postconcussion syndrome, Rasmussen's encephalitis, nonconvulsive status epilepticus, dissociative state, subdural hematoma, trauma, severe hypoglycemia, sedative-hypnotic drug intoxication, sensorineural hearing loss, herpes encephalitis, and tertiary syphilis

Types of aphasias
• Receptive (Wernicke's) aphasia
  –Inability to name objects, follow written or spoken commands, and repeat
  –Verbal (semantic, neologistic) errors are abundant; however, speech is fluent
  –Localized to the dominant posterior superior temporal lobe
• Expressive (Broca's) aphasia
  –Stuttering, nonfluent speech with literal (phonemic) errors; however, comprehension is preserved
  –Repetition is poor, but naming is preserved
  –Associated with hemiparesis
  –Localized to the inferior lateral dominant frontal lobe

• Anomic aphasia
  –Isolated inability to name a seen object
  –Localized to the angular gyrus
• Conduction aphasia
  –Isolated inability to repeat
  –Localized to the arcuate fasiculus (white matter band connecting Wernicke to Broca areas)
• Transcortical sensory aphasia
  –Similar to Wernicke's aphasia, except for preserved repetition
  –Localized to the superior posterior temporal lobe
  • Transcortical motor aphasia
    –Similar to Broca's aphasia, but with preserved repetition, including urinary incontinence, echolalia (aimlessly repeating other's spoken words)
    –Localized to medial dominant frontal lobe

  Workup and Diagnosis

  • History and physical examination
    –History should include a complete past medical history, family history, psychiatric history, and medication history
    –Exam should include a comprehensive neurologic exam, cardiovascular exam, and head and neck exam
    –Fever and headache with aphasia suggests embolization from endocarditis or herpes simplex encephalitis
    –Gradual onset with other signs of intellectual decline suggests dementia
  • The cornerstone of diagnosis is cerebral imaging (MRI has the highest sensitivity and specificity)
  • Initial laboratory tests should include CBC, electrolytes, BUN/creatinine, calcium, glucose, RPR, and vitamin B₁₂ level
  • Consider toxicology screen
  • Echocardiography (transesophageal echocardiogram is best) and blood cultures may be indicated to diagnose endocarditis
  • CSF analysis and EEG to diagnose viral encephalitis versus status epilepticus
  • Psychometric testing necessary for dementia
  • Normal brain imaging with or without associated psychiatric signs may suggest status epilepticus, hypoglycemia, or a dissociative state

  Treatment

  • Embolic stroke: Anticoagulation; however, if secondary to endocarditis, do not initiate anticoagulation, because of increased risk of hemorrhage; instead, treat with antibiotics
  • Thrombotic stroke: Antiplatelet therapy (e.g., aspirin or clopidogrel) and risk factor reduction (e.g., lipid and hypertension therapy)
  • Viral encephalitis: IV acyclovir for 10–14 days
  • Dementia: Acetylcholinesterase inhibitors are of variable effectiveness in Alzheimer's disease
  • Status epilepticus: IV lorazepam and anticonvulsants
  • Hypoglycemia and other electrolyte abnormalities: Correction of underlying metabolic problem
  • Dissociative state: Oral or IV benzodiazepines may “break the spell” of psychiatric separation of attention from the environment; ECT may be necessary
  • Speech therapy is useful to help maintain motivation to improve language function and avoid depression from communication impairment

Book Source Details

• Book Title: In a Page: Signs and Symptoms
• Author(s): Scott Kahan, Ellen G. Smith
• Year of Publication: 2004
• Copyright Details: In a Page: Signs and Symptoms, Copyright © 2004 Lippincott Williams & Wilkins.

More About Nielsen-Jacobs syndrome

• Back to disease: Nielsen-Jacobs syndrome: Introduction
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

More About This Book: Title: In a Page: Signs and Symptoms Authors: Scott Kahan, Ellen G. Smith Publisher: Lippincott Williams & Wilkins Copyright: 2004 ISBN: 1-4051-0368-X

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