Aphasia (In a Page: Signs and Symptoms)

Aphasia (In a Page: Signs and Symptoms)


Excerpt about 'Aphasia' from the book "In a Page: Signs and Symptoms" (Copyright © 2007 Lippincott Williams & Wilkins)


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.

▲TopDifferential 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

▲TopWorkup 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

▲TopTreatment

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