Afasias

Afasias are a group of language disorders caused by damage to language-dominant regions of the brain, most often the left hemisphere in right-handed people. They affect speech production, comprehension, reading, and writing, with deficits that vary by type. Afasias are typically acquired after brain injury, rather than developmental.

Common types include Broca's aphasia, which features nonfluent speech with relatively preserved comprehension; Wernicke's aphasia, characterized by fluent but often nonsensical speech and impaired understanding; global aphasia, with severe impairment across language modalities; conduction aphasia, where speech is fluent and comprehension is relatively intact but repetition is impaired; and anomic aphasia, marked by prominent word-finding difficulties despite fluent speech and good comprehension.

Most afasias result from brain injury that disrupts language networks, with stroke being the most frequent cause. Other causes include traumatic brain injury, brain tumors, infections, and progressive neurodegenerative diseases. Onset is typically abrupt after an injury, though some conditions produce gradual changes.

Diagnosis involves a language assessment by a speech-language pathologist and neuroimaging to localize the lesion, usually using CT or MRI. Diagnosis guides therapy and prognosis.

Treatment centers on intensive speech-language therapy aimed at restoring language skills and teaching compensatory strategies. Therapy often involves practice with naming, speech production, comprehension, reading, and writing, along with training for families and caregivers. Pharmacologic treatments have been explored but show mixed evidence; outcomes frequently depend on lesion location and size, timing of intervention, and overall health.