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How can a stroke affect a person’s ability to use language?

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functional areas of the human brain — speech disorder Functional areas of the human brain.

A stroke can affect a person’s ability to use language primarily by causing aphasia or dysarthria, depending on the location and extent of the brain damage.123

Aphasia

Aphasia is a disorder of language expression and comprehension resulting from damage to the brain's language centers, often in the left hemisphere.143
* Broca aphasia: Caused by damage to the frontal lobe, this results in difficulty expressing thoughts. Individuals may speak in short, "telegraphic" phrases while retaining comprehension.14
* Wernicke aphasia: Caused by damage to the temporal lobe, this affects comprehension. Speech may be fluent but "garbled," often described as "word salad" empty of meaningful content.143
* Global aphasia: Extensive damage can lead to a total or near-total loss of both expressive and receptive language functions.13

Dysarthria

Unlike aphasia, which is a language disorder, dysarthria is a motor speech disorder. A stroke can damage the nerves or brain regions that control the muscles used for speech production, such as the lips, tongue, and jaw. This leads to symptoms like slurred, slow, or breathy speech, as well as difficulty with articulation and volume control.4526