After a stroke, individuals may experience various language problems such as aphasia, alexia, agraphia, and acalculia. Impaired writing skills (agraphia) and loss of reading skills (alexia) are common in stroke survivors. Alexia, also known as word blindness, text blindness, or visual aphasia, is often associated with aphasia, and individuals with aphasia often have alexithymia as well. Agraphia can occur alone or with other language problems, including aphasia, alexia, agnosia, and apraxia.

Aphasia is the most common language and speech disorder in individuals who have had a stroke. It is caused by brain damage and results in abnormal oral expression, difficulty in understanding spoken or written language, and impaired verbal abilities such as repetition, naming, reading, and writing.

Ischemic or hemorrhagic stroke in the anterior cerebral circulation region, particularly in the middle cerebral artery (MCA), is a common cause of aphasia. While the incidence of aphasia is 21-38% in the acute phase of stroke, it is still over 10% in the chronic phase. Spontaneous recovery is highest in the first three months after stroke, but long-term follow-up studies show that recovery can occur after years. The most common types of aphasia after stroke are Global, Broca, and Wernicke aphasia, respectively.

Global aphasia results from extensive lesions in the left hemisphere of the brain, including both Broca's and Wernicke's areas. It is the most serious and least curable speech disorder, affecting all areas of speech, and the affected individual is often only able to pronounce a few words. Spontaneous speech is not fluent, and the individual is unable to name, read, or write objects.

Broca's area, located in the left inferior frontal gyrus, corresponding to areas 44 and 45 of Brodmann, is responsible for language production, speech fluency, grammar, and sequencing. Broca's aphasia, also known as motor aphasia, occurs as a result of infarction of the superior division of the MCA in the dominant hemisphere. It is a speech disorder characterized by restricted speech production in short sentences containing only a few words. Auditory comprehension is often maintained, but understanding, naming, and repetition of complex grammatical structures and serial commands may be impaired.

Table : Classification of aphasia according to language and speech areas

References:

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