Types of aphasia

What it is

Aphasia is an impairment of language function. The types are separated by three features: fluency, comprehension and repetition.

Causes and risk

In MCA infarcts, the dominant hemisphere gives aphasia and agraphia, while the non-dominant hemisphere gives hemi-spatial neglect and impaired cortical sensations, that is localization, 2 point discrimination, stereogenesis and graphesthesia. The same infarct gives contralateral hemiplegia and contralateral hemi-sensory loss with face and arm affected more than leg, and contralateral homonymous hemianopia, or homonymous quadrantanopsia, with ipsilateral gaze preference. Aphasia is one of the cortical signs whose absence marks a lacunar stroke, with agnosia, neglect, apraxia and hemianopia. Aphasia, apraxia and agnosia are features of Alzheimer's disease, and progressive non-fluent aphasia is a feature of Pick disease, frontotemporal dementia. Aphasia is also seen with a focal brain lesion. Two cases describe a 33 year old man brought to the hospital because of a seizure who, as he becomes more alert, has aphasia and weakness of the right hand and leg, with a CT scan of the head with contrast: in one he was HIV-negative with enhancement of the lesion and a ring around it, in the other HIV-positive with multiple rings enhancement lesions and a CD4 of 44.