aphasia

Aphasia is an inability to comprehend or formulate language because of damage to specific brain regions. The major causes are a cerebral vascular accident (stroke), or head trauma, but aphasia can also be the result of brain tumors, brain infections, or neurodegenerative diseases such as dementia. However, the latter are far less common and so not as often mentioned when discussing aphasia.[2] To be diagnosed with aphasia, a person's speech or language must be significantly impaired in one (or more) of the four aspects of communication following acquired brain injury, or have significant decline over a short time period (progressive aphasia). The four aspects of communication are auditory comprehension, verbal expression, reading and writing, and functional communication. https://en.wikipedia.org/wiki/Aphasia