“Aphasia is a disorder that affects how you communicate. It can impact your speech, as well as the way you write and understand both spoken and written language.
Aphasia usually happens suddenly after a stroke or a head injury. But it can also come on gradually from a slow-growing brain tumor or a disease that causes progressive, permanent damage (degenerative). The severity of aphasia depends on a number of things, including the cause and the extent of the brain damage.”
MAYO CLINIC (https://www.mayoclinic.org/diseases-conditions/aphasia/symptoms-causes/syc-20369518)