One day as many others. Sarah was 18 and was at school. She had just started reading aloud in front of her school mates, when she suddenly lost the ability to use language.
Sarah was having a stroke.
Stroke is the medical term for when a part of the brain is damaged because of a problem with the blood supply to the brain. It can happen when an artery that provides blood supply to the brain gets clogged or breaks open, and part of the brain stays without blood for too long.
Depending on which area of the brain is affected, the effects of a stroke can be broad (i.e. many faculties can be impaired) or very limited.
What happened to Sarah is called Aphasia: the stroke affected the area of the brain that regulates language production. There are many types of Aphasia. The one that happened to Sarah is called Broca’s Aphasia and is characterized by impaired speech, normal or slightly altered comprehension and impaired writing, generally in proportion to fluency loss.
If you wish to know more about stroke but are not familiar with medical terms, check the websites of the American Stroke Association and the American Heart Association. You will find plenty of accurate and useful information in plain language, written by doctors for patients.