Apoplexy is a sudden and often fatal fit resulting from blood vessels bursting in the brain. The 19th century character Madame Bovary became a widow because of it. Today, we generally call it "a stroke," but apoplexy sounds way better.
Although apoplexy as a specific medical term is not such a common term now, the word apoplectic certainly is, meaning furious and red-faced with uncontrollable rage (so called because its symptoms of flushed red face and loss of bodily control mimic those of apoplexy). Often used humorously — apoplectic is how you might describe your parents when they see your grades — though there's nothing funny about a real apoplectic fit.