The term 'Stroke' for what is nowadays called a cerebrovascular accident (CVA; meaning blockage of a the brain arterial supply by a thrombus or embolus; or brain destruction from a cerebral hemorrhage) derives from the term "Elf-Stroke" or "Fairy-Stroke".
The belief was that when a person collapsed with a paralytic seizure, and immediately or soon died, he had been struck with Elf-Shot (from a flint-headed arrow or dart) or some other kind of elf-blow.
His real body and soul had been invisibly taken by the elves, and replaced with a 'Stock' - perhaps a piece of wood, or a replica; which if not already inert would soon cease to move.
This information comes from A Dictionary of Fairies by Katharine Briggs, 1976. Dr Katharine Mary Briggs - MA, DPhil, DLitt Oxon. - (dates 1898-1980) was President of the English Folklore Society.
