New Delhi, Aug. 18 -- Is it possible to give someone their voice back after nearly two decades of silence? One remarkable case from Canada is prompting fresh hope for those living with locked-in syndrome and other paralysis-related speech loss, showing just how far brain-computer interfaces have come.

Ann Johnson was only 30 when everything changed. Working as a high school teacher, newly married, and a mother, she suddenly suffered a brainstem stroke while playing volleyball in 2005. The result was devastating: total paralysis and an inability to speak, a condition known as locked-in syndrome. She was fully aware but cut off from the world except through the slow movement of her eyes.

For eighteen years, Johnson's voice was silent. The...