Stephen said: “I was sitting quietly alone in the house one evening and I suddenly heard this quite loud scratchy noise, like sandpaper being rubbed on wood.

“I was quite alarmed and looked around, wondering what it was. Then I noticed the noise came every time I moved my eyes. I started to think I was going mad.” He went on: “The first symptoms appeared around 2005. I found if I raised my voice I’d get a vibration in my head.