'Spice Girl' speaks out about her condition.
Lianne Morgan's condition - called Spasmodic Dysphonia - means her voice cuts off when she speaks because of muscle spasms.
But in an astonishing twist, the 41-year-old mum can still sing.
Lianne, who was taken out of the original Spice Girls line up a month after joining to be replaced by Melanie C, said that her condition had been growing worse for the last four years.
The mum to Jacob, nine, and Aled, five, said: "I started experiencing problems around four years ago. I had a really bad throat and chest infection and my voice remained like a croak after that.
"I was teaching singing to large groups and every time I tried to raise my voice it would just cut off so I had to leave. I then decided to try to take things easy and rest my voice but it only seemed to get worse."
Eventually, a specialist diagnosed Spasmodic Dysphonia, telling Lianne there was no cure.
She said: "It is nothing to do with my vocal chords but the message centre from my brain that sends the signal to my vocal chords is not working properly.
"But singing is different.
because it's a different part of the brain that's used and completely different mechanics."
To hear Lianne sing, go to www.liannemorgan.co.uk