Missy Elliott battling Graves' disease

Los Angeles - Missy Elliott has secretly been battling Graves' disease.

The Get Ur Freak On star said the autoimmune disease affected her so badly she was physically unable to write, causing her to step away from the spotlight after she was diagnosed in 2008.

She told People magazine: "I was driving, trying to put my foot on the brake, but my leg was jumping. I couldn't keep the brake down and almost crashed.

"I couldn't write because my nervous system was so bad - I couldn't even use a pen."

Symptoms of the disease, which affects the thyroid, include mood swings and weight loss.

No cure

Missy, 39, has undergone radiation therapy and while there is no cure, her condition has improved.

She added: "I'm 30 pounds lighter because I've been exercising. My thyroid is functioning, so I haven't had to take medication in about nine months. But you live with it for the rest of your life."

The female rapper is now well enough to go back to the studio however, and added is currently working with long-term collaborator, producer Timbaland.