He's starting to lose his balance and peripheral vision. The 50-year-old has very little short-term memory, and the formerly glib salesman now struggles to remember and pronounce words like "raspberry" in simple conversation. And the headaches are so severe, he doesn't want to get out of bed.

It's because the left side — and only the left side — of his brain is shrinking, and has been for about 10 years.

"Every once in awhile, I realize, 'Gee, I can't do that anymore,"' Mitchell said.

Doctors do not have a clue why this is happening, and say normally suspect causes — like multiple sclerosis or Alzheimer's disease — are not at play here because they would equally shrink both sides of the brain.

But in Mitchell's case, the left side of his brain is 10 percent smaller than the right.

"That's very, very uncommon," Dr. Juan Troncoso, associate professor of pathology and neurology at Baltimore's Johns Hopkins University, said of Mitchell's condition. "There are cases described of degenerative diseases that are dominant on one side of the brain. But then, over 10 years of progression, you'd expect the other side to have some kind of abnormality."

Mitchell is scheduled to have a brain biopsy at the Mayo Clinic in Rochester, Minn., later this month, a procedure that could be fatal.

Even though there is no guarantee it will uncover the cause of his shrinking brain, both Mitchell and his wife, Cynthia, said he has to try.

"I just don't want to sit there and not do anything," he says.

Mitchell's rare case has been featured at medical symposiums, but still hasn't produced a diagnosis.

He's seen about 15 neurologists, who have performed a battery of tests but found no answers.

"It was puzzling to the physicians," said Dr. Patrice Duvernay, a neurologist for 카지노사이트 - http://kaizenlogistics.vn/ Intermountain Health Care in Salt Lake City who has treated Mitchell.

Duvernay said the left side of his brain will continue to slowly shrink until doctors find a solution.

The shrinkage is only visible by looking at an MRI or CT scan, but what's going on inside his skull has taken a big toll on Mitchell's quality of life.

He can watch a movie a hundred times and still not remember how it ends.

His wife can tell him to be ready in a half an hour to visit a friend's house, and within 15 minutes he will have no idea why she's disappointed that he's not dressed.

The condition has completely changed Mitchell's personality - http://www.encyclopedia.com/searchresults.aspx?q=personality . He now sleeps 12-14 hours a day, and said before he never slept more than six.

Sleeping and staying in bed about two days a week, he says, is one of the only ways to escape the constant headaches. A cabinet full of pain medication doesn't help.

Cynthia has seen her husband transform from a runner and hiker to a shy shut-in.

"It's hard, because David used to be such a vibrant extrovert," said Cynthia, who knows when her husband is having a bad day because there is a bulging vein in his forehead.

Mitchell also no longer enjoys socializing, because it frustrates him to probe for words while others wait.

"It's too hard to do it," Mitchell says. "I'm a lot quieter with people I don't know that well."

Another problem facing the couple is that they no longer have medical insurance. They say they were dropped after missing a recent payment.

Cynthia Mitchell estimated they will have racked up about $100,000 in bills by the time he has the biopsy. Neither a fund-raiser nor an account set up at a local bank has brought in much relief.

Despite worries over money and health, the Mitchells - https://www.behance.net/search?content=projects&sort=appreciations&time=... remain amazingly upbeat.

They have learned to laugh when David Mitchell forgets things, like how to tell the difference between a club and a spade on playing cards (he has to be reminded that spades don't have the "things sticking out").

"We laugh. We have to, or we'd cry," Cynthia Mitchell says.