Aug. 16, 2008 -- Scott Adams is the cartoonist who gives Dilbert a voice -- a gift he wishes he could give himself.
"It feels like you're being strangled from the inside out," he told ABC News' David Muir.
That's right -- strangled. Adams said he literally chokes on his own words. It's a strange and isolating condition that began after what seemed like normal laryngitis.
"I couldn't talk normally for over a year," Adams said. "I still don't talk normally."
National Public Radio host Diane Rehm has been stricken with the bewildering condition as well.
"I was sounding so bad," she said, "I thought they must be thinking, 'What is this woman doing on the air?'"
And the radio host and cartoonist are not alone. Ken Michaels' voice is vanishing also. His wife, Raychene, said his voice sounds tremendously different.
All three say they've spent years searching for an answer and a cure. For nearly a century, the medical consensus was that this type of mysterious loss of voice was psychological. Doctors believed people suffering from it, for some reason, didn't want to talk.
But Michaels and the others say they'd do anything to speak normally again. "Primetime" traveled with Michaels as he visited Dr. Paul Flint, who finally gave him a correct diagnosis.
"It was obvious when he came in that he had spasmodic dysphonia," Flint said.
About 30,000 Americans suffer from this condition, also known as "strangled voice." Doctors believe it's caused when part of the brain misfires-- the same part that causes Parkinson's disease.
"Spasmodic dysphonia is a neurological condition that affects a patient's voice," Flint explained, "and it does so by creating abnormal tension within the throat muscles when they're trying to speak."
For Michaels, it was a great relief to finally know what was wrong with his voice. But not all the news he heard was good. Flint told him spasmodic dysphonia is manageable, but incurable. And the way he recommends treating it? Of all things -- Botox.
That's right -- botulinum toxin. The same poison used to paralyze facial muscles and erase those furrowed brows and wrinkles can apparently bring back your voice.
Flint explained that if the shots worked, Michaels' voice would come back gradually. It would never sound exactly the way it used to, but it would be fairly clear and strong, and the treatment should last for a few months. For Michaels, it was definitely worth a shot -- one directly into the vocal chords, to be exact.
Since the effects of Botox are fleeting, Diane Rehm's been getting shots in her neck about every three months for nearly 10 years. And they work well enough to keep her on the air.
About a month after Michaels' first injection, his voice was remarkably different. No more stops and starts. It was a nice, mellow baritone. Even he was surprised at the way his voice sounded just four weeks before.
"I didn't realize I sounded that bad," he said. "That's awful. I think I could see it on other people's faces, though, that they were trying hard to understand me."
Which is precisely why Scott Adams' wife, Shelly, requested he get a Botox injection before their wedding day.
"I wanted to make sure that he was able to say, 'I do.'" She told us. "I wanted to make sure it was clear."
And it was. But Adams wasn't completely satisfied with the results of Botox. He didn't like the sound of his voice with it. Not only that, the effects only lasted about a month in his case.
So Adams has been trying other options. Like something called direct voice rehabilitation. It's a kind of voice therapy created by Dr. Morton Cooper that uses humming and breathing techniques to teach people how to speak clearly again.
And though his voice has improved, it's still not back. He told "Primetime" that his voice was in the top 5 percent of its range the day he was interviewed. Adams said he usually has to struggle much more to get his words out.
So now, he's decided to take a drastic "last resort" -- a surgery to re-route the nerves to his vocal chords. It's an operation surgeons have been trying to perfect over the past ten years. There's a risk that it may leave Adams with little or no voice at all. But if successful, it may finally bring his voice back for good. He won't know for months, when the nerves have had a chance to heal.
In the meantime, Adams has discovered an irony in all this. His comic strip characters, Dilbert and Dogbert, are also missing something -- their mouths. But they still have a voice. And he hopes he'll get his back too.
For more information, visit the National Spasmodic Dysphonia Association.