"Speaking with them, we all did the same thing; we just let go of any social life at all because you couldn't talk," she said.
Rappaport gets worried when she thinks others are going undiagnosed as well.
"I have heard certain people both on television and in my social life that I guessed had a problem and probably didn't know," she said.
"I've thought of dropping [Kennedy] a note," said Rappaport, who happens to live 20 minutes away from the Kennedy home on Cape Cod.
But Kennedy does know about spasmodic dysphonia. According to a spokesman for the NSDA, he's an honorary board member.
"It's a very rare disorder, and there is really very little known about it -- especially back in the '80s and '90s," said Dr. Phillip Song, a laryngologist at the Massachusetts Eye and Ear Infirmary in Boston. "The NSDA has gotten well organized, so you don't see people go undiagnosed for years as much."
People with spasmodic dysphonia in the media, such as Kennedy or National Public Radio talk show host Diane Rhem, have helped bring spasmodic dysphonia to national attention. Kennedy and Rhem both serve as honorary board members of NSDA, and Rhem wrote about her experience in her 2002 book, "Finding My Voice."
Still, Song and other experts warn there are only a few hotbeds of treatment in Boston, New York, Chicago and California. Everywhere in between, especially outside of metropolitan areas, people with spasmodic dysphonia may be suffering and unaware, just like Rappaport first was.
By the early 1990s, Rappaport found treatment for her condition in a National Institutes of Health clinical trial using Botox injections. The NIH flew her to Maryland from California to receive the low-dose injections, and she started to see an improvement.
Only years before, in 1986, Dr. Andrew Blitzer in New York City and others discovered Botox as a nonsurgical treatment for spasmodic dysphonia. Previously, doctors tried to crush or cut the nerve leading to the vocal folds and could only provide a few years of relief before the symptoms returned.
"If you do anything surgical, the dystonia tries to win. It tries to figure out a way around its obstruction," said Dr. Robert Bastian, spokesman for the NSDA and a Chicago-based specialist in treating spasmodic dysphonia.
Song and Bastian say doctors don't know what exactly causes spasmodic dysphonia, but they do know that treating the nerves at the vocal cords can only help, not cure the problem.
The best guess spasmodic dysphonia experts have for now is that root of the neurological disorder lies in the basal ganglia. The basal ganglia is often called the "processing area" of the brain and it sits between the cortex -- the "upper management" part of the brain as Song calls it -- and the brain stem, or the "foot soldier" of the brain.
However, the most advanced research is still focused on finding physical evidence of changes in the brain, and possibly a genetic cause behind the disorder. For now, most spasmodic dysphonia patients work with the cycle of low-dose Botox treatments three times a year that leave their voices first as breathy, then normal then stilted again.
Rappaport falls among the one in 10 people with spasmodic dysphonia who suffer from the from abductor form, which is more difficult to treat with Botox than adductor dysphonia. Instead of sounding strained and stilted, she sounds breathy and weak.
Rappaport decided to stop Botox treatments for fear of building immunity -- although most doctors say the low dose in spasmodic dysphonia treatments is unlikely to cause this.
"It's not good, it's not perfect, but I can make myself understood and that's what matters," Rappaport said. "But I do want to help people understand this -- you become less credible because people don't know what's wrong with you."