"I don't feel so alone," she tweeted
Wednesday, thanking fans for their support.
Sigler, 34, told People
that she was diagnosed with the debilitating disease when she was 20 but didn't want to reveal that she had it until now.
"I wasn't ready until now," People quoted her as saying. "You'd think that after all these years, somebody would be settled with something like this, but it's still hard to accept."
Sigler said she decided to let her fans in on her struggle now, just days after marrying Cutter Dykstra, with whom she has a 2-year-old son.
"I'm at a point in my life with my son, with my new marriage, it's a new me," she told People. "I don't want to hold a secret where it feels like I have something to be ashamed of or have something to hide."
Sigler, best known for her role as Meadow Soprano on the 1999-2007 HBO series "The Sopranos," said the initial diagnosis came as something of a shock. She says she didn't feel sick at the time.
She has since struggled with symptoms of MS, a disease of the central nervous system that can cause vision problems, issues with balance and coordination, fatigue, tremors and memory issues, among others.
"I can't walk for a long period of time without resting. I cannot run. No superhero roles for me," People quoted her as saying.
She also said stairs can be a problem for her.
"I can do them but they're not the easiest," she said. "When I walk, I have to think about every single step, which is annoying and frustrating."
She said medication has helped hold the symptoms at bay for the past six years.
Sigler said she hopesthat speaking out will help advance research on the disease and a cure.