WASHINGTON (AP) — Ann Romney, the wife of Republican presidential candidate Mitt Romney, had a "real scare" from a "little bitty" flare-up of her multiple sclerosis during the spring, the result of the stress and strain of her husband's political campaign.

"It was just a reminder that I can't keep up the pace," she said Thursday on NBC's "Rock Center."

The flare-up occurred in March during the primaries. Mrs. Romney said she didn't tell anyone at the time because she "didn't want to have anyone worry about me, especially Mitt," when she started "feeling tingling and a little bit of numbness coming back, and I started getting dizzy."

Mrs. Romney was diagnosed in 1998 with multiple sclerosis, an autoimmune disease that affects the central nervous system. Her condition has been in remission since she received a year of aggressive treatments of intravenous steroids. But flare-ups can occur under constant stress — the kind a national political campaign can create.

Mrs. Romney's recent interviews have put her on display cutting through the campaign din, including her blunt statement that her husband has provided everything that "people need to know" and won't be releasing more tax returns.

Although Mrs. Romney is still largely unknown to a large portion of the public she is well regarded by GOP voters. Mrs. Romney, for her part, has increasingly been out front, fielding questions on issues at the core of her husband's campaign — his choice for vice president, his refusal to release additional tax returns and more. She's also a potent fundraiser.