For 25 years, Lyn Culbert lived with the knowledge that her son's life would be far too short.

Dave Lewis was diagnosed at 14 with Friedreich's ataxia, a rare inherited neuromuscular disease that gradually eroded his balance, coordination and speech and damaged his heart. As an adult, he managed to live on his own, but in his final few years he needed an increasing amount of support.

Culbert was always there to provide it.

"He trained me how to help him," said Culbert, 71, who lives in St. Louis Park and has two other adult children.

A retired project manager, she was available to take Lewis to his many medical appointments. She communicated on his behalf when service providers either could not understand Lewis' faint and slurred speech or ignored him altogether. She got up in the middle of the night and drove the four miles to his house whenever he needed her.

Then, at age 39, Dave Lewis died.

"At the end of the year when he died, I was just beside myself. I thought, how can I go into a new year without him?" Culbert said, tearing up at the memory.

But her son still needed her help.

Lewis had spent about five years before he died writing a memoir about his disease. One day he asked Culbert for a favor. "If something should happen — you know, things happen — would you take care of getting my book published?"

Culbert promised that she would. "So I had an assignment, and it was a good thing."

Lewis was most of the way through a second revision of his book when he died. Culbert read through e-mailed notes he had exchanged with an editor he had met through the Loft Literary Center. She did her best to figure out how he wanted the book to go. Then she finished it for him.

The title, "There's Nothing Wrong With Asking for a Little Help … and other myths" reflects Lewis' determination to do things for himself whenever possible — except when he couldn't. Culbert chose a book cover created by her graphics-designer sister featuring a picture of Lewis wearing a fedora, looking confident — and maybe a bit skeptical.

She spent months contacting agents without much success and, after weighing the pros and cons, decided to self-publish the book. She chose Bright Side Books as the name of its publisher (www.bright-side-books.com) because "Dave always used to say you've got to look on the bright side."

Having a project to do as she was dealing with grief "was the best therapy," Culbert said. For one thing, when he died, Lewis' speech had deteriorated so much that he spoke in simple language to make himself understood. Reading the book "was like hearing his voice" the way it used to be, Culbert said. "There on the page, he's so articulate. It's such a gift to have his words."

The book was well received among ataxia sufferers, their families and physicians. Readers told Culbert they enjoyed Lewis' funny, conversational tone and determined spirit. Doctors bought multiple copies and gave them to their patients.

"People who have these problems laugh along with him when he's laughing, and cry along with him when he's crying," Culbert said. "It helps them feel less alone."

Culbert looked for other opportunities to help the ataxia community. She attended the annual national meeting of doctors who study and treat the disease. She volunteered for the control group in a research project on brain chemistry. She collaborated with doctors on a video about ataxia, featuring information about Lewis. Although Lewis himself had never joined an ataxia support group, Culbert did, and continued to attend meetings after he died.

Lately, Culbert has begun looking for new challenges. She no longer feels the need to go knock on every doctor's door and say, You must read this book." She still goes to the ataxia support group gatherings, but not as often.

She believes the skills she developed helping her son could be applied in other ways. She has long been a volunteer at Courage Kenny Rehabilitation Institute. She's in training to assist with in-home telemedicine visits ("like Skyping with your doctor"), performing tasks like taking blood pressure. She is familiar with some of the struggles people with disabilities endure — from transportation problems, especially in winter, to having others speak to their non-disabled relatives rather than directly to them — and would like to apply that knowledge elsewhere.

"There are so many more diseases, there are so many kids that have this problem and that," she said. "As important as ataxia is, it's just disability awareness and how to treat people. … I keep an open mind to what I can do."

Meanwhile, when she thinks about her son, she makes an effort — "I'm not always successful" — to remember the good times. Not the harrowing days at the end of his life, nor the period during his adolescence when, aware that future disability was looming, he was angry and rebellious and hard to live with.

"One of my main wishes was that he'd live long enough that we could have a good relationship," Culbert said, dabbing her eyes. "And it worked out that way."

Katy Read • 612-673-4583