A second Canadian has died after having an experimental vein treatment for multiple sclerosis, CBC News has learned.

Maralyn Clarke, 56, of Calgary, suffered from MS for years before travelling to a clinic in Orange County, Calif., on April 13 to have her neck veins opened. The treatment is based on Italian Dr. Paolo Zamboni's theory that the treatment relieves symptoms of MS.

Clarke's husband said she had been hoping the procedure would give her a better life and relieve some of her symptoms.

Hours after she was discharged from the clinic, her husband said she started having an extreme headache, nausea and vomiting and was taken by ambulance to a nearby hospital.

According to Clarke's medical records, the final diagnosis included "irreversible brain injury." She was taken off life support on April 18.

The vein procedure has risks whether it is done for MS or other diseases, said Dr. Michael Brant-Zawadzki, a neurointerventional radiologist and a clinical professor of radiology at Stanford University in California.

Intervening in the veins draining the brain can cause stroke in two ways, Brant-Zawadzki explained.

"There's a risk if a tear occurs inside the skull that there would be a stroke," he said. "There's a risk of a clot occurring that could either rob the brain of sufficient blood flow or a clot migrating to the lungs causing a pulmonary embolus."

Dr. Michael Brant-Zawadski refuses to do the procedure that people with MS are clamouring for. CBC

Brant-Zawadzki refuses to do the procedure even though people with MS are clamouring for it.

"I do think that physicians themselves believe they're helping these patients, but unconsciously there's an enablement going on of what could become self-harmful, if not a truly self-destructive process."

Doctors at Synergy Health Concepts Inc., where Clarke had the procedure, declined to comment, citing patient confidentiality.

The clinic's consent form for the therapy includes stroke and death in its list of possible complications.

Dr. Barry Rubin, the head of vascular surgery at Toronto's University Health Network, is part of the Canadian government's panel that recommended a safety trial into the treatment last month.

Rubin is in contact with a physician in California.

"I subsequently phoned the physician in California and he confirmed that one patient died shortly after the procedure and a second patient had a stroke," Rubin said. "The severity of that stroke is unknown to me."

The husband of another woman with MS said he still believes in the therapy.

Caroline McNeill of Langley, B.C., travelled to California to have her neck veins treated with balloon angioplasty in March and plans to return for another treatment.

"It was hard for me to see my wife go to bed on a sunny day when the kids are playing in the yard," Geoff McNeill recalled. McNeill said he now has his wife and mother of his children back, to go dancing on their tenth anniversary.

"I still believe in the therapy, and I still believe this is the right thing to do given what we experienced with Caroline's procedure so far," he said after learning of Clarke's death.

Clarke's husband, Frank Lamb, wouldn't speak on camera but told CBC News what happened and shared her medical records. He said he now wishes she had never had the procedure, and believes if she hadn't she would still be alive.

The first Canadian to die following the vein procedure was Mahir Mostic, 35, of St. Catharines, Ont. Mostic died on Oct. 19, 2010, one day after doctors in Costa Rica tried to dissolve a blood-clot complication that formed around a metal stent used to prop open a vein in his neck.

Rubin agrees all invasive procedures carry the risk of complications. Since no one knows how many people with MS are having the balloon procedure on their veins, he said it's impossible to accurately assess the complication rate to determine if it is acceptable. Rubin said it's more reason to conduct rigorous scientific studies on whether the procedure works and is safe.

With files from CBC's Kelly Crowe and Sophia Harris