A group of Liberal MPs have renewed their call for the federal government to fund clinical trials of the controversial vein-opening therapy for multiple sclerosis known as the Zamboni procedure.

Named after the Italian doctor who developed it, the angioplasty procedure isn't available in Canada and MS patients who want it have been travelling to the countries where it is offered and paying thousands of dollars for the treatment. Some have experienced alleviation of their symptoms and a vast improvement in their quality of life, while others have seen little or no effect.

Paolo Zamboni's idea is that multiple sclerosis may be related to a condition called chronic cerebrospinal venous insufficiency, or CCSVI, which involves blocked veins. He started using angioplasty procedures to open up narrowed neck veins in MS patients.

Those opposed to "liberation therapy" as it is also known, say it's a risky, unproven procedure that is giving false hope to desperate MS patients.

But Liberal MP Kirsty Duncan points out that other countries are doing clinical trials, credible, peer-reviewed studies have been published, and the evidence that it works is mounting.

"Clinical trials have demonstrated the safety of this procedure," she said at a news conference Monday in the foyer of the House of Commons. "It is time for Canada to act."

Duncan plans to introduce a private member's bill on clinical trials at her earliest opportunity, she said, and Liberal senator Jane Cordy plans to introduce one in the Senate.

Liberal MP Carolyn Bennett said her party is also concerned about MS patients who have had the procedure and can't get followup care from their doctors when they come back.

"We want the Government of Canada to make sure that people who have had treatments elsewhere because it's not available here, get proper treatment here," she said. "We can't have proof without clinical trials and it seems like we've been in this box of discrimination."

Too soon for clinical trials, government says

Liberal MPs have been making the demand for clinical trials for more than a year and it's a call that the federal government shows no signs of answering any time soon. The Conservatives have resisted involvement in pan-Canadian clinical trials until the results of seven major research projects on the procedure are known.

Last year the federal government said it would be premature to delve into the clinical trial stage because the theory underlying the treatment — that MS is linked to blocked veins — hasn't been proven. An expert panel was appointed by the government to monitor the progress of the seven research projects.

If the panel eventually recommends clinical trials, the government has said it would fund them.

The Liberal MPs were joined at the press conference by several Canadians with MS who had travelled to the U.S. to get the procedure.

"I have my life back," said Tim Donovan. "This treatment works."

A year and a half ago he was in a wheelchair and Donovan said his "future was looking grim." After paying $10,000 for the treatment in New York, the New Brunswick man said he regained lost motor skills and can now walk without difficulty.

He acknowledged that not everyone who has the procedure has experienced improvement and said that's why clinical trials need to be done.

"I think caution is good but we need trials, we need treatments, we need to find out if this works," he said.

"I want the doctors to come and start studying us … Don't say it doesn't work until you've done the trials and the treatment," Donovan said.