The US Food and Drug Administration (FDA) has alerted healthcare professionals and patients about an unproved treatment for chronic cerebrospinal venous insufficiency (CCSVI), which has been linked to serious injuries and death.
CCSVI, which is characterised by a narrowing of veins in the neck and chest, has been said to cause multiple sclerosis or contribute to the progression of the disease by impairing blood drainage from the brain and upper spinal cord.
The experimental procedure, known as 'liberation therapy', uses balloon angioplasty devices or stents to widen the narrowed veins.
The FDA received reports in 2011 of a patient who died from bleeding in the brain after undergoing the treatment and another who was left permanently paralysed by a stroke.
These incidents led the agency to issue a formal warning letter to an investigator who was conducting a clinical study of the treatment without the necessary approval, in February 2012.
The sponsor / investigator voluntarily closed the study.
Other complications, including detachment and migration of the stents, damage to the treated vein, blood clots, cranial nerve damage and abdominal bleeding, have been associated with the therapy.
The FDA is notifying physicians and clinical investigators who are planning or conducting clinical trials using medical devices to treat CCSVI that they must comply with FDA regulations for investigational devices.
William Maisel, chief scientist and deputy director for science in the FDA's Center for Devices and Radiological Health said: "Because there is no reliable evidence from controlled clinical trials that this procedure is effective in treating MS, FDA encourages rigorously-conducted, properly-targeted research to evaluate the relationship between CCSVI and MS."
"Patients are encouraged to discuss the potential risks and benefits of this procedure with a neurologist or other physician who is familiar with MS and CCSVI, including the CCSVI procedures and their outcomes."