Using balloons to enlarge veins so that more blood flows out of the brain and spinal cord fails to help multiple sclerosis patients, according to a clinical trial in Italy.

Researchers said the procedure did not improve their functioning or reduce their brain lesions — areas where toxic protein build-ups have killed nerve cells. The procedure, known as venous percutaneous transluminal angioplasty, was safe, however, the team said.

The study involved relapsing-remitting multiple sclerosis patients with a condition called chronic cerebrospinal venous insufficiency. The narrowed veins that mark that condition limit blood flow from the brain and spinal cord back to the heart.

Researchers published their study in the journal JAMA Neurology. The title is “Efficacy and Safety of Extracranial Vein Angioplasty in Multiple Sclerosis A Randomized Clinical Trial.”

Angioplasty involves doctors inserting a catheter with a balloon on its end into a blood vessel, then inflating the balloon to enlarge the vein and restore normal blood flow.