The Extracranial-Intracranial Bypass — Two Decades of Faith a 1,377-Patient Trial Demolished in 1985

On October 30, 1967, in Zurich, the neurosurgeon M. Gazi Yaşargil sutured a scalp artery to a cortical branch of the middle cerebral artery under the operating microscope, rerouting blood around a blocked vessel to feed a starving brain; the operation was elegant, technically dazzling, and — for the prevention of stroke in patients with carotid and middle-cerebral disease — almost entirely unproven, and that gap between surgical beauty and clinical benefit is the entire case. For nearly two decades the extracranial-intracranial (EC-IC) arterial bypass spread on the strength of its own plausibility and on case series reporting open grafts, until a single randomized trial showed it prevented nothing it claimed to prevent.

The operation was never a fraud and never a mass killer in the lobotomy sense. It killed and disabled quietly, at the margins: a procedure with a roughly 12 percent thirty-day rate of stroke or death imposed up front on patients who, the trial would show, were no better protected afterward. The surrogate that sustained it was graft patency — the bypass stayed open in about 96 percent of cases, a number surgeons and angiograms could see and celebrate. A patent vessel looked like a prevented stroke. It was not the same thing, and conflating the two is the mechanism that kept the operation alive.

The reckoning arrived not from a regulator or a court but from an eight-year, NIH-funded randomized controlled trial led by the Canadian neurologist Henry J. M. Barnett of London, Ontario. Published in the New England Journal of Medicine on November 7, 1985, the International EC/IC Bypass Study randomized 1,377 patients at 71 centers in 14 countries and found that surgery added to best medical care did not reduce fatal or nonfatal stroke; two subgroups — patients with severe middle-cerebral stenosis and those with persisting symptoms after carotid occlusion — actually fared worse with the operation. Within a few years the procedure collapsed from a flourishing subspecialty to a narrow, rarely-indicated salvage technique. It was not banned. It was disconfirmed, and it became one of medicine’s foundational lessons in why a trial must precede an operation, not follow it.