Highways & Byways

Artery disease is mysterious and confronts the physician with grave difficulties, no matter where it occurs in the body. But when nature, for safety's sake, packaged the brain and its delicate, complex system of blood circulation inside a bone box, it made things especially tough for doctors. At last week's annual Clinical Congress of the American College of Surgeons in San Francisco, the nation's leading medical researchers agreed that the chief obstacle to effective surgery on cranial arteries is one of man's quaint anatomical features--the Circle of Willis (see diagram).

The four ascending arteries (two carotid, two vertebral) that carry blood toward the brain from the aorta's arch, just above the heart, are subject to the same types of disease as other major arteries, and they should, insisted Houston's famed surgeon Michael DeBakey (TIME, June 22, 1959), be treated the same way. If the disease is true hardening of the middle layer of the artery walls, surgery can do nothing about it. If the disease is atherosclerosis (not hardening, but clogging with fatty material), affecting only a short stretch of the ascending carotid or vertebral arteries, the knife can be used with high hopes of success.*

Dangerous Location. But in the Circle of Willis (named for English Anatomist Thomas Willis, who described it in 1664), surgery is tricky. Into the circle, like highways converging into a cloverleaf, the four ascending arteries pour the brain's blood supply, and from the circle branch off the principal feeder lines from which oxygen is extracted for the brain's ceaseless activity. Located inside the skull about the eye-and-ear level, the Circle of Willis is in too dangerous a place for surgeons to cut into its vessels. Yet the different segments of the circle's perimeter are subject to all the ills that afflict the ascending arteries --and more.

Besides fatty obstructions, reported Tulane University's Dr. Homer D. Kirgis in San Francisco, the Circle of Willis can also be afflicted by a kind of malign predestination. Some people are candidates for certain types of strokes as a result of what happened--or didn't happen--before they were born. The human fetus goes through a phase in which the internal carotid artery on each side feeds into three branch arteries and supplies most of the blood to its hemisphere of the brain.

Before birth these vessels are supposed to rearrange their connections so that the internal carotid supplies only two main branches. But, said Dr. Kirgis, about 14% of all brains studied at autopsy show the internal carotid still feeding three branch arteries on one side of the brain, and in a few cases this is true on both sides. A hemorrhage or, more common, a clot in the internal carotid of such people is apt to do far more damage than in people of normal arterial development, because there is a greater bottleneck for blood supply to essential areas.

Plastic Skin. About 4% of accidents in brain arteries are episodes of bleeding from an aneurysm--a ballooned-out, weak section of an artery. Aneurysms are usually congenital in origin. When they grow large or rupture, they may cause serious brain damage or death. The mortality rate in untreated cases is about 50%.

The vast majority of all aneurysms occur in the Circle of Willis. To get around the risk of irreparable damage involved in cutting into the circle and to protect the aneurysm patient from further attacks of increasing severity, Tufts University's Dr. Bertram Selverstone has devised a daring and ingenious technique. First, Dr. Selverstone opens the way to the Circle of Willis by taking out a big flap of bone from the skull. (An arteriogram--an X ray of the brain's blood vessels involving the injection of radio-opaque dye into the patient--will have already spotted the site of the aneurysm.) Then, using an artist's airbrush, Selverstone sprays the aneurysm with a mixture of plastics that combine to form a coating similar to Saran Wrap. This is tough, but too thin to give full protection against further leakage or bursting. So he sprays on a second layer, of epoxy plastic. The result: enclosure of the aneurysm in a capsule far tougher than the natural artery wall.

*The four basic techniques for clearing local arterial roadblocks: 1) cut out the diseased section, pull the severed ends of the artery together and stitch them: 2) make a slit in the side of the artery, insert a special instrument, ream out the fatty debris and close the incision with a couple of stitches; 3) slit the artery lengthwise along the blocked stretch and put a long oval plastic patch in the wall to increase its diameter; 4) make an artificial detour for the blood by splicing a length of plastic tube into the artery, above and below the blocked section.

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