Medicine: Ultrasound Surgery

Two men in their late 403 left Iowa City’s University Hospital last week and boarded planes to carry them to their homes in the South. Each walked with a fast, short-stepped gait (“festination”) and had a marked tremor on his left side. These were symptoms of advanced Parkinsonism, a disorder (cause unknown) of nerve nuclei at the base of the brain. But each man had just been freed of such symptoms on the right side. For the first time, after more than five years of helplessness, each could write legibly and feed himself an in-flight meal. This improvement in a disease bafflingly difficult to treat had been wrought by three “buzzes” (actually inaudible), lasting less than two seconds each, of ultra-high-frequency sound waves.

Ultrasound, as the practitioners of a new and arcane art call it, refers to vibrations above the limit of human hearing (about 20,000 cycles per second*) In industry ultrasound waves are used to precipitate carbon and sulphur from chimney exhausts, abating the smoke nuisance and recapturing useful materials, and for testing big metal components such as locomotive axles for flaws. In dentistry there is the ultrasonic drill. In medicine a few enthusiasts have reported good results with ultrasound in arthritis, neuritis, muscle spasm and athletic injuries. It will break up gallstones or kidney stones in an animal’s body, and some physicians hope soon to use it for this in human patients.

Sharper Than a Knife. Nobody knows how ultrasound achieves most of its effects. But its use in neurology at Iowa City has a solid base in years of painstaking research. Physicist William Justin Fry, 39, worked with underwater sound for the Navy during World War II, went to the University of Illinois at Urbana and carried on ultrasound work with funds from the Office of Naval Research. In the early postwar years most ultrasound generators produced only a crude, unfocused beam. Fry built a two-story laboratory with equipment reminiscent of science-fiction illustrations, gradually refined his complex apparatus so that he could focus powerful ultrasound beams from four separate irradiators onto a target about the size of a pinhead.

By this time Fry was ready to join forces with the State University of Iowa’s Neurosurgeon Russell Meyers, who had long been convinced that the way to treat Parkinsonism was by destroying nerve bundles in two tiny parts of the brain (one on each side) called the ansa lenticularis. But he found conventional surgery too crude and damaging: it meant putting a knife through healthy tissues to get at the almost inaccessible ansa lenticularis. He saw the same objections to alcohol injections (TIME, March 21, 1955). Dr. Meyers believed that ultrasound might prove sharper and more precise than any scalpel, worked with Fry in designing and building a treatment room for Iowa City.

Holes in the Head. Three weeks ago, after innumerable experiments on animals to test accuracy, effectiveness and safety, the first human patients were wheeled in. Preparation took far longer than actual treatment. Under a local anesthetic four little dents were burred into the patient’s skull, one above each eye and two in the back of the head. On a rolling table, the patient was wheeled back so that his head was under a stereotaxic (space-positioning) instrument. A pin on a micrometer mounting fitted into each burr hole. X rays revealed the main landmarks inside the skull. They could not show the elusive ansa lenticularis but its position was determined from them. Coordinates were carefully noted.

On the day of operation, each patient got only a local anesthetic, an injection of procaine hydrochloride into the scalp. Then, with a drill and saw, Dr. Meyers removed a piece of the skull, four by five inches. Ultrasound cannot be transmitted through bone because on meeting such resistance it generates too much heat. With the skull flap out of the way, the surgeons made a shallow pan in its place, using a metal strip as border and the dura mater (the brain’s parchment-like covering) as the bottom. This they filled with salt solution from which all gas had been removed (ultrasound is transmitted best through a liquid medium).

A Quick Pose. With the patient’s head in the exact position of the day before (determined by the pins and coordinates and another X ray as a double check), the four-part head of the quartz-crystal, ultrasound irradiator was lowered into the pan. While the patient remained fully conscious, no more distressed than he would have been in a dentist’s chair, and talked occasionally, Dr. Meyers gave the ‘signal and a technician pressed a button. Ultrasound, at a frequency of 980,000 cycles per second, shot through intervening brain tissues but not in sufficient intensity to damage them. The four beams came to a sharp focus at the exact part of the ansa lenticularis on the left side (controlling right-side movements) that Dr. Meyers wanted to destroy. The ultrasound dose lasted only 1.8 seconds. The patient was moved twice, a minute fraction of an inch, so that two more pinhead-size parts of the ansa lenticularis were destroyed.

The salt pan was removed and the bone flap replaced. (It would grow back solidly into the skull in three or four weeks.) By the time the patient was wheeled back to his room, the uncontrollable tremor, the involuntary bending of the arm and turning in of the thumb on the right side had disappeared. In a few months, both patients will return to Iowa City for treatment of the ansa lenticularis on the right, to halt the Parkinsonian movements of their left sides.

*Dogs can hear tones up to 40.000 cycles (hence the “silent whistle” dog call), bats up to 100.000.

* So called because James Parkinson described it in 1817.