Powerful, Precise Lasers Blazing a Trail in Medicine

When first her sight and then her life was on the line, lasers came out of the realm of science fiction for Nancy Hardesty and burned a tumor from her brain.

Until then, she had thought of lasers as high-tech toys in space-adventure movies.

“They all use laser guns, and my kids love them. I didn’t think of the laser in terms of surgery,” said Hardesty, 46, who teaches grades four and five in Hammond, Ind.

Over a four-month period last year, the vision in her left eye became blurred, then obliterated. She went to six doctors before one found a life-threatening brain tumor that could have blinded or paralyzed her.

In October, Dr. Leonard Cerullo attacked the tumor with a laser beam, now a key part of medicine’s arsenal.

For five hours, the brain surgeon guided the beam over the cottony-looking surface of the white, golf-ball-size tumor. With each passing of the beam, a layer of the tumor was disintegrated in a wisp of smoke.

Three days after Cerullo had vaporized the tumor, Hardesty tried her contact lenses.

“It was just unbelievable,” she said. “I could see again. It was like a miracle!”

In operating rooms around the world, lasers are the Space Age weapons that enable doctors like Cerullo to treat diseases that were considered incurable 25 years ago.

Some scientists look forward to even greater medical breakthroughs as byproducts of laser development work being done for President Reagan’s proposed “Star Wars” missile defense system.

It is the so-called free-electron laser that holds the most exciting potential for medical uses, doctors say.

The device can produce a wide variety of laser beams--some not yet imagined, let alone invented.

Doctors believe it might create a laser in the X-ray spectrum of light. Such a laser, in theory, might be able to attack tumor cells after it passes harmlessly through skin and bone as a standard X-ray does, said Cerullo, who is an associate professor at Northwestern University Medical School.

“It could eliminate open surgery as we know it,” he said.

The laser already has transformed several fields of medicine. In the 26 years since it was developed, it has become a standard tool in a variety of specialties.

“I don’t think the public realizes how common lasers have become,” said Dr. Leon Goldman, director of Jewish Hospital’s Laser Research Laboratory and Laser Treatment Center in Cincinnati.

Neurosurgeons use them to attack tumors growing deep in sensitive areas of the brain. Ophthalmologists use them routinely to combat glaucoma and other causes of blindness. Dermatologists can make port-wine birthmarks disappear with laser power. Lasers are used to remove hemorrhoids, and are being tested against tooth decay.

“We’re able to do things now that we simply couldn’t imagine doing 20 years ago,” said Dr. Terry Ernest, an ophthalmologist and professor at the University of Chicago School of Medicine.

The laser (acronym for light amplification by stimulated emission of radiation) was developed in 1960 by an American scientist, Theodore Maiman.

It works by stimulating the electrons orbiting the outer shells of atoms until their energy is released as light of a single color, or wavelength, in an intense beam that can be focused powerfully enough to cut metal.

In neurosurgery, the laser is used primarily as a cutting tool to remove tumors in sensitive areas of the brain. About 20% of all brain tumors are found in such locations, Cerullo said, “but in that 20%, it has made a tremendous impact.”

In an operating room at Northwestern Memorial Hospital, Cerullo pointed to a white blob on a computerized tomography (CAT) scan, which had produced a black-and-white picture of a 75-year-old woman’s brain.

The tumor, the size of a lemon and growing larger, has blinded her left eye and is doing the same to her right eye, he said. Untreated, the growth could cause permanent speech loss and paralyze her right side.

To reach the tumor, Cerullo must operate in an area of the brain where one slip with a scalpel could paralyze or blind the patient.

Before the laser, he said, neurosurgeons used forceps and other tools to cut, pull and tug a tumor free.

“The problem is that by just doing that, you might tip the balance and cause irrevocable and unacceptable damage,” Cerullo said.

Two resident doctors opened the woman’s skull. They used an electrified pair of large tweezers --called a bipolar--to lift the brain tissue and expose the tumor. As they worked, the bipolar’s buzzing and snapping sounds rose above the steady beep of the heartbeat monitor.

“Bring in the laser, please,” Cerullo said.

A white box, about the size of a television set with a 24-inch screen, was wheeled up to the operating table. It contained an invisible, carbon-dioxide laser for vaporizing the tumor and a red, helium-neon laser the surgeon used as a guide.

Cerullo peered through a $90,000 microscope that magnifies 25 times. With a curved metal instrument he pulled back the brain and exposed the tumor, an oval, white blob. The brain quivered and pulsed with each heartbeat.

Cerullo adjusted a tiny control lever to place the neon laser’s red dot over the tumor. He stepped on a floor pedal and the invisible laser was aimed through the red light.

As he directed the beam across the tumor, orange embers rippled in its path and a layer of tissue disintegrated in a wisp of gray. By moving the laser, he kept it from cutting all the way through the tumor and into the brain.

Cerullo paused. The tumor’s outer layer had been charred. Over the next four hours, he repeated the process until the tumor was gone.

“We’re removing thousands of millions of cells in seconds, by vaporizing them,” he said. “Any tumor that is in a sensitive area of the brain, I think, is a good candidate for laser. It has introduced a new level of precision and gentleness in neurosurgery.”

Not a Panacea

Cerullo uses the laser on about 40% of his patients. He sometimes achieves dramatic results, as in Hardesty’s case, but cautions that the laser is not a panacea and does not lessen the risks of brain surgery.

The operation on the older woman was a technical success. Most of the tumor was removed, but some of it remained in an area that is inaccessible even with a laser, Cerullo said.

A day later, the remaining tumor apparently choked off a blood vessel, Cerullo said, and the patient died of a massive stroke.

The laser carries its own risks, Cerullo said. It can burn the cornea and retina in the eyes of a patient, doctor or nurse if protective glasses aren’t worn. It also can burn the skin.

Used properly, however, a laser should pose no more risk than other high-tech surgical tools, Cerullo and others say.

The carbon-dioxide laser is one of eight major types used in medicine. Each type emits a different light wavelength and produces a different effect on the body and its cells. Each was developed through laboratory experiments and, through tests on animals, found to be effective in some disease-fighting tasks.

Heat Destroys Tissue

Surgeons use the carbon-dioxide laser to heat tissue, such as a tumor, until the cells actually explode, or disintegrate.

Specialists in internal medicine have found an effective tool in the neodymium:YAG laser, which works as an anti-coagulant. While cutting, the laser also stops tissue from bleeding by burning it, a feature that makes it a good tool for operating on bleeding stomach tumors.

A third type, the argon laser, enables ophthalmologists to work on the retina without harming the eye’s lens or cornea. Its wavelength is absorbed only by colored tissue, and the beam passes harmlessly through clear tissue.

The lasers’ power can be modified by:

- Adjusting the level of electricity, from one-thousandth of a watt to 100 watts.

- Varying the diameter of the beam. A pinpoint has greater impact than a less-focused light.

- Applying the laser continuously or firing it in tempering bursts, called “pulses.”

- Moving the beam. Its impact is increased by focusing on one spot.

Eye Uses Were First

Ophthalmologists were the first to cross medicine’s laser frontier when they began using lasers to weld detached retinas back into place inside the eye, said Goldman, who has worked with lasers since 1961, when he was a professor at the University of Cincinnati Medical School.

“The early thinking was that its primary use was to replace the scalpel, to do the cutting and stop the bleeding,” said Dr. Ellet Drake, a cardiologist and secretary of the American Society for Laser Medicine and Surgery.

“Then it began to catch on in areas where it did things the scalpel couldn’t do,” he said.

In ophthalmology, for instance, the laser led to new treatments for causes of blindness such as glaucoma and diabetes, said Ernest of the University of Chicago.

Diabetics sometimes develop abnormal blood vessels in the retina, a condition that threatens their vision. With the laser, ophthalmologists make multiple burns in the retinal tissue and, for reasons not entirely understood, this causes the abnormal blood vessels to disappear, Ernest said.

They also use the laser to vaporize “after-cataracts,” translucent membranes that sometimes grow on the eye after cataract surgery.

Rids Eye of Membrane

“It’s really very exciting,” Ernest said. “The patient comes in with maybe 50% of their vision, and within a minute, the laser explodes the membrane and the person can see fully again.”

The laser does increase the cost of some procedures. Most hospitals and clinics add a surcharge for use of a laser, but cost varies with the procedure.

At the same time, Cerullo and Drake say that in some fields, the laser actually reduces costs because patients recover more quickly and spend less time in the hospital. Some procedures, such as several in ophthalmology, are now done outside the hospital.

Cerullo and Goldman predict that lasers will play an even greater role outside surgery, in diagnostic testing and in treating afflictions such as heart disease and cancer without incisions.

Already, Goldman said, doctors are experimenting to see if lasers can be used to remove blockages or clots in coronary arteries, a major cause of heart attacks. The procedure would involve slipping a thin, laser fiber-optic tube into the vein or artery, where the laser would vaporize the obstruction.

Cerullo believes this procedure will be perfected eventually as an outpatient treatment, so that the need for heart bypass surgery will be greatly reduced.

Some patients already are benefiting from experiments with new lasers.

Maria Gamboa, for example, had a large, maroon birthmark--the type known as port-wine stain--over the upper left side of her chest and neck.

“I was always self-conscious,” said Gamboa, a financial analyst with a Chicago bank. “I always wore turtlenecks and makeup.”

Today, the birthmark is gone, disintegrated by a laser being tested at Northwestern University Medical School by Dr. Jerome Garden, assistant professor of dermatology.

“I’d been trying to find someone to treat me since high school, about 10 years ago,” Gamboa said. “Right now, when I look at the pictures from before, I can’t even believe it.”

Dermatologists believe port-wine stains are congenital, caused by defective blood vessels that become engorged with blood and give the skin a purplish hue, Garden said.

The argon laser has been used to remove such birthmarks, he said, but its power and wavelength sometimes produced scarring.

Three years ago, Garden began experimenting with a yellow dye laser, which he said can work without scarring.

The dye laser’s yellow light doesn’t immediately affect normal blood vessels, but is absorbed in large amounts by the defective ones because they are larger, Garden said. The light heats up the defective vessels until they break apart and disintegrate, he said.

During one last treatment, Garden did what he called a “touch-up” on Gamboa. Her results, he said, are typical of more than 100 patients he has treated.

The patient, wearing colored glasses to protect her eyes, rested in a reclining examining chair. Garden pointed a silver, hand-held laser tube at her chest.

It emitted split-second bursts of blinding, orangish-yellow light, and each pulse destroyed some of the few remaining discolored blood vessels.

Each zap of the laser felt like a pinprick to Gamboa. In 15 minutes, her upper chest and neck were speckled with tiny bruises.

“You get an instantaneous black-and-blue, but it goes away within five to 10 days,” Garden said. “Once that goes away, there is a slow process, over six to eight weeks, where there is a gradual lightening of the skin.”

Doctors predict even greater medical advances will come out of development of the “Star Wars” laser weapons that President Reagan envisions as an anti-missile shield in space and on the ground.

One of the main components of the system is the “free-electron laser,” which doctors believe holds the greatest medical potential.

It was patented in 1974 and the first model was working in 1977, but the device didn’t catch on immediately because of its unwieldy size and multimillion-dollar price tag.

Today, there are about a dozen free-electron lasers in use in laboratories, and more are being built for the missile defense system.

“The FEL is a fabulous laser,” Goldman said.

Scientists say the free-electron laser can be used to produce a spectrum of wavelengths and laser beams--from ultraviolet light to microwaves.

Each laser produced by the device could become an effective tool against ailments ranging from cancer to personality disorders, Cerullo said.

The federal government has allocated $40 million at six universities to explore the free-electron laser’s medical potential.

Cerullo, who directs the research at Northwestern, said that officials hope to have an FEL built and operating there in about two years.