January 2005 Archives

At Play on a Field of Trash

Hastily converted landfills can be unruly dragons, belching garbage, gas, and fire. But done right, a dump can be a thing of beauty.

Copyright Jessica Snyder Sachs (first published in Discover)

During his 12 years at Englewood Golf Course in Colorado, superintendent David Lee has seen some goofy things pop out of the ground--wigs, bowling balls, even car bumpers. The course sits on a curvaceous mound of trash some 40 feet deep, and in some places, all that separates the velvety green from the garbage is a few inches of sod. Two years ago, at another converted landfill--Charlotte, North Carolina's Renaissance Park--a soccer mom went after a stray ball that disappeared into a hole at the base of a light pole. To see in the shadows, she pulled out a pocket lighter, igniting a methane fireball that blew her several feet through the air. Fortunately, she suffered little more than minor burns.

The city of Charlotte has since posted "no smoking" "no open flame" signs at all of its several converted-landfill parks. But the waste that lies just inches below the Renaissance landfill cover continues to make itself known in other tangible ways.

On an afternoon after a gentle rain, the ground at the park's 18-hole golf course crackles like the sound of Rice Krispies. The noise comes from large patches of mud bubbling with gas. "It looks like polenta boiling on the stove," observes retired course superintendent Robert Orazi. But it smells like rotten eggs. Last year, Orazi gave up after six years of coaxing the grass and trees to grow on two feet of soil baked dry from the heat of rotting garbage below.

The course is also plagued by uneven settlement that dimples the fairways, tilts putting greens, breaks irrigation pipes, and turns cart paths into rolling "whoop-de-doos" only a dirt biker would love. Then there's the Blob, a foot-tall lump of wiggly amber-colored ooze creeping out of the fourth fairway. "We tried shoveling it; we tried covering it. It just comes back," says Orazi. Tests show "it" to be a kind of alga that feeds on the iron-rich liquid that seeps up from below. And pop-up waste? Among the scariest finds, says Orazi, are blood bags and syringes. More typical are the tires and rubber hoses that literally float up through the soil.

The hazards don't end with belches of garbage and gas. The heat of decaying trash can itself ignite the gases a landfill releases. That may have been the case when a six-foot flame shot from a crack near Renaissance's sixth green in 1989. Workers quickly doused it. But such landfill fires can spread underground for miles.

Several years ago, in Mountain View, California, an open-air amphitheater built over a landfill erupted in smoke during a Grateful Dead concert. The landfill was equipped with a gas extraction system, but the city had turned over the system's maintenance to the production company that ran the concert. When the production crew saw the smoke coming out of a crack in the ground, they cranked up the suction. The smoke disappeared, but the suction drew the fire underground and fueled it. Luckily, engineers arrived before anyone was hurt.

Closed structures, of course, are particularly susceptible to landfill gas. Without proper sealing and venting, methane can seep inside a building on or near a landfill and rise to explosive levels. That's what happened two years ago in a snack bar under construction on a landfill driving range in North Hempstead, New York. One night the water heater kicked on, igniting a fireball that knocked down the walls.

Despite the scare stories, over the past 20 years hundreds of municipalities and landfill operators have fashioned closed landfills into golf courses, parks, ball fields, playgrounds, even ski slopes. There is no national tally--largely because dumps, especially closed dumps, are considered local domain. And there is little regulation. "You don't need an EPA permit to play ball on a landfill," says Allen Geswein, of the Environmental Protection Agency's office of solid waste. "And given the current political climate, I wouldn't expect any moves in that direction."

Yet the need for more and bigger dumps won't go away. The United States generates some 209 million tons of municipal waste each year, over four pounds per person per day. Although no one knows exactly how many landfills reach capacity each year, the number is probably well over a hundred, and these monuments to waste cost money to maintain. Since 1993, for example, EPA regulations have required landfill operators to prevent their sites from leaking gas or polluted water for at least 30 years after they're closed (by then, according to theory, most of the gases from the decomposing garbage will have been released). The associated maintenance costs can reach hundreds of thousands of dollars an acre, which makes conversion to a revenue-generating facility like a golf course attractive-- but problematic.

In 1993 the EPA also set some minimum standards for the design and operation of new landfills. Though aimed at reducing off-site pollution, these rules have the side effect of improving safety and stability on top of landfills as well. They require operators to screen waste for obvious chemical hazards and to refuse medical or toxic waste. Bulk liquids--such as sewage--are acceptable only if they have been solidified with soil or other stabilizers. Operators must also cover each day's garbage with a six-inch layer of dirt, which reduces the blowing away of trash and odors. The landfill's final cap, in turn, must consist of at least two feet of compacted soil.

But only last year did the EPA make a move to control some of the gases that bubble to the surface of closed landfills. These gases are produced by the microbial food chain in the anaerobic, or oxygenless, environs of a landfill. Some bacteria, for example, degrade cellulose into sugar. Others eat the sugar, producing the acid that feeds gas-releasing bacteria. The result of their feast is a mix of methane (50 percent), carbon dioxide (40 percent), and nitrogen (9 percent), plus the trace contaminants that produce the foul smell of decay. None of these gases are particularly hazardous when allowed to dissipate in open air, says Martha Smith of the EPA's office of air quality planning and standards. It's the remaining 1 percent that includes some scary stuff.

When bacteria degrade household cleaning products, solvents, paints, and pesticides, they generate vapors that include such nasty carcinogens as benzene, toluene, vinyl chloride, and a half dozen others. Vinyl chloride is a particularly toxic and persistent gas--persistent because it kills the very microbes able to dechlorinate and so detoxify it. The EPA's new rules require landfill owners to monitor and control these dangerous vapors in the air just above the landfill cover, keeping them within a safety margin of 500 parts per million. Control measures usually include an underground venting system that sucks toxic vapors and other landfill gases aboveground and burns them off.

Unfortunately, EPA regulations apply only to large landfills-- typically those serving more than 100,000 households--that have been opened or modified since 1991. "This isn't to say that smaller and older landfills aren't of concern," says Smith. The EPA encourages individual states to set higher standards. California, for one, actually does, she adds. Moreover, whether from civic-mindedness or fear of liability, some of the nation's garbage giants are pioneering new designs for landfills and landfill parks that far exceed government standards.

The 188-acre live Oak Landfill and Recycling Center on Atlanta's outskirts is a far cry from the haphazard dumps of the past.

Roughly the size of several football fields, it is one of the Southeast's largest landfills--handling some eight tons a minute, 4,500 tons a day. Opened in 1986 by Waste Management--which is the world's largest waste-disposal company, with some 140 landfills--Live Oak will reach capacity in 2001. After that it may begin a new life as a recreational facility with soccer fields and horseback-riding trails.

Last December trash compactors at the Live Oak site were still spreading refuse on top of two of the three trash heaps that will end up 160 feet high. The first two mounds sit astride a central pit, where the operation's next phase will begin. Garbage will ultimately fill this pit, then start piling up and out like an inverted mountain against the sides of its sister peaks. The result will be a single flattened pyramid with a playable tabletop some five acres in size.

At the bottom of the still-empty central pit are seven layers of protective barriers for gathering and removing leachate--the polluted liquid from the decaying waste. The uppermost layer is a two-foot blanket of glistening white sand; not ordinary sand but grains manufactured to a specific size. If the grain sizes varied, they would pack together under the weight of the landfill, and smaller grains would fill in the holes between larger ones, preventing the runoff of leachate. Buried within this permeable, carefully milled sand is a horizontal pipe that will carry the leachate to a low-lying area. From there it will be pumped out of the landfill for disposal.

Directly beneath this layer of sand is a thin--.06 inch--sheet of high-density polyethylene (HDPE) plastic. Below the plastic lies a quarter- inch geosynthetic clay liner consisting of two fabric layers filled with a dry granular clay called bentonite. When wetted by, say, a leak in the overlying plastic sheet, the bentonite swells to form a tight, highly impermeable barrier.

The next layer down is the landfill's drainage system--a thick screen of heavy HDPE perforated pipes. Should any leachate reach this grid, it will drain to a low-lying pit. Leachate filling the pit will lift a float, which sounds an alarm signifying that the primary liner system has been breached. Live Oak operators can then draw the leachate out of the pit by applying suction. An added safeguard is a bottom layer of high-density polyethylene, which in turn lies on top of six inches of compacted clay.

Above these protective barriers, daily operations begin. Unlike the casually heaped dumps of the past, Live Oak conserves space by squeezing every last bit of air out of the garbage, creating a tightly compressed landfill structure. The garbage is sorted and distributed by size and compressibility, then ironed flat by 100,000-pound trash compactors that grind along on broad, cleated rollers. The compacting continues in two-foot layers until some 1,400 to 1,700 pounds of waste have been compressed into every cubic yard of space. Uncompacted, the same cubic yard would hold just 500 pounds.

At day's end, an eight-to-ten-foot stack of smashed waste is covered with dirt and crushed once more into a "cell." Imagining the landfill in cross section, the daily cells form continuous rows called lifts, which in turn become the landfill's horizontal tissues.

Trash compactors grade the landfill's outer slopes to a 30 to 33 degree angle to maximize the structure's stability. The continuous grading and compacting will greatly reduce the settling of garbage after the landfill is closed. More important, the compaction helps ensure that settlement is smooth and even. Though Live Oak Landfill may eventually settle by a dozen or so feet over the next 30 years, the overall shape and surface contours should remain roughly the same.

At five acres, Live Oak's upper surface is too small to be converted into a golf course, but had that been the plan, bulldozers would have shaped the top layer of refuse into berms, curving fairways, and flattened greens. For the more modest plan of a ball field or equestrian center, the landfill's upper surface will be graded into a broad, gentle crown with just enough grade, about 5 degrees, to quickly slake off rain.

Before capping the landfill, Live Oak operators will install vertical pipes down through some 140 feet of trash to collect methane-rich gas. Other landfill operators have fashioned even more detailed gas collection systems, including a grid of flexible horizontal perforated pipes that snake through the trash, absorbing gas and feeding it to the vertical gas collection pipes.

Although the EPA requires only that the gas vented from a landfill be flared, Waste Management is considering another plan for Live Oak. The gas might be drawn off to an on-site power plant and used to generate electricity. In this speculative scenario, the company estimates that for some five to ten years after closure, Live Oak could generate .8 to 2.4 megawatts of power, enough continuous energy to serve perhaps 1,200 to 3,600 homes.

The crowning touch, of course, will be the landfill's cap, the crucial barrier between its waste and park visitors of the future. At Live Oak, plans call for a composite cover combining natural and synthetic liners. The layer that lies directly above the waste will be an 18-inch layer of compacted clay. Workers will iron the clay with 60,000-pound drum rollers until it's virtually impermeable to water.

Above this layer they will install a synthetic membrane like the plastic that lines the bottom of the landfill. High-density polyethylene is a popular landfill liner because it consists of strings of polyethylene molecules (CH2-CH2) thousands of carbon atoms long. The extreme length and stability of polyethylene's carbon backbone allows the molecules to pack tightly together like a crystal and so resist the assault of corrosive landfill leachate. However, this extreme density comes at the expense of flexibility. HDPE's brittleness is not an issue at the bottom of the landfill, where the membrane lies on top of solid ground. But the landfill cover must be able to flex as the garbage beneath it decays and shifts in its bed.

A little chemical manipulation provides the answer: add hexene (C6H12) to the polyethylene. Hexene's molecular structure prevents it from folding up into the neat, crystalline structure of the polyethylene, thus creating "lumpy," disorganized patches in the polyethylene matrix. This extra elbowroom between the tightly packed carbon chains produces a more flexible, less dense polyethylene. By adding pigments and stabilizers to the polyethylene, chemists can ensure that the membrane lasts upwards of 200 years.

To prevent water from pooling onto--and possibly breaking--the landfill cover, Live Oak engineers will install a drainage net just above the surface membrane. Rainwater seeping into this open grid will flow to the landfill's edge. The drainage net, in turn, will be covered with a synthetic textile, over which will be heaped two feet of soil, seeded with grass. The entire cover system, from compacted clay to top soil, is designed to achieve an impermeability of a ten millionth of a cubic centimeter of water--a leakage rate of less than 147 gallons per acre a year.

When the landfill cover is finished, the top and bottom liners will be sealed together like a gigantic plastic bag. Post-closure maintenance, such as sealing up fractures or repairing leaks, will be costly. Although Waste Management is reluctant to confirm details concerning revenue, the cost of constructing and operating Live Oak-- including buying the land and converting it into a recreation area--will reportedly total some $400,000 an acre. That's about $75 million, and it sounds staggering until one calculates revenues for the 188-acre landfill. With tipping fees of $32 to $35 a ton, that's as much as $157,000 a day.

In reality, few landfill parks in this country are as well-financed and state-of-the-art as Live Oak. The typical scenario has been that of a cash-poor local government trying to convert an old, unregulated dump into landfill that can be used as a park. "All too often,
County engineers simply dump dirt on the landfill, plant some grass, and say here's your recreation area," says Morton Barlaz, an environmental engineer at North Carolina State University. "Without a properly engineered cover and a methane collection system, you're going to have big problems."

Stories like these strike fear in the hearts of municipal attorneys. "The idea of putting people on a landfill makes me shudder," says Ann Moore, an assistant city attorney for Chula Vista, California. As a land-use expert, Moore has followed the landfill conversion trend for many years. "It was real fashionable a while back, and now a lot of cities are experiencing big problems," she says. Adds Barlaz, "There's always the risk that local governments won't have money for the high maintenance these parks demand. When budgets get cut, parks are the first to go."

Others argue that active use may simply be incompatible with the idea of keeping landfills sealed tight within a "dry tomb" of plastic. Bill Sheehan, director of environmental biology for a landfill engineering company in Lawrenceville, Georgia, warns that even the most durable synthetic covers are likely to be punctured by plant or tree roots. The irrigation needed to keep parks green is another bugaboo. If the added water penetrates the landfill cover, it can overload leachate collection systems. This is a particular problem when irrigation pipes break under the strain of uneven settlement, as they often do.

Still, with dumps filling and open space dwindling, landfill conversions are probably here to stay. And waste disposal companies can point to several thriving examples. Take Mount Trashmore Park in Virginia Beach. Created in 1973 from a 68-foot-high, 650,000-ton garbage heap, the park is now one of the area's most popular--especially with young children, who flock to the colossal wooden playground at its base. Another success is a 600-acre resort in Industry Hills, California, home of two championship golf courses. Methane from the underlying landfill is used to heat two Olympic-size pools and a hotel laundry in the adjacent Sheraton Conference Center. Then there's Riverview Highlands, a ski and golf resort built on a 600-acre garbage mound south of Detroit.

Some communities, in fact, have apparently overcome their reluctance and are ready to embrace their trash wholeheartedly. With nearly 6 million tons of refuse already in place, Virginia Beach is now drawing up plans for another landfill-based park to keep Mount Trashmore company--one more than twice as high and 18 times as voluminous as the original. After its makeover, the landfill will be dubbed City View Park, for an obvious reason--from its crest you will be able to see all there is to see. It's the biggest thing in town.

Jessica Snyder Sachs is the author of Corpse: Nature, Forensics and the Struggle to Pinpoint Time of Death (Perseus Books) and Good Germs, Bad Germs: Health and Survival in a Bacterial World (FSG).

Risky Surgery
Last-chance surgery can mean enormous risks ... then again, it can inspire even higher hopes

By Jessica Snyder Sachs
(originally published in Longevity}

Like a shy schoolgirl, Donna Lavender curls her legs and feet together under her chair as she waits to see her doctor. This petite woman of 32 first met Jerrold Vitek, M.D., a year before. At the time, the 44-year-old Emory University neurologist advised against brain surgery. The risks far outweighed her pain and disability, he had said. And though the risks hadn't changed much since then, Lavender's pain and disability had.

The inward curl of Lavender's legs and feet is not for girlish effect; it's a symptom of dystonia, a brain disorder that causes severe and uncontrollable muscle spasms. In her case, the disease has locked her calves, ankles and feet in an excruciating, twisting cramp. "It's like a great charley horse that never ends," she explains in a rich Southern drawl.

In its various forms, dystonia affects some 300,000 people in North America alone. Its cause is not known, though there are many theories. Some dystonias start in childhood, and these may be related to gene defects. Others arise in adulthood and stem from injury. That may be the case with Lavender, who had been hit in the back and knocked unconscious by a runaway oil drum six years earlier while unloading an "18 wheeler" she and her husband had been driving. Two weeks after the accident, she lost all feeling in her legs and became bedridden. But the spunky young woman had fought back, progressing from bed to wheelchair to walker to unassisted walking. Then, six months after the accident, the dystonia began.

It came as a bad nighttime cramp in her right leg. "When I tried to get up in the morning, I couldn't stand," she remembers. "The cramping came with a burning pain like I'd never felt before." So severe was the pain that some mornings Lavender woke with her heart racing at 220 beats per minute--about three times the normal rate. Her doctors worried about heart damage. Her marriage ended in divorce. "My husband didn't want a cripple for a wife," she says, turning to hide the tears.

In 1994, Lavender married again, this time to a childhood sweetheart who had always been there for her. They settled in the small town of Millegeville, in the central hills of Georgia. But that same year, Lavender's dystonia spread to her left leg, with cramping even more painful than that in the right. An orthopedic surgeon tried to relieve the twisting of Lavender's feet by splitting and rearranging the ligaments in her anklesbut without success. So Lavender hobbled through the day on the outside edges of her curled-under feet, until the deep, burning pain would force her to lie down.

Her family doctor recommended exploring a type of brain surgery sometimes used to relieve severe case of dystonia. So she had met with Vitek at Emory. But early on in the conversation, they agreed there were too many risks involved in brain surgery including the risk of paralysis. "I knew what it was like being in a wheelchair," Lavender says. "I wasn't willing to take that chance." So she returned home to manage as best she could with bed rest and painkillers.

Unfortunately, the dystonia worsened. The spasming, which had originally come in "spells" lasting a few hours, became constant. Even worse, it began to spread to Lavender's thighs. She came to rely on narcotics to dull the pain. But the drugs dulled her mind as well, and made her depressed. She worried about the emotional toll she must be taking on her 12-year-old daughter and her new husband. The decision no longer seemed so clear cut.

"In my heart, I knew I had to [have the surgery]," Lavender tells a reporter on the day when she and her doctor are to meet to reassess their original decision. For his part, Vitek wants to make sure she understood the difficulties and risks involved, and had the resolve to face them out.

DAY OF DECISION
Despite her pain, Lavender flashes a broad smile when this man, who offers "one last hope," bounds into the room. A wiry, dark-haired researcher with an eager grin, Vitek is a pioneer in the mapping of the thalamus, a knob of gray matter the size of a walnut buried deep inside the brain. One of its functions is to serve as a relay station for movement and sensory messages traveling from the body to the cerebral cortex. The root of Lavender's dystonia may lie here, he explains, making a quick sketch.

In structure, a portion of the thalamus is like an onion, with each successive layer associated with a different body part: foot, leg, arm, shoulder, face, etc.

"At one time this are was your friend," Vitek says, pointing to the area associated with the leg. "But something has gone wrong; the cells there are now firing erratically, jamming other brain circuits and causing problems."

The "last hope" Vitek offers is a thalamotomy, an operation in which the problematic part of Lavender's thalamus would be lesionedburned away with an electrode. Thalamotomies had been performed in the 1970s, he explains, but the results were inconsistent. About half the patients with dystonia got some benefit, with a small subset getting full relief. But others came away from the surgery with weak or paralyzed limbs, slurred speech and thinking problems.

And Vitek thinks he knows why. He leans forward now, his hands spread, his eyebrows jumping in excitement. "In part, it may be that some surgeons were missing their mark," he says. The thalamus may be shaped differently in each person, and it's easy to get lost. Lesion the wrong area and ...

But Vitek has high hopes of improving thalamotomy's accuracy. He has spent five years studying the organization and cell-activity patterns of the normal thalamus in animal models. Building on this familiarity, he uses microelectrodes to probe the patient's thalamus and create a customized "map." Then, once he has isolated the problematic area, he steps aside, allowing a neurosurgeon to destroy it.

"So far we've had good results," he tells Lavender. "but we're on a learning curve." Should Lavender go through with the operation, she would be part of a study Vitek is conducting involving microelectrode-guided thalamotomies for 10 to 12 dystonia patients.

To make the decision thornier, Lavender's case will be especially difficult. The layer of the thalamus associated with the legs lies against a brain capsule filled with nerve fibers that control movement. So the surgery must be superbly precise--destroying as much of the leg-associated thalamus area as possible, without harming the adjacent fibers and possibly causing paralysis.

Vitek proposes that the team lesion only the leg area of Lavender's right thalamus. This should relieve the more painful dystonia in her left leg. And if the operation proves successful, they can later perform an operation to lesion the leg area of the left thalamus, relieving the right leg dystonia.

Despite all the risks and caveats, Donna is determined. "I know that even if this surgery doesn't help me, what you learn will help someone else in the future," she says. It's the answer that every medical researcher wants to hear. But Vitek needs to be sure. "It's going to be a tough day," he says.

While the "standard" thalamotomy can be done in as little as an hour or two, guiding it by microelectrode mapping can take the better part of a day. "And you'll have to stay awake throughout, telling me what you feel as I stimulate different areas.
"We'll have to move your leg," he continues, gently lifting Lavender's knee a fraction of an inch. She blanches with the pain, and he apologizes. "We'll try to give you medication to decrease the pain to a tolerable level, but if we sedate you too much, the cells will change their pattern of [electrical] activity, and we won't be able to map accurately." Lavender nods and smiles, and asks how much of her hair will need to be shaved. Vitek assures her that only a patch will be involved, and the surgery is set for the following Wednesday.

As she leaves the room, Vitek worries about Lavender's ability to cooperate during the operation. "She's a brave woman," he says. "But I have a feeling that pain's going to be a problem."

At home, Donna alternates between peaceful resolve and frightened doubt. But her decision is reinforced by her husband and a concerned circle of friends from the local church, who have educated themselves about Lavender's dystonia and the proposed surgery.

DAY OF DETERMINATION
Wednesday morning, 2 A.M. Lavender and her husband prepare for the drive to Atlanta. They are joined by their pastor and his wife. Together they pray, riding down the highway into dawn.

6 A.M. Lavender arrives at Emory University Hospital and is fitted with a "halo," a metal ring riveted to her skull with sharp posts. Technologists make a series of CT scans of her brain.

10 A.M. Lavender is wheeled into the operating room. The nurses cover her body with balloonlike "quilt" filled with a gentle flow of warm air. The rest of the room is kept at a chilly 63 degrees to minimize the risk of infection once Lavender's brain is exposed.

Enter neurosurgeon Roy Bakay, M.D., a no-nonsense bear of a man who takes complete command of the operating room. He positions Lavender's head in a second, calibrated ring, carefully matching its position to readings from the CT scans. "Scrub up," he directs Vitek and his neurology team. If all goes smoothly, they'll be finished in four or five hours.

11 A.M. Smooth is not to be. As Bakay attempts to inject a local anesthetic into Lavender's scalp, she jumps and writhes in pain, twisting her head inside the metal frame. "It hurts," she cries. "Hold still!" Bakay yells. Two nurses jump to restrain her. "Donna, you have to hold still," they plead. Lavender, groggy from painkillers and a sleepless night, moans with fright and discomfort.

Noon. Bakay has cut a triangle-shaped opening in Lavender's skull. Through it he has lowered the long, thin microelectrode that Vitek now uses to send and receive electrical pulses through Lavender's brain. The room fills with the amplified crackle and buzz of brain-cell activity. Green lines jump and wiggle across two monitors on a seven-foot-tall tower of electronic equipment. "Fiber at 52.5," reports Vitek to a team of assistants, who plot his readings on tables and graphs.

Vitek watches the green lines dance across the monitor, then closes his eyes to concentrate on the distinctive sound of each click, crackle and buzz. Drawing in his years of study, he lets the sounds guide him. "An injury here, not classic thalamus," he reports.
He brushes his hands softly across Lavender's left leg. He lifts it and shakes it, creating a storm of activity across the monitors. He sends a small current through the electrode and quizzes, "Donna, can you feel this?" A long pause, then a quiet murmur. "No."

2 P.M. After nearly two hours of mapping the neurology team confers in the corner of he operating room, trying to fit their graph of Lavender's brain-cell activity over an anatomical map of a "typical" brain. Angling their color-coded points this way and that, they try to make a fit that will reveal their exact location. They step back in puzzlement.

Vitek and Bakay confer. Lavender's writhing at the start of the surgery may have changed the position of her head in the surgeon's frame. Instead of hitting the thalamus, the electrode may be dead-center in the motor capsule. If so, lesioning here would prove disastrous. Hands on hips, Bakay shakes his head in frustration, then strides to the head of the operating table. He must expand the hold in Lavender's skull to move the electrode farther back in her brain. Lavender cries quietly as Bakay drills. Nurses hold her hands and whisper reassurances.

2:30 P.M. The team starts remapping from scratch. "Hear it? Hear it?" On the electrode's third pass through Lavender's brain, Vitek can hear the distinctive sound of thalamic cell activity. "This could be hip related," he says, rolling Lavender's leg to produce a burst of static. "I don't think we're quite there yet, but ..."

Bakay paces in the background. A nurse clutches a hot water bottle and drapes a blanket over her shoulders to ward off the operating room chill.

"There's the great toe; there's the ankle; there's the deep ankle," Vitek calls over several bursts of static. The mapping continues.

3:40 P.M. From the operating table, a weak, hoarse voice: "I want to stop."

Nearly six hours after being wheeled into the operating room, Lavender begs to move, to go home. Vitek stops, stunned, then steps close. "Donna, I know it hurts. I know you're tired. But we're close." He touches her left hand reassuringly. "I can't," she groans. Vitek steps back, confers with Bakay and returns. "Donna, we can give you something to help you relax," he says. "Let's just try."

4:15 P.M. The increased sedation has quieted the patient, but she lapses unresponsive. "Donna, do you feel this? Do you feel this?" Vitek asks, increasing the intensity of the stimulation to her brain. No answer.

4:50 P.M. The mapping continues, based more on electrical readings than on Lavender's feedback. But the crackle and buzz of brain activity is heard less often. Lavender's thalamus, like the rest of her, is flagging under the sedation. A small mercy: Lavender's leg and foot have visibly relaxed, uncurling for the first time in months. "We often see that during surgery," says Vitek. "But it won't last unless we lesion."

5 P.M. The nursing shift changes for the night. Vitek has yet to sit down.

6:15 P.M. The neurology team has pinpointed the "motor outflow tract" associated with Lavender's left leg. The mapping becomes more detailed, with Vitek stimulating Lavender's brain with smaller and smaller micro-voltages. "Can you feel this? Where do you feel this?" Lavender struggles to murmur her answer. "My my my ... foot."

7 P.M. The neurology team is confident they have found the area to be destroyed. But they advise against a large lesion: too risky, given Lavender's sedated responses. One more pass with the microelectrode to make sure of their bearings.

7:45 P.M. Lavender has been on the table more than nine hours. But now cooperation is absolutely crucial. Bakay begins to burn away brain tissue with a strong current through the electrode. Vitek grasps Lavender's hand and leans close. "Donna, this is it. I need to have you with me!" He asks her to smile broadly, purse her lips, stick out her tongue. Her responses tell him that no unwanted damage is occurring. "Now say the days of the week out loud. Come on, louder. Can you feel my cold fingers on your leg? Good, you can do it. Just five more minutes ..."

8 P.M. Bakay retracts the electrode. "Sedate her!" he calls, and the anesthesiologist puts Lavender into a mercifully deep sleep. The neurology staff stumbles out of the operating room. Bakay and his assisting surgeon cover the hold in Lavender's skull with a plastic plate.

Outside the surgical suite, the neurology team is cautious, but still hopeful. "A little disappointing," Vitek admits. "We'd hoped to be more aggressive [in destroying the problematic areas of the thalamus]. But the last thing we wanted to do is leave her with more problems."

DAYS OF WAITING
Some good news comes within a day. An MRI scan on Lavender's brain shows that the lesion is well placed. Recovering in her room, Lavender spends the morning moving her left leg and foot for the pure enjoyment of it. "I've got my leg back," she says.
But she hasn't forgotten the operating table. "It was so hard," she groans. "It hurt!"

Both Lavender and Vitek are cautious about considering further operations, either to enlarge the lesion if the dystonia in the left leg returns, or to restore the right leg if it doesn't. But as it turns out, a second surgery may not be necessary.

Seven weeks after surgery, Lavendar has recovered function and gained pain relief not only in her left leg and foot, but in the right ones as well. "I've got my life back!" she rejoices, as she makes plans to go to nursing school. "It was worth it."

Vitek can only guess at the reason for such a miraculous recovery on the right side. One possibility: Some neural "cross projections" from the right thalamus (affecting the left side of the body) had crossed into the left thalamus, where the team burned away cells. So the surgery may have ended up destroying the brain cells affecting both legs.

Alternatively, the pain and cramping Donna had been experiencing before the surgery may have been so severe as to produce a sort of negative feedback loop. The elimination of pain and cramping on one side may have been sufficient to break the feedback circuit and provide overall relief.

From past experience, surgeons and neurologists say that if the relief persists for three months after surgery, it's likely to be permanent. At press time, Donna Lavender was more than halfway home.

Jessica Snyder Sachs is the author of GOOD GERMS, BAD GERMS: Health & Survival in a Bacterial World (Hill & Wang/FSG October 2007).