the science that set me free
(Originally published May 2019 in Hippocampus Magazine; the version you see here has been edited slightly.)
The little boy’s parents sit nearby: a man who speaks fractured English and a woman wearing a hijab who does not speak at all. We’re together in a small waiting room with milky white walls and straight-backed chairs alternating red, blue, green; to my left is an aquarium, faintly glowing; above the secretary’s desk a US map is peppered with pushpins—many, but if it were a world map, there would be many more, to represent the thousands of families who have traveled here from every corner of the globe.
When I stand, I feel the man’s eyes on my legs, but he doesn’t watch me the way people usually do when they try to figure out why I move so stiffly. He already knows. He stares not because I am different from his son, but because I am the same.
His eyes move to my face, and a thousand unspoken words hang in the air between us. In our silence, I press my palms together. He smiles, bows his head, and his hands copy mine.
We pray to different gods, speak in different languages, and live in different countries, yet in this moment we are united by our faith in one surgeon—a surgeon whose steady hands and brilliant mind could change our lives forever.
Twenty-three years earlier, I lay in another hospital, born three months premature with lungs that collapsed whenever I took a breath. Modern medicine saved my life, but oxygen deprivation left me with diplegic cerebral palsy (CP)—damage to the area of the brain that controls my legs. Although my form of CP is pretty mild, it’s immediately clear something is different about the way I move. Walking is not my native language; I’ll never master the subtle intricacies of movement like somebody with an innate understanding of its grammar, rhythm, and cadence.
Along with my accented gait pattern, my condition gave me constant muscle spasms—spasticity—from the waist down. This vicious cycle begins with the sensory nerves in the spinal cord, which initiate a reflex telling muscles to tighten. Typically, the brain replies with an opposing message—Relax!—but when its motor pathways have been injured, that memo never arrives, and unrelenting stiffness sets in.
Spasticity has gripped me for as long as I can remember, and as a young child, I assumed it was a universal fact of human existence, as indisputable and ever-present as green grass and blue skies and homework on Mondays. I still remember the day this assumption shattered. I was eight years old, playing a game of tag and laughing as I skidded across the yard, my shoulders tingling from the shadow of my friend’s fingertips as she reached for me. Pressing forward, I willed myself to move faster, faster, but with each step, my feet stumbled and my muscles seized and my knees twisted inward. As my legs collapsed and I tumbled to the ground, my mind was consumed by this riddle, consumed by a body that seemed to defy the laws of physics. That night, I asked a question born from equal parts frustration and curiosity: “Why do I move slow when I try to move fast?” My mother, for all her wisdom, had no answer.
Fourteen years later, my orthopedic surgeon explained my paradox to the young-faced intern beside him. “Spasticity is velocity-dependent,” he said. Simply put, fast movements send spasticity into overdrive and eventually, these constant spasms cause joint breakdown and permanent muscle tightening. Many people with CP who walk without assistance as children lose that ability as adults. In fact, at this appointment, my surgeon looked me in the eye and said it was “truly remarkable” that I was still walking independently. His words were a warning disguised as a compliment; he couldn’t tell me when I would lose this ability. I wish I could say it was courage that brought me a thousand miles to the neurosurgery waiting room of St. Louis Children’s Hospital, but it was something closer to fear.
On one of the walls of that waiting room, directly across from the little boy and his parents, is a collage of smiling children labeled “Faces of Hope” with a purple-lettered subtitle: “Dr. Park—thank you for giving hope and a future to so many.” Beside the collage hangs another frame, a 2002 Time Magazine article stating that Dr. TS Park hoped to perform 1,000 more surgeries before retiring. Fifteen years and 3,000 surgeries later, his retirement plans are non-existent.
After the little boy finishes his appointment, my mother and I are summoned to another small room, this one with blue-gray carpet and yellow, photo-covered walls. Dr. Park enters deferentially, as if he were a guest in his own office. He has a reputation as a man of few words, but when he begins speaking, I realize he’s simply a man who saves his words for important thoughts.
At one point, he flexes my ankle quickly, then releases. His exclamation, tinted with a Korean accent, is triumphant. “See? Do you see? That’s spasticity!”
I follow his eyes to a tremor on the top of my foot, and, at first, I’m struck by an urge to laugh—I’ve never seen anybody so delighted by evidence of brain damage. But then he glances up at me, a smile playing on his lips.
“Your improvements will not be mild, not be moderate,” he says. “They will be significant.” My mother starts to cry, and all at once I understand. He finds his joy not in the symptom but in his ability to fix it.
The surgery he performs—selective dorsal rhizotomy, or SDR—involves cutting the overactive sensory nerves in the spinal cord, and it’s the only treatment that can permanently eliminate spasticity. Although dorsal rhizotomies have been widely performed on humans since the 1980s, the first beneficiaries (if you can call them that) were brain-damaged cats. Their surgeon was Sir Charles Scott Sherrington, a man who leaves me with decidedly mixed feelings.
“Freakishly brilliant” would be an understatement: Sherrington coined the term “synapse” to describe the point where messages are passed between brain cells, and he won a Nobel Prize for his extensive contributions to the field of neuroscience. But I’m inclined to think he might have been freakish in other ways too, because he was the kind of person who wrote metaphors about rainbows and then spent his spare time decerebrating cats. (That’s science-speak for “removing most of their brains while they are still alive.”) After decerebration, the cats developed spasticity, so he opened their spinal cords, cut their sensory nerves, and watched as their muscles relaxed again.
That was 1898. Seven years later, when the first rhizotomies were done on humans, they didn’t go well. A German neurosurgeon eliminated spasticity in 159 patients, but he destroyed so many nerves that they suffered from severe, permanent, coordination-impairing numbness. Pegged as a disaster, the dorsal rhizotomy was abandoned for more than six decades until a French surgeon stumbled upon an incredible discovery: he could get rid of spasticity while preserving sensation by only cutting a fraction of the abnormal nerves. Then, in 1978, a doctor in Italy decided that cutting indiscriminately wasn’t such a good idea. He began monitoring the nerves’ electrical activities during surgery to determine which fraction to target, and dorsal rhizotomies became truly “selective.” And my surgeon, Dr. Park, further refined the procedure in the early 1990s by pioneering a less invasive technique called single-level SDR. While earlier surgeons removed many pieces of bone from the spine, his method requires removing only one.
But even in the twenty-first century, SDR has risks. Some centers throughout the world still perform the multi-level approach, which can lead to chronic back pain and spinal deformities. The accidental destruction of motor nerves can cause paralysis or incontinence. Dr. Park’s side effect rates remain impressively low: none of his patients have experienced either of these outcomes. However, some have reported other side effects. All SDR patients—children and adults alike—have numbness for the first few weeks, but adults often end up with some permanent decrease in sensation. Those in their forties also run the risk of developing chronic nerve pain, and it usually takes them longer to build post-op strength and neural pathways compared to younger patients. (At the time of this writing, because of these additional challenges, Dr. Park doesn’t perform the procedure on anybody over age fifty. **2024 update: Dr. Park retired in June 2024.**) Fortunately, any numbness is typically only a minor annoyance, and long-term nerve pain is rare. For many people—including myself—the prospect of living without spasticity far outweighs the potential side effects.
On the morning of my surgery, I am sprawled face-up on a bed, a large Sharpie “X” on my back marking the scalpel’s path to my spinal cord. The pre-op nurse hovers over me, wearing her nervousness like an accessory to her scrubs. She goes to great lengths to avoid eye contact, and she dances around references to needles as if speaking of them is akin to letting out a string of profanities.
Four needle-pricks and three nurses later, an exceptionally talented anesthesiologist finally manages to place an IV in my wrist. To Nervous Nurse’s credit, I am a notoriously hard stick—my veins are so pathetically subpar that even the anesthesiologist says she’ll have to redo it in the operating room.
“I’ll wait until you’re under, though,” she says, and then she pauses, brightens. “Oh, I wish you could be awake for this! SDRs are so cool to watch!”
Eventually, someone tells me it’s nearly time. I’m not nervous until she mentions she’s going to give me something to make me feel “out of it.”
“I don’t want to lose control,” I say.
Silence washes over the room, and I imagine they all share the same thought. (Does she know what she’s signed up for?) One of the nurses tries to reassure me. “Relax,” she says. “It’ll be just like having a couple of drinks.”
Somehow, the prospect of an inhibition-dissolving liquid coursing through my bloodstream is more daunting than major spinal cord surgery, but I don’t say anything, just hold out my arm. They inject the sedative, and before my bed reaches the hallway, I am out cold.
Cold. I open my eyes to white lights and something is beeping and my body is trembling so violently that the word I need to say is stuck in my throat. I try again, but my shaking cuts off the sound. Then a woman’s voice, far away even though she stands over me: “Yes, I know you’re cold. It’s okay. You’re okay. It’s just your body reacting to the medicine.” I’m not sure how much time passes before the next voice: “Can you wiggle your toes for me?” The voice is making sure I am not paralyzed. I am glad it does not ask me to move my legs. My legs feel heavy, disconnected, as if they are no longer part of me. Silently, I tell my toes to move. For the first time in my life, they do not resist me.
In my next memory, I am awake in my hospital room, unable to sleep because the breathing monitor attached to my chest triggers constant, trilling alarms. Instead, I run my hands over my legs. I can’t really feel them yet, but they are straight . . . relaxed . . . no longer bent from the constant barrage of signals telling them to tighten—and tucked under the temporary blanket of numbness is something I’ve never sensed before: I can feel the mattress beneath the back of my knees. Tears spring to my eyes. This is a gift I hadn’t known to hope for, a quiet reminder that the fight in my legs is gone. In this moment, I wonder if the little boy’s father understands what he has given his son.
We are tethered to our beds by a maze of wires and tubes, but we are free.
~
Five days later, when I am released from the hospital, I cross paths with that family again. The man steps from the hospital lobby with his wife and son just as the hotel shuttle pulls up to the sidewalk for my mother and me. He hurries forward with outstretched hands to help me from my wheelchair, but a flood of panic surges in my chest: the shuttle has a step.
Even with support, I am wobbly. My legs still feel as though they’ve been injected with Novocain, and years of spasticity have masked my weakness by causing my muscles to fire reflexively and erratically, without proper input from my brain. Now that the spasms are gone, I must learn how to activate my muscles on my own.
The man smiles, offering his shoulder to lean on, and I smile back as I thank him, but my heart is pounding. What if I can’t do this?
And yet when I tell my leg to move, summoning the exact amount of force that would have landed me squarely on the step just one week before, my foot hovers far above its target. My brain had accounted for spasticity, compensating for signals that were no longer working against me. Moving in this body is strange—my legs feel unbelievably light now, as if the world suddenly lost half of its gravity, as if I spent my whole life wearing ten-pound weights around my ankles and somebody finally remembered to remove them.
~
SDR has given me so much: I can navigate curbs independently; my gait is smoother; I can wiggle all my toes; I can jump farther and higher than ever before, walk in a (semi-)straight line, and balance on one foot for several seconds at a time. I do have some side effects from the surgery, but they’re minor. For example, I have a little bit of numbness and a slightly dulled sense of touch in one leg.
Even more than the visually obvious milestones of my new mobility, I love being able to wake up in the morning with loose, comfortable legs. To be able to slide on a pair of jeans without my feet cramping up. To be able to venture outside on a winter’s day with muscles that don’t root me to the spot. I love being able to stretch without pain, and to have the ability to build real strength in my legs for the first time in my life. I love that I can watch horror movies with my friends, and during the scary parts, I startle for only a moment—the tightness no longer cascades through my body, staying with me for hours. After twenty-three years of knowing only tension, I can finally relax.
~
Four months after surgery, I return to St. Louis for my follow-up, and just after we finish my appointment, my brother, mother, and I rush to cross a busy intersection.
“You don’t have to run,” my brother says, and then he pauses, grins. “Actually—I take it back!”
He slips his hand into mine and together we sprint, laughing, through the streets of the city that changed my life. We have no finish line: this is my victory.
![My brother and me at the time the story takes place](https://sdrchangeslives.com/wp-content/uploads/2024/01/kerry-benson-story-photo-1024x758-1.webp)