Medicine by Design: The Practice and Promise of Biomedical Engineering

CHAPTER 7. Moving into the Brain

Chapter 7 Moving into the Brain Kathleen Schuessler came to Dr.Ali Rezai in the spring of 2004.A 66-year-old widow and former computer programmer from Mountain Home,Arkansas, she had been having tremors for thirteen years. They began with her right leg bobbing rapidly up and down. The tremors then spread to her right arm and eventually to her left leg. By 2004, even her left arm had started to shake. Like all people with Parkinson’s, her symptoms arose after neurons in a portion of her brain, known as the substantia nigra, began to die off or malfunction in large numbers. The substantia nigra produces the brain chemical, or neurotransmitter, known as dopamine, which enables the body’s muscles to function in a fluid, coordinated manner. About 1.5 million Americans have Parkinson’s disease, with 60,000 new cases diagnosed annually. To varying degrees, these people experience tremors, rigidity, slowing motor ability, and balance problems. Over the years, Schuessler had tried medicines, such as levodopa, that restore dopamine to the brain. But medications only slightly eased her symptoms, and by 2004 she was desperate for relief. She had difficulty eating or holding a cup because of her quavering hands. She couldn’t enjoy two of her favorite hobbies, needlepoint and painting. Driving had become exhausting and difficult. “My energy was at a very low level,”Schuessler told me the evening before her surgery at the Cleveland Clinic. “My feet hurt from being
78 MEDICINE BY DESIGN in motion all the time. I had leg cramps. I used to get up early to do work because the twitches—I call them twitches—weren’t so bad. But now, as soon as I start moving around, they start. I can’t hold a phone in my right hand anymore. And just driving 5 miles to the store is annoying and even hazardous. I never know when my legs might start cramping. “I’ve had it up to here. I said to my son that I was not going to live like this, that I was not going to take it anymore. I told him I didn’t want to wind up in his cellar shaking apart.What else can I do? I can’t stand being like this. I’m losing my independence.” To date, the most effective treatment for Parkinson’s has proved to be deep brain stimulation, and the Cleveland Clinic’s Center for Neurological Restoration, led by Rezai, is a leader in the United States for DBS treatment of movement disorders. All the technologies employed in a DBS operation—the electrodes used to administer the stimulation, the imaging employed to map the patient’s brain, and the electrical apparatus that reads the firing of the brain’s neurons— are the result of advancements in biomedical engineering. As Schuessler and I talked, she sat on the edge of her bed in a robe, her right leg pumping up and down so badly that the bed shook. Her right arm quaked rhythmically in her lap. She was more than ready for her surgery. When I arrived in the surgical suite around 10 a.m. the next day, Schuessler was on the operating table, her right arm and both legs shaking. She was sedated but conscious, as she would be through most of the operation. Her skull was fixed into place by an 18-inch, semicircular stereotaxic device that would guide the electrodes to the proper region of her brain. Before the surgery, physicians had taken detailed magnetic resonance and computerized tomography images, which would give Rezai a meticulous, three-dimensional picture of Schuessler’s brain. Rezai—a trim, dark-haired 39-year-old with the abundant selfconfidence common to neurosurgeons—in 1997 became the first American surgeon to perform the DBS operation for movement disorders. After an anesthesiologist gave Schuessler a fast-acting and short-lived anesthetic, a surgical resident picked up a high-speed drill and cored out a dime-sized hole on the right side of Schuessler’s shaved head. Using the calibrations on the stereotaxic halo, the resident and Rezai lined up a narrow cannula through which the surgical team would slide the titanium- and iridium-tipped electrode—fourhundredths of an inch thin—into Schuessler’s brain. The man in charge of inserting the electrode was Dr. Benjamin L. Walter, a neurologist , who, by turning a wheel attached to a control...