A doctor examines C.T. scans from a patient before performing deep brain stimulation surgery to alleviate tremors. Courtesy of Swedish Neuroscience Institute.

Peter West makes his living working with explosives, but for a long time he did his job despite a terrifying handicap: tremors. His hands would twitch and shake, his head would bob, his speech would become garbled. Sometimes he could barely pour milk from a pitcherthe milk slopping over the side of the glass. At that time, I was mixing high explosives, West says. I knew it was a matter of time before I dropped one.

Luckily the most significant thing West, 54, dropped was his golf ball. In 2003, while on the links, a doctor in Wests party noticed he was having trouble balancing the ball on the T. One thing led to another, and West was diagnosed with essential tremor, a neurological disorder characterized by shaking of the hands and other body parts. The main treatment option was drugs that would make him sleepya hazardous side effect in his line of work.

A stimulator and leads used for deep brain stimulation surgery. Courtesy of Medtronic.

West, however, hooked up with doctors at Rhode Island Hospital who performed deep brain stimulation. In 2004, they opened Wests skull and implanted an electrode in his thalamus, a structure in the center of the brain just above the brainstem. They ran a wire to another device, inserted under the skin of his collarbone, that generated pulses of electrical current. The treatment reduced Wests tremors to manageable levels, and allowed him to continue his work.

The underlying theory of deep brain stimulation, pioneered in the late 1980s, is that the pulses disrupt the aberrant neuronal impulses that are thought to cause tremors. We seek out these abnormal neurons and tell them to stop, says Andres Lozano, who chairs the neurosurgery department at the University of Toronto. [For more on DBS, see Sparking Recovery with Brain Pacemakers, by Morten L Kringelbach and Tipu Z. Aziz, Scientific American Mind, December 2008/January 2009.]

Drawings from a patient with a essential tremor show improvement after deep brain stimulation surgery at Swedish Neuroscience Institute. Courtesy of the Institute.

Recently deep brain stimulation has become a mainstream treatment for Parkinsons disease, a degenerative neurological condition that also leads to uncontrollable shaking, which often leaves patients disabled. Most of the 90,000 people worldwide who have had deep brain stimulation procedure suffer from Parkinsons. About five percent of the procedures are performed on patients who, like West, suffer from essential tremor, estimates Lozano.

The FDA has approved the procedure for both essential tremor and Parkinsons, and its practiced at a number of academic centers, including the University of Toronto and the Swedish Neuroscience Institute in Seattle. Surgeons at Swedish treat about 40 patients with tremor every year. Lozano says his team operates on about 10 with essential tremor as well as more than 100 with Parkinsons. As surgeons develop more experience with the operation, however, they are starting to apply it to psychiatric conditions, such as depression and obsessive-compulsive disorder.

On Friday, December 16 at 9am Pacific Time, 12pm Eastern, Scientific American streamed video of an operation performed an hour earlier in the day on an essential tremor patient, courtesy of Swedish Neuroscience Institute in Seattle (watch it now in the viewer below).

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Soup With A Spoon

Follow up studies have shown that 90 percent of essential tremor patients see improvement after surgery. Typically, the benefit is significant: a 90 percent reduction in hand tremor, as measured on a severity scale of 1 to 4. Quality of life improves as well. Patients become newly able to perform ordinary tasks such as drinking water without spilling, dressing themselves and brushing their teeth.

To calm essential tremor using deep brain stimulation, surgeons implant electrodes into the brain's thalamus. Courtesy of Swedish Neuroscience Institute.

Along with the benefits, however, come significant risks. To find that thalamus, surgeons have to dig deep inside the brain. The chance of bleeding or stroke is about 1 percent, Lozano says. In 5 to 8 percent of patients, complications from a broken electrode or an infection ensue. In about 20 percent of cases, Lozano adds, the electrical stimulation can cause speech and balance difficulties, tingling, pain and occasionally mood changes. Because of such risks, Lozano wont operate unless a person is disabled and medications dont work for them. In some cases, hell accept a patient whose tremor interferes with her career even if it is not otherwise debilitatinghes operated on several surgeons, for instance.

West falls in that category. For him, the disease was troublesome but not life threatening. For as long as he can remember, his hands have twitched and shook. At age five or six, his arms would be resting on a table only to suddenly jump several inches to a new location. He struggled with sports as a teenager. When hed throw a ball, a twitch or tremor would send it off in the wrong direction. Since his dad and his sisters also had tremors, West thought it was a normal condition.

After his diagnosis, Wests tremors continued to worsen. On average, tremor gets more severe at a rate of 1.5 to 5 percent per year, according to Elan Louis, a neurologist at Columbia University who has studied the disorder. Doctors offered to prescribe medications to diminish the shaking. Anti-seizure and high-blood pressure drugs are the first-line treatments for essential tremor, although these drugs only work for about half of patients. West didnt give them a chance, however, because of what he did for a living. Which is better? Making explosives with tremor or sleepy? he asks. He spoke to me from a quarry, where he was on a project to break up bedrock for use under roads. So he lived with the tremors, until he found out about the brain surgery.

patient drawing

A patient performs a drawing test for tremor during deep brain stimulation surgery. Courtesy of Swedish Neuroscience Institute.

West recalls the operation vividly (he was awake during the procedure). At one point the surgeon wanted to test the electrode placementboth for its effects on the tremor and on other brain systems such as vision. He asked West to look over at the door to the operating room and to tell him if the top of its frame was straightparallel to the floor. It wasnt, West recalls. It was V-shaped. A few adjustments to the electrode straightened out that door.

West has had some side effects from the surgery. He thinks he gets more irritable and agitated than he used to--at least on some days. He has decided to live with that problem, because his tremor is virtually gone. Some tasks, such as painting a baseboard or holding a glass with one hand, are still difficult. But he can pour milk now, eat soup with a spoon and manipulate chopsticks. He enjoys working with explosives, which he feared he would have to give up if his tremors hadnt calmed down.

Last Saturday, December 10, he was building a train for his granddaughter. The project required soldering, hooking up electrical wires using a soldering gun, a task that once took him more than two hours to accomplish. But this time, he said, it was no problem.


Postscript: For more on deep brain stimulation for essential tremor as well as other types of surgery for the condition, please see tomorrows webcast on this page. Peter West is happy to talk to other people with essential tremor considering getting the operation. He can be reached at pwwest@maine.rr.com.