Viola Thornton is the picture of an active senior citizen. The 77-year-old woman likes to take walks, knit and sew, and even do housework. But a few years ago, when she was severly afflicted by essential tremor, a movement disorder, this “snapshot” was completely different.

“I had very bad shaking on my right side–my head, my right arm and hand were all affected,” says Mrs. Thornton. “It was hard to eat, and I couldn’t cut my own food. Even worse, I couldn’t write my name.”

Mrs. Thornton first experienced essential tremor in 1960, but not consistently over the years: “Sometimes it left me, and then it would come back.” She held a job at an Atlantic City casino hotel with no signs of the condition. But after moving to Florida in the late 1980s, the tremors returned and worsened.

Mrs. Thornton came back to New Jersey, where she did her “homework” on deep brain stimulation, a treatment she had heard about from a doctor in Florida. She then went to see Dr. Michael Schulder, a board-certified neurosurgeon at University Hospital and associate professor of neurosurgery at New Jersey Medical School. The Belleville woman was found to be a good candidate for deep brain stimulation, and in July 1999, she had the procedure. “It was a serious operation, but I was willing to try anything,” recalls Mrs. Thornton. “Now I am back sewing and knitting fairly well, and even writing a bit.”

Deep brain stimulation is approved by the Food and Drug Administration to treat essential tremor, which affects about 10 million Americans, and the tremor associated with Parkinson’s disease. The tremors present differently in each condition: In essential tremor, shaking worsens when the patient tries to accomplish a task, such as picking up a cup; patients with Parkinson’s disease have a “resting” tremor.

With deep brain stimulation, a device delivers mild electrical impulses to a specific site in the brain. These impulses interfere with the abnormal brain signals that cause tremor. The device works much the way a pacemaker sends electrical signals to the heart, leading some to refer to deep brain stimulation as a “pacemaker for the brain.” It is implanted on one side of the brain to help control tremor on the opposite side of the body.

“The results of deep brain stimulation for both of these conditions are often dramatic, restoring significant function and quality to these patients’ lives,” says Dr. Schulder, “but the treatment is not a cure.”

In 1997, the FDA approved the use of deep brain stimulation of the thalamus, but specially trained doctors perform “off label” uses of this therapy to treat many different conditions.

 “Scientifically, almost every movement disorder can be treated with deep brain stimulation,” says Dr. Schulder. “It has reduced tremor in some multiple sclerosis patients, and there could be applications for people with epilepsy or chronic pain.” The neurosurgeon conducted a small study involving multiple sclerosis patients and deep brain stimulation in 1999, an area that still captures his interest. Key to using deep brain stimulation in MS patients, he says, is selecting appropriate candidates–primarily, those with good strength and general health.

Researchers are actively seeking other possible applications of this treatment in other areas of the brain. Stimulating the subthalamic nucleus, for example, could relieve the rigidity that some Parkinson’s disease patients experience.

Implanting the system

Deep brain stimulation therapy is delivered through a small device surgically implanted in the brain.  The device consists of an insulated wire tipped with electrodes, a pulse generator and an extension wire.  The electrodes (3) are positioned where they can stimulate the target nuclei in the thalamus – the brain's message relay center.  The pulse generator (1), which produces the electrical stimuli, is anchored near the collarbone.  And the extension wire (2), which transports the stimuli from the pulse generator to the wire lead (and in turn to the brain's thalamus) is run underneath the skin of the shoulders, neck and head.

Using a console programmer, clinicians noninvasively adjust the strength of the electrical pulses to suit the needs of the individual patient.  Patients are also given a handheld magnet that allows them to turn the system on and off as they wish.

"The patient can turn the device off before sleeping, when tremors typically subside," says Dr. Schulder.  "This lengthens the lifetime of the pulse generator battery and delays the need for battery replacement."

Deep brain stimulation is possible because of advances in functional stereotactic neurosurgery. A stereotactic frame, or “halo” attached to the patient’s head enables the surgeon to more precisely locate specific areas of the brain. The day before the surgery, MRI images are taken of the patient’s brain; the morning of the surgery, a series of CT images are made. “Then, using computer technology, both sets of images are fused together to create a high-resolution, three-dimensional map of the pathway to the target and the target site itself in the brain,” explains Dr. Schulder.

A stereotactic frame, or “halo”.

The surgeon positions the lead.

After preliminary placement of the lead, a test stimulation is conducted in the OR to see how the patient’s tremor is affected. When the position is correct, the lead is implanted and the generator is inserted. The patient remains in the hospital for a couple of days following the surgery; possible complications include bleeding and infection. A few weeks after the surgery, the patient’s generator device is programmed. The generator’s battery needs to be replaced about every five years.

Deep brain stimulation is an alternative to thalamotomy, a procedure in which part of the thalamus is destroyed to eliminate abnormal brain activity and thus, control tremor. Unlike thalamotomy, deep brain stimulation is reversible and has minimal side effects.

Looking to the future

The potential for deep brain stimulation is only beginning to be realized. As more research is conducted and the FDA grants approval for other uses of this technique, the quality of many people’s lives could be significantly improved.

As for Mrs. Thornton, much of a “normal” lifestyle has been restored. “I never regret having the surgery done,” she says.

For more information about deep brain stimulation, or to make an appointment with Dr. Schulder, call (973) 972-2907.

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