A successful new technology for treating symptoms of Parkinson’s disease, essential tremor, dystonia (involuntary jerking or twisting movements) and possibly other movement disorders, is gaining more widespread use at Strong Memorial Hospital and nationwide.
The device, called a deep brain stimulator, is implanted in the patient and controls neural activity in specific sites of the brain by using adjustable electrical pulses.
About five million Americans have essential tremor, an inherited disease that develops in a person’s 30s or 40s, impairing basic motor skills. 1.5 million suffer from Parkinson’s disease.
The stimulator was approved by the Food and Drug Administration four years ago for use on the thalamic region on one side of the brain. In January of this year, the approval was expanded to include both sides and the subthalamic nucleus and globus pallidus interna regions, structures that help control motor functions. This will allow a wider range of options for combating movement problems.
“Neuromodulation may be the key to treating a number of disorders,” said Dr. Robert Bakos, chief of neurosurgery at Strong and associate professor of neurosurgery at UR. “There’s a whole spectrum of movement disorders, not just Parkinson’s. There are other areas to pursue, other targets and a whole vast network of possibilities. Now there’s some possibilities for application of the deep brain implant for [treatment of] pain.”
Bakos is the neurosurgeon on a team of three doctors who perform the implantation procedure at Strong. The other two doctors are Timothy Counihan, whois an assistant professor of neurology at UR, and David Loiselle, a neurophysiologist and also an assistant professor at the university.
The patients must be awake during the surgery so their reactions can be monitored while the implant is put in and tested. Loiselle operates the equipment for monitoring and recording their neural activity, while Counihan works directly with the patients to gauge their motor skills and condition.
Bakos, who has been working in neuroscience for 33 years, performs the actual surgery. “Before you perform the surgery on a patient who’s awake, a bridge of trust has to be established,” he said.
Bakos and Counihan spend time with patients before the surgery and work closely with them during follow-up visits to monitor their progress and adjust the stimulator.
The implanted device itself consists of leads, each tipped with four electrodes, that are inserted into a specific area of the patient’s brain. The location of insertion is determined by CAT and MRI scans prior to the operation. The leads run under the skin to a pacemaker, which is implanted under the collarbone and generates the electrical pulses. It is capable of being reprogrammed with a magnet-like device, allowing doctors to fine-tune the electrical pulses. The patient can also shut off the device with another magnet. The power source of the device lasts three to five years, depending on usage.
Because of risks inherent in surgery, especially for elderly patients, the deep brain stimulator is only for patients for whom other treatment options failed.
For many Parkinson’s sufferers, increasing medication causes intolerable side effects, while decreasing it brings back the symptoms they are trying to avoid. “They’re damned if they do, damned if they don’t,” said Bakos. This device offers hope for those to whom medication is becoming less effective.
“The real advantage of this procedure is, essentially, reversibility,” Counihan said. “With pallidotomies [another treatment for movement disorders], once you burn a hole, it’s there, there’s no going back. We’re replacing medication with electricity, which allows us the ability to change the dosage.”
Disadvantages
The procedure is not free from defects, but for the patients that undergo it, “the benefits of it far outweigh the disadvantages,” Counihan said. “They reach the end of the line for medical options.”
Two serious dangers of the operation are brain hemorrhage and seizure, but their risk is small?seven out of 280 patients in clinical trials. Other more likely risks include device-related infection, bleeding into the brain and lead wires wearing through the skin. However, if necessary, the device can be removed without leaving permanent damage.
The FDA’s analysis of a clinical study by Medtronic Inc., the implant’s manufacturer, claimed that almost all patients had some sort of adverse effects after the procedure. Bakos and Counihan answered that the FDA exaggerated some of the figures, and that their criteria for adverse effects were too strict. For example, patients reported feeling a buzz when the device was turned on, which went away shortly afterwards. The FDA reported the buzz as an adverse effect, although it was not harmful and actually beneficial since it let the patients know the device was working.
Balancing the risks of the operation and possible benefits is a delicate task, but Bakos does not delude the patient. “It has to be made clear to the patient that this is an invasive procedure. It’s part of their decision process.
“The funny thing is, these people are told [about these risks], but their problem is a progressive disease, where the medication will no longer work, so for them the balance is shifted towards surgery,” he said.
“Many people weren’t even able to bring a glass of water to their mouth for years, so it’s quite emotional that they’re finally able to do that after the procedure,” says Bakos.
He recounted one exceptional story of a patient in her 50s with essential tremor whose condition was so bad that she wasn’t able to perform basic functions like eating and writing. But seven months after the procedure, having shown remarkable improvement, she was engaged to be married. The procedure made her able to have a life again, after not being able to leave the house for 15 years.
So far, Bakos has performed 12 of these operations in the Rochester area, and there are about 30 patients on Strong’s waiting list. According to the implant’s manufacturer, approximately 3,500 patients underwent the procedure nationwide. In the next two to three weeks, Bakos and Counihan will carry out the newly approved procedure on the subthalamic nucleus region of the brain. They expect to perform such procedures on a weekly basis.
Uzilov can be reached at auzilov@campustimes.org.
