Your brain is the most complicated machine known, a mass of billions of interconnected neurons, each of which may form an average of about 7,000 synapses (connections with other neurons), forming your personal and highly unique connectome – the map of all of those connections. At each of these synapses, electrochemical signaling fires in patterns that may be individual or in networks, which generate a signal strong enough to detect with electrodes on the scalp. This is what allows us to study brain waves on an electroencephalogram (EEG). Brain electrical activity can also be changed in a way that helps patients with neurologic diseases, and is the basis of deep brain stimulation (DBS).
However, the story of how we got here goes back farther than most would guess. For example, in the first century A.D. the Roman physician Scribonius Largo described using the electric ray fish, torpedo, to shock the heads of headache sufferers (1). Since the common ray can deliver a charge of up to 200 volts to immobilize prey, one can imagine the effect on a person might be less than pleasant. Electric fishes were actually used in European medicine at least into the eighteenth century. There were many other experimental uses of electricity, on living and expired subjects, in centuries past. Thus it was not so unusual that in the early twentieth century electroconvulsive therapy was established in psychiatric medicine.
Work with electricity also led to a greater understanding of how our brains operate. In the 1930s, Canadian neurosurgeon Wilder Penfield famously mapped functional regions of the brains of awake patients with electrical stimulation during surgery (2). He was not alone in using electricity to study or modulate the brain. These early pioneers led the way to the formation of DBS.
DBS as we know it today begins in the early 1950s, when Spanish neuroscientist Jose Delgado reported implantation of electrodes in humans (3). A decade later he described radio-equipped electrodes which he had placed in various animals, and in 25 people. In 1963, he demonstrated he could stop a bull from charging (or at least veer off-course) with the device. Over the following decades, investigators around the world experimented with brain electrodes. Two groups in 1991 ushered in modern technology when they successfully demonstrated that DBS could treat tremor (4,5).
DBS was FDA-approved in 1997 for tremor associated with essential tremor and Parkinson disease (6). In 2002, the indications were expanded to include other symptoms of Parkinson disease. Previously, patients may have undergone surgical procedures such as thalamotomy or pallidotomy, which affected or diminished motor symptoms by surgically destroying a specific brain region. After DBS was approved, it became the preferred, or much more commonly administered, treatment. There are several reasons for this, such as the facts that DBS is not intended to destroy brain tissue, is adjustable and programmable, and is at least as equally effective as the older surgical procedures. DBS is also reversible. It may be turned off and sometimes will be removed, though this is uncommon. It has been implanted a great deal since 1997. According to the International Neuromodulation website, between 1997 and 2012 there were over 80,000 DBS implants around the world for a variety of indications (7).
Who should have DBS?
In Parkinson disease, the procedure is usually intended to treat disabling motor complications, tremor, and dystonia refractory to medical treatment. For example, patients may want DBS when dyskinesias become intolerable, or when medications fail to work in a predictable way. Some patients complain of sudden, unpredictable off time when medications should be working. DBS may help, as it is a continuous delivery system instead of the pulsatile approach of medication dosing. There are also PD patients whose tremors respond inadequately, or not at all, to medications. Typically, if other symptoms of PD such as stiffness and slowness respond to medication, then DBS may be a good option for tremor control in these patients. DBS does not cure PD, but helps to diminish some of the motor symptoms. Because of this, patients are usually able to cut back on medications, and thus, medication side effects.
And, who should not have DBS?
Medtronic, the manufacturer of the first, and still most widely used DBS platform, offers the following exclusion criteria: no longer responsive to medications; severely disabled, even in the best “on” state; medical conditions that prevent surgery; and onset of dementia. It may be hard to define exactly when a person has reached each of these states, and this is where having a team-based approach to assessing the patient can be helpful. In Maine, a team composed of a neurosurgeon, movement disorder neurologists, neuropsychologists, and specialized nurses meet to discuss potential cases and outcomes.
What are the risks?
Risks of surgery can be serious and fortunately occur in only a small minority of patients. These can include stroke, paralysis, coma, death, bleeding in the brain, cerebrospinal fluid leak, seizure, infection, allergic reaction to implanted material, confusion, pain at surgery sites, and headache. These risks should not be taken lightly and should be discussed at length with your doctor prior to making a decision to proceed. Since no two patients are the same, there may be other risks unique to that person, and sometimes the risks are too great.
Programming of DBS is meant to stop motor symptoms of PD, but may also cause unwanted side effects, such as tingling, temporary worsening of symptoms, speech problems (for example, slurred speech or trouble producing words), double vision, dizziness, weakness of the face or limbs, temporary worsening of dyskinesia, coordination problems, feelings of shocks or jolts, numbness, and very rarely, behavioral disturbance. Usually, programming changes can eliminate these issues. In the rare circumstance where relief from side effects cannot be found, DBS can be turned off.
Who has had the procedure in Maine?
Lots of people. Before 2013, patients were implanted in other states. Since 2013, dozens of implants have been done in Maine with Dr. Rughani. I asked a couple of my patients about their experience as I was writing this article.
Barbara Keezer of Augusta, Maine, told me that she had suffered with PD for over 14 years when, in 2005, the development of uncontrolled dyskinesias led to deep brain stimulation with Dr. Van Horne in Boston. She states she “could tell a difference right away, dyskinesias stopped. I couldn’t walk before the surgery because I never stopped moving. I was in a wheelchair, but after DBS I could walk by mys
elf.” Her husband Gordon notes that she had several good years. Still, with a 25 year course, the disease has progressed. In the last 2 -3 years she has needed a wheelchair again, and a lot of help from him. “She has gone downhill gradually with the Parkinson’s, you can’t change that. But, she still wants to do things, to be independent.” Barbara states her husband is always reminding her “don’t do that by yourself.” He says, “I have to watch her, and make sure she doesn’t fall.” Yet, Barbara reports that DBS is still helpful and keeps her doing what she can. “If you turn the DBS off, I can’t move at all. So, it’s doing something good.” For her it was, and still is, a definite benefit.
Forty-three year-old Melinda Jewell has young-onset PD, and in 2013 had right brain DBS in Boston. In 2015 the left brain was implanted by Dr. Rughani in Portland. She is happy with the results and tells me the local 
experience was ”really good, with a great team.” She was a little nervous about going through it a second time in a different place. At the procedure,”Dr. Rughani talked to me and I think he was distracting me a little,” she smiles. “And, the anesthesiologist was funny. He made jokes and I listened to country music. I forgot to be nervous and I am glad I did it.” As to whether or not it has been helpful, she says, “Yes! I still have some issues, but I probably wouldn’t be working now if I hadn’t had DBS.”
P
atricia Joyce has had PD since 2005, and underwent DBS surgery in 2014 with Dr. Rughani. She notes, “I didn’t think the surgery was bad at all. It was pretty cool actually. They warned me that the worst part was staying still for so long. I did get a little itchy, but other than that, it was fine. I’m happy I did it, and I’d do it again.”
Still, as Dr. Rughani notes in our interview, the risk and benefit should be taken very seriously, and carefully considered before proceeding with surgery.
1. Debru, A. The power of torpedo fish as a pathological model to the understanding of nervous transmission in antiquity. C. R. Seances Soc. Biol. Fil. 2006;329: 298–302.
2. Penfield, W., Boldrey, E. Somatic motor and sensory representation in the cerebral cortex of man as studied by electrical stimulation. Brain 1937; 60, 389–443.
3. Delgado et al. Technique of intracranial electrode implacement for recording and stimulation and its possible therapeutic value in psychotic patients. Confin. Neurol. 1952;12:315-19.
4. Benabid et al. Long-term suppression of tremor by chronic stimulation of the ventral intermediate thalamic nucleus. Lancet 1991; 337:403–406.
5. Blond, S., and Siegfrid, J. Thalamic stimulation for the treatment of tremor and other movement disorders. Acta Neurochir. 1991; S52: 109–111.
6.http://www.fda.gov/newsevents/newsroom/pressannouncements/ucm451152.htm
7. http://www.neuromodulation.com/deep-brain-stimulation
