About Our DBS Program
DBS therapy is currently offered to patients with movement disorders that are not sufficiently controlled with medications. These conditions include Parkinson’s disease, essential tremor, dystonia and Tourette syndrome.
Our DBS team performs comprehensive evaluations to determine if someone is a good candidate for DBS. We recognize that the success of DBS surgery depends on several factors:
- Appropriate patient selection
- Proper electrode positioning in the operating room
- Proper postoperative programming to achieve the maximum benefit from DBS without causing side effects
- Reasonable expectations of outcomes following DBS treatment and education about risks
- Appropriate home and social environment to manage post-surgical care
We continually keep these factors in mind when approaching any patient considering DBS treatment.
Deep brain stimulation (DBS) has evolved as an important and established treatment for movement disorders. While DBS is not a cure for movement disorders, it can successfully treat symptoms by disrupting the abnormal patterns of brain activity that become prominent in these diseases. Using a fully implantable neurostimulation system, DBS provides a targeted, adjustable, non-destructive, and reversible means of modulating the pathological of brain circuits. Patients with Parkinson’s disease, essential tremor, dystonia, and other movement disorders such as Tourette syndrome, who do not obtain a satisfactory response from optimal medical therapy, may be considered candidates for surgical intervention.
The current data, based on the extensive experience at Baylor and abroad, provide compelling evidence that chronic, high-frequency stimulation of the ventral intermediate (VIM) nucleus of the thalamus improves essential tremor and tremor in Parkinson's disease, while stimulation of the subthalamic nucleus (STN) or the globus pallidus (GPi) improves not only tremor, but also motor slowness, rigidity, gait, and most importantly, levodopa-related motor fluctuations and dyskinesias in patients with moderately advanced Parkinson's disease.
Deep Brain Stimulation is currently being used in selected centers around the world, including the Baylor Medicine, to treat a variety of movement disorders. In collaboration with Baylor Medicine Neurosurgery we have implanted over 500 DBS devices. Patients interested in being evaluated to determine whether they are candidates for Deep Brain Stimulation should contact our center.
Benefits and Limitations of Surgery
For Parkinson’s Disease
In patients with Parkinson's disease (PD), surgery is generally recommended at a time when medications cannot adequately control symptoms. Patients are most often referred for deep brain stimulation (DBS) surgery when they have experienced problems with dyskinesias (excessive involuntary movements that occur as a consequence of PD medications) and fluctuations (the beneficial effects of medications do not last long enough between doses). When there are limited further adjustments that can be made with medications because of these problems, surgery may be a way to limit complications from medications and to improve motor function. It is important to note that for most symptoms, surgery will NOT work any better than medications ever did. The major benefits of DBS surgery in this case are to decrease "off" time and to reduce or eliminate dyskinesias. In consequence, many patients report that their quality of life improves substantially after DBS. Medications can be gradually reduced after DBS, but this is not always the case and may depend on many factors.
In PD, motor symptoms (rigidity, slowness/incoordination, speech, walking/balance problems) that do not get better with medications will generally not get better following DBS surgery. The only exception is with tremor, which can be often be effectively controlled with DBS even when it has failed to improve with medications. Additionally, DBS is NOT a cure for PD, and it does not stop the underlying progression of the disease. Some symptoms such as balance difficulties, speech problems, swallowing difficulties, and cognitive decline develop or worsen as PD progresses, and cannot be addressed with DBS adjustment. Finally, the non-motor complications of PD, such as depression, problems with thinking or memory, constipation, urinary changes, or pain, are also not likely to be markedly improved by DBS. It is absolutely imperative that patients have realistic expectations and a clear understanding about the anticipated outcomes and potential risks before consenting to the procedure.
For Essential Tremor and Dystonia
Patients with essential tremor (ET) or dystonia (including cervical dystonia or torticollis) can reasonably expect that their tremors or involuntary muscle contractions or postures can be better controlled with DBS than with medications alone. However, there may be several factors that influence how well this can be done, including individual patient characteristics, duration of disease, and distribution of symptoms. DBS surgery will not help with balance problems or other associated features such as neuropathy or hearing loss. Tremors of the head or trunk are more difficult to treat but can improve.
For Tourette Syndrome
Patients undergoing treatment for Tourette syndrome (TS) should be aware that DBS in this condition is still under investigation and there are no guarantees about the outcome. In our experience to date, tics can substantially improve, but they do not go away completely. There may also be some improvements in co-morbidities such as obsessive-compulsive disorder and attention deficit disorder. Surgery is generally reserved for severe cases in which all medical and psychological therapies have been exhausted and unsuccessful.
There are potential risks associated with any brain surgery, including infection, intracerebral bleeding, leaks of the fluid surrounding the brain (cerebrospinal fluid), strokes, headaches, seizures, weakness, sensory changes, technical problems, wound healing problems, disfiguring scars, prolonged hospitalization, and need for additional surgery. Additionally, there may be potential risks associated with receiving anesthesia. The percentage of patients who report or experience these complications is low, but may be different according to the surgeon that is performing the procedure. It is a good idea for patients to discuss individual complications rates with their neurosurgeon.
Additionally, there may be potential risks related to the programming of the DBS device, which begins a few weeks after the surgical process is complete. When making adjustments to the DBS, there may be immediate short-lived side effects such as tingling, tightening sensations, visual changes, or speech problems. Much of the time, these may be eliminated by further DBS adjustment. However, certain effects may not become apparent until hours or days after the adjustment. These may include any of the above symptoms, but also mood or behavior changes, involuntary movements, worsening of the underlying symptoms or walking and balance problems, including falls.
Patients undergoing DBS for ET, especially if the procedure is done on both sides of the brain, are particularly prone to developing problems with speech or gait/balance changes with stimulation. It is important that these problems are communicated to the neurologist if they occur so that they can be rectified as soon as possible. There may be several ways that these problems can be addressed, but it is possible that the changes required to minimize such side effects will lead to less symptom control.
Less commonly, and in the long term, there may be device complications that include loss of effect, unexpected side effects, fracture or breakage of the wiring, change of position of the electrode within the brain, or infection. Some of these problems may require removal of the device or portions of the device.
Before Surgery: Patient Selection
There is a preoperative process that all patients being considered for surgery will undergo, but this differs according to the condition being treated.
Generally, the steps in the patient selection process include:
- Discussion and initiation with your neurologist
- Preoperative assessments
- Healthcare team consensus meeting
- Follow up discussion
For Parkinson's disease
The patient and his/her neurologist will decide together when it is time to consider DBS.
All patients will undergo an "on/off" evaluation in which their PD symptoms are assessed under conditions of no medication (“off”), and again with the full/maximal effect of medications (“on”). This is done by asking the patient to come in for evaluation first thing in the morning without having taken any PD medications. The neurologist will make an assessment of symptoms and document a physical exam on video. The patient will then take his/her usual first dose of medications. Once this dose has "kicked in" another assessment of symptoms will occur with another video documentation. This is done in order to gain a better understanding of which motor symptoms improve with medications which helps guide patient expectations of outcomes after DBS, and to ensure that DBS really does have some benefit to offer an individual.
Patients are also required to undergo a neuropsychological assessment to gain a better understanding of their baseline thinking skills and psychological state. Symptoms of depression or anxiety should be appropriately addressed prior to undergoing brain surgery. The presence of cognitive problems, such as dementia, may indicate a patient who is at risk of further cognitive decline after DBS, leading to more disability. Furthermore, the presence of dementia produces practical obstacles to achieving optimal outcomes. Patients with dementia may have difficulty accurately observing and articulating their symptoms, making adjustment of DBS parameters more difficult. Neuropsychological evaluation before surgery also provides an important baseline assessment; in cases where cognitive or emotional problems occur after surgery, the testing can be repeated and compared to preoperative scores to help determine the cause of the problems. Lastly, neuropsychological testing may be used to determine a “window of opportunity” when DBS can be safely pursued given the progressive nature of some cognitive problems in PD.
For Essential tremor
Preoperative assessment of tremor severity by formal scales is usually done so that the neurologist has a baseline against which to measure the response to DBS. ET patients are also asked to undergo preoperative neuropsychological assessments for the same reasons as outlined above.
Preoperative assessments of dystonia symptoms are done for reasons similar to those in ET patients. Neuropsychological assessments may also be considered.
For Tourette syndrome
Preoperative video evaluation, tic rating scales, and neuropsychological assessments are obtained before surgery. In some cases, a psychiatric evaluation is required. These and other factors related to a patient's social or psychological state and support network are considered together in determining if DBS is appropriate.
All cases are reviewed at a consensus conference attended by the treating neurologist, neuropsychologist, and neurosurgeon, at which time recommendations are made for or against surgery, and regarding which brain location should be stimulated.
Follow Up Discussion
All patients will receive a follow-up call from their neurologist explaining whether surgery was recommended or not, and which location of stimulation was thought to be most beneficial. Patients will have an opportunity to ask further questions at this point before proceeding with actual surgical appointments.
Before Surgery: Preoperative Planning and Imaging
In the month prior to surgery, we perform an MRI to get a highly detailed picture of brain anatomy and to plan surgical trajectory. We have typically requested an anesthesiologist to provide sedation for the MRI, as it is sometimes difficult for patients to remain still for the images. However, it is your choice whether we use sedation for the MRI.
About DBS Surgery
Baylor Medicine is fortunate to have the latest surgical technologies to allow the most customized and precise DBS surgery experience. Through our affiliated hospitals, we can perform surgery using intraoperative CT, intraoperative MRI, advanced electrophysiological techniques, and frameless DBS. Below we will describe the technique for awake DBS surgery, but please speak with your neurologist and neurosurgeon about the variety of techniques possible and what is best for you.
DBS surgery is performed in two parts:
- Part 1 involves placing the lead/electrode(s) into the intended deep brain target. This stage generally involves an overnight stay in the hospital, in a non-ICU setting.
- Part 2 involves the placement of the extension wires and battery. This stage is an outpatient surgical procedure that requires one hour under general anesthesia.
Battery replacements are another surgical procedure that patients will require periodically (generally every three to five years, if a rechargeable device is not used), depending on the amount of stimulation required to treat their condition.
DBS lead placement is done in both awake and asleep patients using a stereotactic frame. In this procedure, a rigid frame, or halo, is attached to the patient’s head just before surgery after the skin on the scalp is anesthetized with a local anesthetic. A brain imaging study is obtained with this frame in place and the images are used to calculate the position of the desired brain target and to help guide instruments to that target with minimal brain trauma. The stereotactic frame is then fixed to the operating table, a patch of hair is shaved and the scalp is washed. After making the scalp completely numb, an incision is made and a small opening in the skull is created.
The lead or electrode is surgically inserted into the desired target and tested to verify optimal placement. The lead is ultimately connected to an extension wire that passes from the scalp area under the skin to the chest.
The extension wire is connected to an implantable pulse generator (IPG), a pacemaker-like device, which can deliver pulses to the target brain area. The IPG is a small metal box which contains a small battery that powers the device. The IPG is surgically implanted under the skin in the upper chest area near the collar-bone or under the skin in the lower abdomen. The IPG delivers continuous electrical pulses with a variety of parameters, modes, and polarities, through the electrodes to produce the desired effects of DBS.
A few weeks after surgery, the movement disorders specialist will use a hand-held programmer to test different electrodes and determine the settings that provide the most benefit with the least side effects. This initial programming session after DBS surgery can last around 2 hours. This guides future programming sessions, which are usually performed every 3-4 weeks for at least 2-3 more visits to determine the optimal settings for stimulation.
Patients should be aware that DBS is not a cure for the underlying disease and the IPG settings often need to be adjusted in subsequent programming sessions.
About the Device
In all cases, the patient can activate or deactivate the DBS system by using a patient-friendly controller for their DBS that is provided by the manufacturer. Patients can also be given limited controls to make minor adjustments to their DBS on their own after discussing with their neurologist.
Omnidirectional: Lead consists of 4 electrode contacts at 4 depths (1-1-1-1 configuration) that can be used individually or in combinations to achieve stimulation of the desired target.
Directional: Lead consists of 8 electrode contacts divided across 4 depths (1-3-3-1 configuration) with middle two levels allowing for control of stimulation across the horizontal plane. This may facilitate more targeted stimulation to help maximize benefits while minimizing side effects.
|Extension||An insulated wire that is passed under the skin and connects the lead to the IPG.|
|Implantable Pulse Generator (IPG)||The IPG contains a battery that generates electric signals that are delivered to the brain via electrodes.|
|IPG Battery Types||
Non-rechargeable: The typical battery life is expected to be approximately three to five years, but this may vary depending on the individual settings and hours of use per day. Replacing the IPG battery involves minor surgery but does not require replacement of DBS leads or additional brain surgery.
Rechargeable: Rechargeable batteries are expected to last about 15 years but require charging anywhere from daily to once every few weeks depending on the battery and settings used. The patient is expected to charge the battery at home by placing a wireless charger over the chest area where the battery is implanted. Recharging sessions typically last 30-60 minutes.
|DBS Device Manufacturers||Abbott, Boston Scientific and Medtronic’s DBS devices have been approved by the FDA for use in the US.|
|MRI Compatibility||All manufacturers currently produce MRI compatible systems however certain batteries and IPG locations (along with most cases utilizing a mix of equipment from different manufacturers) are not MRI compatible.|
|Additional Features||Multiple independent current control (MICC): allows further customization of stimulation across contacts (potentially further optimizing stimulation and side effects).|
|Sensing technology: Allows recording of brain activity from the DBS electrodes potentially allowing for more customized stimulation.|