Patient Selection for DBS Surgery
There is a preoperative process that all patients being considered for surgery should go through, but this differs according to the condition being treated.
Patients and their neurologist will decide together when it is time to consider DBS, but it is most often considered when complications of PD treatment become problematic. These complications include motor fluctuations (feeling that the medications are lasting for a short period of time before the effects wear off) and dyskinesias (involuntary movements most often related to having a high level of medications in the body). Another reason for DBS in PD relates to tremor that is not well controlled despite multiple medications.
There is a "window of opportunity" for DBS treatment, and it is important to understand where you fall within that window when considering surgery. The window tends to close if there are symptoms present that no longer respond well to medications, or advanced symptoms such as cognitive or emotional problems are present.
You may want to talk to your doctor about DBS treatment if you are experiencing the following problems:
- Medications kicking in and wearing off several times per day
- Involuntary movements that occur after taking a dose of medications
- Tremor that is not completely controlled by medicines
All patients will undergo an "on/off" evaluation in which their PD symptoms are assessed under conditions of no medication, and again with the full/maximal effect of medications. 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 then will ask the patient to take their usual first dose of medications. Once this dose has "kicked in" another assessment of symptoms will occur. This is done in order to gain a better understanding of which motor symptoms do or don't improve with medications, to help 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 before undergoing brain surgery. The presence of cognitive problems, depending on their severity, may indicate a patient who is at risk of further decline after DBS. The results of these preoperative tests will help determine which part of the brain is the safest to stimulate to control symptoms. 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.
Essential Tremor and Dystonia
Preoperative assessment of symptom severity by formal scales is usually done so that the neurologist has a baseline against which to measure the response to DBS. A preoperative neuropsychological assessment is made for the same reasons as in PD patients.
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.
Finally, 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. All patients will receive a follow-up call from their neurologist explaining whether surgery is recommended or not, and which location of stimulation is thought to be most beneficial. Patients will have an opportunity to ask further questions at this point before proceeding with actual surgical appointments.
Patients interested in being evaluated to determine whether they are candidates for DBS or other treatments, should contact the Parkinson's Disease Center and Movement Disorders Clinic, Baylor College of Medicine, Department of Neurology at (713) 798-2273.
If you or one of your family members are interested in more information about DBS, please email us at firstname.lastname@example.org, with "DBS" in the subject line.