Deep brain stimulation (DBS) has emerged as a potential option for select Tourette syndrome (TS) patients whose motor and/or vocal tics significantly impact the quality of life despite maximal use of other treatment options. The media buzz surrounding DBS for TS has been exciting; however, it has created many questions for patients and their families to consider. In this update we aim to address the most commonly asked questions and also we aim to update the current state of DBS for TS.
What is deep brain stimulation?
What is deep brain stimulation?
DBS is a relatively new procedure that utilizes an implantable electrode to alter the activity of brain circuitry. The procedure is FDA approved for Parkinson’s disease, essential tremor, dystonia and OCD, and currently utilized for patients who have not responded to standard medical or behavioral therapy, and who have no cognitive difficulties or “minimal” cognitive (thinking issues) dysfunction may be appropriate candidates.
There are two essential components to the hardware involved in DBS the implantable electrodes and the programmable pulse generator. The DBS electrode is implanted into a specific target within the brain and the pulse generator, or neurostimulator, is implanted under the skin just below the collar bone (or in the abdomen for women); an extension cable passes under the skin and connects the electrode to the neurostimulator. The DBS electrode has four contact points, the sites through which electricity is delivered. Active contacts can be selected by computer and multiple settings can be adjusted for individual patient needs.
The settings can be adjusted for different pulse widths (how long each pulse of stimulation lasts), frequencies (how many pulses are delivered each second), and amplitudes of stimulation (how much voltage is delivered).
Why would DBS help to in Tourette Syndrome?
There are two essential components to the hardware involved in DBS the implantable electrodes and the programmable pulse generator. The DBS electrode is implanted into a specific target within the brain and the pulse generator, or neurostimulator, is implanted under the skin just below the collar bone (or in the abdomen for women); an extension cable passes under the skin and connects the electrode to the neurostimulator. The DBS electrode has four contact points, the sites through which electricity is delivered. Active contacts can be selected by computer and multiple settings can be adjusted for individual patient needs.
The settings can be adjusted for different pulse widths (how long each pulse of stimulation lasts), frequencies (how many pulses are delivered each second), and amplitudes of stimulation (how much voltage is delivered).
Why would DBS help to in Tourette Syndrome?
DBS has the potential to “neuromodulate” abnormal communication that occur deep within the brains of people with TS. So far researchers have probed into several areas in the brain of people with TS (the centromedian thalamus, the internal globus pallidus, the external globus pallidus, and the anterior limb of the internal capsule) and they have had mixed success. The best target for “neuromodulation” has yet to be determined, however it does appear that DBS has positive results in some patients.
What does it mean to have a multidisciplinary/interdisciplinary screening prior to DBS and why is it important?
An important concept to understand when evaluating any potential DBS candidate is that successful surgery usually requires a multi/interdisciplinary approach. For TS a neurologist, psychiatrist or general practitioner can serve an important role in identifying and in triaging potential DBS candidates. However, prior to surgery, potential candidates should be comprehensively evaluated by an experienced team.
The goal of the evaluation is to make sure that the candidat is optimally suited for DBS and can fully participate in the various operative and post-operative procedures. These teams should optimally include a psychiatrist experienced in TS, a neurologist experienced in TS, a neurosurgeon experience in DBS, and a neuropsychologist. In some cases social work, physical, occupational and a speech therapy may be useful. Additionally, adequate imaging must be performed (usually a MRI and/or CT), and the results of each part of the screening should be discussed in a DBS team meeting/board.
The results of this team meeting should be shared with the patient and the family to be sure expectations may be reasonably addressed by the overall decision on the recommended approach to therapy.
The goal of the evaluation is to make sure that the candidat is optimally suited for DBS and can fully participate in the various operative and post-operative procedures. These teams should optimally include a psychiatrist experienced in TS, a neurologist experienced in TS, a neurosurgeon experience in DBS, and a neuropsychologist. In some cases social work, physical, occupational and a speech therapy may be useful. Additionally, adequate imaging must be performed (usually a MRI and/or CT), and the results of each part of the screening should be discussed in a DBS team meeting/board.
The results of this team meeting should be shared with the patient and the family to be sure expectations may be reasonably addressed by the overall decision on the recommended approach to therapy.
Who is a good candidate for DBS?
Probably the most crucial step for successful DBS is careful patient selection. Careful consideration of patient characteristics will directly impact outcome. Despite the widespread use of DBS, there are no standardized criteria for selection of candidates. The TSA has recently published recommendations for DBS surgery in the journal Movement Disorders. Below are some general considerations for patients and families.
• The diagnosis of Tourette syndrome must be made by an expert psychiatrist and/or neurologist.
• The Yale Global Tic Severity Scale should be performed and must reveal incapacitation with severe distress, self-injurious behavior, and/or quality of life disruption. OCD, Depression, and ADHD are not exclusionary provided tics are the major difficulty requiring surgical intervention.
• Age must be >25 by FDA guidelines and TSA guidelines and many studies may exclude Tourette patients younger than this age. There may be exceptional cases where younger patients are acceptable candidates for DBS surgery.
• The patient’s TS symptoms must have failed to response to conventional therapy for tics. To meet these criteria, subjects must have been treated by a psychiatrist or neurologist experienced in Tourette syndrome (usually treated with at least three different pharmacological classes: an alpha-adrenergic agonist, dopamine antagonists (typical and atypical), and a benzodiazepine).
• Patients must have received stable and optimized treatment of comorbid or other medical, neurological, and psychiatric disorders for the previous 6 months.
• If the patient has a tic that is focal or addressable by botulinum toxin treatment this should be considered.
• If present, psychiatric disorders such as anxiety, depression, or bipolar disorder must be treated and stable.
• Patients must be screened for dementia or cognitive dysfunction that will place the patient at risk for worsening cognition (thinking), and/or may impact the ability to cooperate with tasks involved in the study.
• Patients should have been evaluated for the suitability, and implementation if suitable, of behavioral interventions to reduce tic severity.
• The Yale Global Tic Severity Scale should be performed and must reveal incapacitation with severe distress, self-injurious behavior, and/or quality of life disruption. OCD, Depression, and ADHD are not exclusionary provided tics are the major difficulty requiring surgical intervention.
• Age must be >25 by FDA guidelines and TSA guidelines and many studies may exclude Tourette patients younger than this age. There may be exceptional cases where younger patients are acceptable candidates for DBS surgery.
• The patient’s TS symptoms must have failed to response to conventional therapy for tics. To meet these criteria, subjects must have been treated by a psychiatrist or neurologist experienced in Tourette syndrome (usually treated with at least three different pharmacological classes: an alpha-adrenergic agonist, dopamine antagonists (typical and atypical), and a benzodiazepine).
• Patients must have received stable and optimized treatment of comorbid or other medical, neurological, and psychiatric disorders for the previous 6 months.
• If the patient has a tic that is focal or addressable by botulinum toxin treatment this should be considered.
• If present, psychiatric disorders such as anxiety, depression, or bipolar disorder must be treated and stable.
• Patients must be screened for dementia or cognitive dysfunction that will place the patient at risk for worsening cognition (thinking), and/or may impact the ability to cooperate with tasks involved in the study.
• Patients should have been evaluated for the suitability, and implementation if suitable, of behavioral interventions to reduce tic severity.
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