What is Deep Brain Stimulation (DBS)?

The basics of DBS

Deep Brain Stimulation (DBS) is a medical device which requires the surgical implantation of a battery-powered neurostimulator in the chest that is connected with a wire under the skin to a lead implanted deep in the brain. The neurostimulator generates continuous pulses of electricity that are delivered through the wire to the lead, where they cross into the brain through metallic contacts on the lead called electrodes. The types of pulses used (called the waveform and frequency) and the location of the lead (and so electrodes) is determined for each patient based on the on a symptomatic basis, with the help of anatomical brain scans collected by a MRI or CT, and following the advice of the medical team. There are different theories of how DBS works, but what is for certain is that the electrical pulses stimulate neurons around the electrodes, which changes brain function in a way that reduces symptoms.

DBS has shown great promise in improving the quality of life of patients including those with Parkinson’s patients by stopping the abnormal brain activity (nerve signals) that cause symptoms of disease (e.g., tremors, rigidity, bradykinesia, and postural instability).¹ The exact mechanisms by which DBS affects physiological processes remain studied, but DBS functions in some way to remove the abnormal brain activity leading to symptoms.² The National Institute of Neurological Disorders and Stroke (NINDS) currently deems DBS only available for patients who are resistant to pharmacological treatments, or exhibit severe side-effects. DBS is also being explored in depression, obsessive-compulsive disorder, tourette syndrome, and other disorders relating to motor irregularities. Other pertinent research on DBS can be found at www.clinicaltrials.gov.

Who is a candidate for DBS?

Careful patient selection is the first and perhaps the most important step for success of DBS. There are no standardized criteria for choosing candidates, and criteria may differ depending on the targeted symptom or disorder. Patients are selected very carefully before a DBS surgery is performed and the process will vary across countries and medical centers. There are different important aspects of patient selection that should be considered in PD, essential tremor, dystonia, and OCD/Tourette.

Parkinson’s Disease Candidates: There are no strict criteria in determining eligibility, but those with idiopathic Parkinson’s are preferentially chosen. For example on medical center may decide that the best Parkinson’s disease surgical candidates have idiopathic Parkinson’s (not parkinsonism which includes other diagnoses such as multiple system atrophy, progressive supranuclear palsy, Lewy body disease, corticobasal degeneration), are younger (below age 69, but may be older), with a response to medication (at least 30% improvement, but preferably higher), but still have medication refractory to symptoms (wearing off of medications prior to the next dose, on-off fluctuations, dyskinesias, etc.), and have no or little cognitive dysfunction.

Essential Tremor Candidates: Different centers will have different criteria that will be governed by regional regulatory approvals. For example, a medical center may consider Essential Tremor candidates for DBS must have medication refractory tremor defined as having failed maximal titrations and preferably combinations of a beta blocker, primidone, and possibly a benzodiazepine.

Other Disorders: Other disorders which may be addressed by DBS have been less studied in terms of selection criteria. This includes neuropsychological disorders. Eligibility will depend on the medical center.

Where can I find DBS Treatment?

The side-effects of DBS:

Although deep brain stimulation is minimally invasive and considered safe, any type of surgery has the risk of complications. Also, the brain stimulation itself can cause side effects. All the risks below are based on the article from Mayo Clinic 3.

Surgery risks

Deep brain stimulation involves creating small holes in the skull to implant the electrodes, and surgery to implant the device that contains the batteries under the skin in the chest. Complications of surgery may include:

• Misplacement of lead
• Bleeding in the brain
• Stroke
• Infection
• Breathing problems
• Nausea
• Heart problems
• Seizure

Possible side effects after surgery

Side effects associated with deep brain stimulation may include:

• Seizure
• Infection
• Headache
• Confusion
• Difficulty concentrating
• Stroke
• Hardware complications, such as an eroded lead wire
• Temporary pain and swelling at the implantation site

A few weeks after the surgery, the device will be turned on and the process of finding the best settings for you begins. Some settings may cause side effects, but these often improve with further adjustments of your device.

Possible side effects of stimulation

• Numbness or tingling sensations
• Muscle tightness of the face or arm
• Speech problems
• Balance problems
• Lightheadedness
• Vision problems, such as double vision
• Unwanted mood changes, such as anger and depression
• Temporary pain and swelling at the implantation site

Other adverse effects include apathy, hallucinations, hyper-sexuality, cognitive dysfunction, depression, and euphoria¹.

What are the parts of a Deep Brain Stimulation device?

A DBS device including a neurostimulator that generates the electrical therapy waveform. The electrical therapy waveform is transmitted with a wire under the skin to a lead implanted through the skull. The lead is insulated except for a certain location near the end call electrodes. The electrical stimulation from the neurostimulator device therefore exits at the electrode and enters the brain there.

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