Deep brain stimulation is usually considered for Parkinson's disease when medication still works well — but no longer works steadily. The typical candidate has clear benefit during ON periods, together with wearing-off, unpredictable OFF periods or medication-induced dyskinesia that medication adjustment can no longer solve. In Prof. YILMAZ's series, average motor improvement has been 80% or greater and average medication reduction 50% or greater; individual results vary.
At a glance
- Usual targets
- Subthalamic nucleus (STN) or globus pallidus internus (GPi)
- Best predictor of benefit
- How well symptoms respond to levodopa during a formal ON/OFF assessment
- Typical candidate
- Fluctuating response, dyskinesia or tremor not controlled by medication; good cognition; realistic expectations
- Average motor improvement
- ≥80% (our case series — results vary)
- Average medication reduction
- ≥50% (our case series — results vary)
- Hospital stay
- Usually 3–5 days; programming continues for several months
- What DBS does not improve
- Symptoms that never respond to medication — balance and falls, freezing unresponsive to levodopa, cognitive decline, speech in most patients
The single most useful question
Before anything else, one question predicts the outcome of surgery better than any scan: how well does the patient respond to medication on a good day? Deep brain stimulation reproduces, steadily and around the clock, the benefit that medication already produces intermittently. It very rarely creates a benefit that medication has never produced.
This is why a formal medication-ON / medication-OFF assessment — examining the patient after withholding medication overnight, then again after a dose — is the core of candidacy evaluation. Tremor is the one common exception: tremor that resists medication can still respond very well to stimulation.
When is it too early, and when is it too late?
Too early: when medication still gives smooth, predictable control all day. There is nothing for stimulation to improve, and the risks are not justified.
The right window: when ON periods are still good but are becoming shorter, less predictable, or are accompanied by dyskinesia; when the day is being organised around medication timing; when doses are increasing without buying more good hours.
Too late: when the dominant problems are those levodopa never helped — falls, freezing that does not improve in the ON state, swallowing difficulty, hallucinations or significant cognitive impairment. At that stage stimulation adds risk without adding much benefit, and a good surgeon will say so.
STN or GPi?
| Subthalamic nucleus (STN) | Globus pallidus internus (GPi) | |
|---|---|---|
| Typical strength | Largest medication reduction; strong effect on rigidity, bradykinesia and tremor | Direct suppression of dyskinesia; often kinder to mood and cognition |
| Often preferred when | Medication burden is high and cognition and mood are good | Dyskinesia dominates, or there are mood, behavioural or borderline cognitive concerns |
| Medication reduction | Usually greater | Usually smaller |
| Programming | Narrower therapeutic window; more technically demanding | Wider window; often more forgiving |
There is no universally better target. The choice is made per patient after neurological, neuropsychological and psychiatric assessment. In selected tremor-dominant patients with severe dyskinesia, Prof. YILMAZ has used an asymmetric approach — one GPi and one STN electrode — to address both components.
What the surgery involves
- Planning. High-resolution MRI and CT are fused and the target coordinates are calculated on the individual patient's anatomy.
- Implantation. Electrodes are placed through small skull openings using a stereotactic frame. Depending on the plan, microelectrode recording and intraoperative test stimulation are used to confirm position — part of the procedure may be done awake so that benefit and side effects can be checked directly.
- Pulse generator. A battery-powered generator is placed under the skin below the collarbone and connected to the electrodes, usually under general anaesthesia.
- Programming. Stimulation is switched on and refined over weeks to months, with medication reduced in parallel. This stage determines the result as much as the surgery does.
Risks, stated plainly
DBS is brain surgery. The most serious risk is intracranial haemorrhage, reported in approximately 1–2% of patients in large series, which can cause permanent deficit. Infection of the implanted system occurs in a few per cent and sometimes requires removing the hardware. Hardware can fracture or migrate. Stimulation itself can cause speech changes, paraesthesia, mood or impulse-control changes, or weight gain; most of these are adjustable by reprogramming. Batteries need replacement — rechargeable systems typically last far longer than non-rechargeable ones.
If you are not able to travel for assessment
Most international patients are assessed remotely first. What is needed: the treating neurologist's report and current medication list, recent brain MRI, and short videos recorded in the medication-OFF state (before the first morning dose) and the medication-ON state. Prof. YILMAZ reviews these personally and replies with a written opinion, including when the answer is that surgery is not advisable.
Request a DBS candidacy review
Outcome figures are averages drawn from this practice's consecutive series of more than 800 deep brain stimulation procedures performed by Prof. Atilla YILMAZ, MD and his team. Results vary between patients and no outcome is guaranteed. Haemorrhage and infection rates quoted are from published large DBS series, not from this centre's own data.
Frequently asked questions
How much does DBS improve Parkinson's symptoms?
In the case series of Prof. Atilla YILMAZ, MD, average motor improvement has been 80% or greater and average medication reduction 50% or greater. These are averages; individual results vary and depend heavily on how well symptoms respond to medication before surgery.
What is the best age for DBS in Parkinson's disease?
Age alone is not the deciding factor — biological condition, cognition and medication response matter more. Many centres are more cautious above roughly 70–75 years because cognitive and balance problems become more common, but carefully selected older patients do benefit.
Will I be able to stop my Parkinson's medication after DBS?
Usually not completely. Most patients reduce their dose substantially — on average by half or more in this practice — but stopping medication entirely is uncommon and is not the goal of surgery.
Is the patient awake during DBS surgery?
Often partly. Being awake during electrode placement allows tremor, rigidity and side effects to be tested directly, which improves lead placement. The generator implantation is done under general anaesthesia. Fully asleep, image-guided surgery is possible in selected patients.
Does DBS stop Parkinson's disease from progressing?
No. DBS controls symptoms; it does not slow or stop the underlying disease. Symptoms that stimulation does not address — particularly balance, freezing that does not respond to medication, and cognition — continue to progress.