Parkinson’s DBS: Deep Brain Stimulation and Candidate Selection

When medication stops doing what it used to, and shaking, stiffness, or freezing moments start taking over daily life, many people with Parkinson’s begin to wonder: is there something else? For thousands, the answer has been deep brain stimulation - or DBS. It’s not a cure. It doesn’t stop the disease. But for the right person, it can turn a life of unpredictable symptoms into one with real control. The question isn’t just whether DBS works - it’s whether you are the right candidate.

What Deep Brain Stimulation Actually Does

Deep brain stimulation isn’t magic. It’s a precise, surgical fix for a very specific problem: erratic brain signals. In Parkinson’s, certain areas of the brain - especially the subthalamic nucleus and globus pallidus - start firing in abnormal, rhythmic bursts. This is what causes tremors, slowness, and stiffness. DBS doesn’t remove these areas. Instead, it sends tiny, controlled pulses of electricity to them, like a pacemaker for the brain. These pulses smooth out the chaotic signals, letting movement return to a more normal rhythm.

The system has three parts: thin wires (electrodes) implanted into the brain, extension cables that run under the skin to the chest, and a battery-powered device (the pulse generator) usually placed near the collarbone. Modern devices, like Medtronic’s Percept™ PC or Boston Scientific’s Vercise™ Genus™, can even sense brain activity in real time. Some adjust stimulation automatically, based on whether the brain shows signs of tremor or freezing. This is called closed-loop DBS - and it’s changing how the treatment works.

For people who’ve been on levodopa for years, the difference can be dramatic. One study found that after DBS, patients cut their daily levodopa dose by nearly half. OFF time - those painful, stiff periods when meds wear off - dropped from six hours a day to under one. Dyskinesias - the wild, involuntary movements caused by too much medication - shrank by up to 80%. And quality of life scores jumped by over 20 points on a standard scale. That’s not minor. That’s life-changing.

Who Is a Good Candidate for DBS?

Not everyone with Parkinson’s is a candidate. DBS doesn’t work for everyone - and it’s not meant to. The best candidates share a few clear traits.

• They have idiopathic Parkinson’s - not atypical parkinsonism like progressive supranuclear palsy or multiple system atrophy. Those conditions don’t respond to DBS. If your symptoms don’t improve with levodopa, DBS won’t help either.
• They’ve had symptoms for at least five years. This isn’t arbitrary. It’s because doctors need to be sure the diagnosis is solid and that the person truly has motor complications, not just early-stage disease.
• They respond well to levodopa. A clear sign? When you take your pill, your movement improves by at least 30% on a standard motor exam. If you don’t see that kind of change, DBS likely won’t either.
• They don’t have serious cognitive issues. A Mini-Mental State Exam (MMSE) score below 24 or a MoCA score under 21 usually rules someone out. DBS can make memory or thinking problems worse, especially if they’re already there.
• They’re physically healthy enough for surgery. No major heart or lung problems. No uncontrolled depression or anxiety. These things increase risk and reduce benefit.

Many people are never even considered. The Parkinson’s Foundation estimates that fewer than 5% of eligible patients ever get referred for DBS screening. Too often, it’s only when things get really bad - when falls are frequent, speech is gone, or they’re stuck in bed for hours - that the idea comes up. But waiting too long can mean missing the window entirely.

STN vs. GPi: Choosing the Right Target

Two brain areas are most commonly targeted: the subthalamic nucleus (STN) and the globus pallidus interna (GPi). Both work well. But they have different strengths.

Most centers start with STN because it allows for bigger medication cuts - and fewer pills mean fewer side effects like nausea, hallucinations, or low blood pressure. But if someone already struggles with memory, mood, or speech, GPi may be safer. Studies show GPi causes fewer cognitive issues and gives better control over dyskinesias. The choice isn’t just medical - it’s personal. A 68-year-old who hates taking six pills a day might prefer STN. A 62-year-old who’s losing words mid-sentence might do better with GPi.

The Real-World Experience: What Patients Actually Say

Online forums are full of stories. Some are glowing. Others are raw.

One man, after STN DBS, said his OFF time dropped from six hours to one. His tremors vanished. He could hold a coffee cup again. But he started forgetting names. He’d stare at a word and blank out. He needed speech therapy. Another woman on Reddit said her hands stopped shaking, but now she couldn’t plan her week. “I used to cook meals. Now I just eat what’s easy.”

And then there’s the disappointment. Many expect DBS to stop the disease. It doesn’t. It doesn’t fix balance problems, speech softening, or constipation. It doesn’t help if you have freezing of gait that doesn’t respond to levodopa. One patient wrote: “I thought DBS would make me normal again. It didn’t. It just made my good days better.”

Still, the majority - 70 to 80% - report meaningful improvement. The biggest wins? Less shaking, fewer freezing spells, less medication, and more time doing things they love. One woman started gardening again. Another returned to painting. A retired teacher went back to volunteering. These aren’t small things. They’re the foundation of dignity.

The Process: What to Expect Before and After

Getting DBS isn’t a quick decision. It takes months.

1. Neurologist evaluation: Confirming Parkinson’s diagnosis and levodopa response. This usually involves a day-long motor exam - on and off meds.
2. Neuropsychological testing: Four to six hours of memory, attention, and mood tests. Depression, anxiety, or mild cognitive issues can delay or cancel surgery.
3. High-res MRI: A 3T scanner maps the brain to plan electrode placement. This isn’t optional. Poor targeting means poor results.
4. Team review: A neurologist, neurosurgeon, and neuropsychologist meet to decide if you’re a fit. Some centers require a second opinion.
5. Surgery: Two sessions (one for each side) under local anesthesia. You’re awake so the team can test responses. It takes 3-6 hours. Most go home in 1-2 days.
6. Programming: This is where patience matters. The first settings are just a starting point. It takes 6-12 months of adjustments - every few weeks at first - to find the sweet spot. You’ll need to keep a symptom diary: when you shake, when you freeze, when meds kick in.

After surgery, the battery lasts 9-15 years if it’s rechargeable. Non-rechargeable ones need replacing every 3-5 years. Hardware problems - like a broken wire or infection - happen in 5-15% of cases. Most are fixable, but they mean more surgery.

How DBS Compares to Other Options

There are alternatives - but none match DBS for broad symptom control.

• Lesioning (pallidotomy, thalamotomy): These destroy brain tissue. They’re permanent. One side only. They’re rarely used now because DBS is reversible and adjustable.
• Focused ultrasound: Non-invasive. Uses sound waves to burn a small spot in the brain. FDA-approved for tremor, but only on one side. Doesn’t help rigidity or bradykinesia as well. Best for tremor-dominant cases.
• Best medical therapy: Even the strongest meds can’t keep up with advanced PD. The EARLYSTIM trial showed DBS beat meds by a wide margin in quality of life.

DBS isn’t perfect. But for the right person, it’s the most powerful tool we have.

Why So Few People Get It

Over 15,000-20,000 DBS procedures are done each year worldwide. Sounds like a lot - until you realize there are over 10 million people with Parkinson’s. Only 1-5% of eligible patients get it.

Why? Several reasons:

• Many neurologists don’t bring it up until it’s too late.
• Patients fear brain surgery.
• Insurance takes months to approve.
• Not every hospital has a full DBS team - and outcomes drop sharply at low-volume centers.
• There’s no single standard for who qualifies. One center might say MMSE >24. Another says MoCA >21. Some require 10 years of disease. Others accept 5.

The Movement Disorders Society says DBS is “established as effective” - Level A evidence. That’s the highest level. Yet, most people never hear about it. That’s not a medical gap. It’s a system failure.

What’s Next? The Future of DBS

The field is moving fast. Closed-loop systems - that adjust stimulation based on brain signals - are already here. The Medtronic Percept™ PC can detect beta waves (linked to stiffness) and dial up stimulation only when needed. Early results show 27% better control than old-school DBS.

Researchers are testing DBS in people with just 3 years of Parkinson’s. Could earlier intervention prevent more damage? The EARLYSTIM-2 trial is trying to find out.

Some are even looking at non-motor symptoms. Can DBS help depression? Anxiety? Sleep? Early data is promising. And genetic testing might soon help predict who responds best - people with LRRK2 mutations, for example, show stronger improvement.

But the biggest shift? Personalization. No longer will we just look at tremors and levodopa response. We’ll look at gait, balance, sleep, mood, even handwriting. We’ll use wearables - like Apple Watch - to track tremor patterns at home and feed that data into the DBS device.

The goal isn’t just to control symptoms. It’s to restore life.