What is Deep brain stimulation?
DBS for shortTechnique used since late 1980sUses electrical impulses to stimulate a target area in the brain• As a result: Alters the activity in the targeted area, blocking abnormal nerve signals
that cause unwanted symptoms
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Why DBS?
Why do we need DBS?Known to be beneficial for treating wide range of diseases:• Most common use is for movement disorders: Parkinson’s disease (PD), Essential
Tremor (ET), dystonia• Recently started being used for psychiatric disorders: OCD, Depression• Cognitive disorders, Chronic pain, Epilepsy
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VIM
AnatomyTargeted Brain Sites
Locations of DBS implantation needs to be approved by FDAThe most common and effective targeted areas:• Subthalamic nucleus (STN): largest part of subthalamus• GPi: Internal segment of globus pallidus• Thalamus (VIM)• Subcallosal Cingulate (SCC)
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Physiology
, Motor control
VIM
Physiology:STN: autonomous, non-linear, fast-spiking pacemaker• Function: Motor control and impulse control GPi:• inhibits nuclei needed for movement planning: prevents unwanted movementsVIM:• coordination and planning of movementSCC: • regulates emotion
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Pathology
Pathology
STN: Normally fire spontaneously and non-linearly in the presence of dopamine• Synchronous activity due to loss of dopamine cells: Principal cause of PD, ET, OCDGpi: • Firing probability decreased in PD patient: Cause of ETVIM: • Decrease in spikes causes tremor
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DBS Components
3 Main parts: IPG: (neurostimulator) deliver electrical stimulation to specific areas in the brain that control movement Lead: thin, insulated wire implanted in the brain. Extension: insulated wire that is passed under the skin of the head, neck, and shoulder, connecting the lead to the IPG.
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Types of DBS Lead
Location of the lead contacts in brain important for optimizing result and minimizing side effectsA: Four contacts: classic lead designB: directional contact: increases ability to steer electrical stimulation toward symptoms and away from side effects. C: Eight contacts: deliver and control electrical stimulation more precisely
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Types of DBS Neurostimulator
Choice between rechargeable vs non-rechargeable battery• Rechargeable batteries: last up to 15 years
• less surgical procedures to replace them • Require daily or weekly recharging
• Non-rechargeable batteries: last 3-5 years depending on individual patients’ settings
• Require replacement surgery whenever battery runs out
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Patient Selection
Patients that qualify for DBS: • Symptoms for over 5 years and doesn’t respond to medications anymore • Symptoms interfere with daily activities• Patients who can’t have epilepsy surgery: separates or removes the part of the
brain that causes seizures
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Procedure Placement of DBS Lead
Surgery consist of 2 stages
First stage: placement of DBS Lead • MRI prior to surgery to plan• CT scan with head frame to map out placement for the DBS leads on the day of
surgery• Test electrode used during surgery
• MER (Microelectrode recording) to check if the placement is optimal• Patient awake: asked to perform simple motor tests
• DBS lead is placed
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Procedure Insertion of Neurostimulator
Second stage: Insertion of neurostimulator• Usually done few days after DBS lead placement• Neurostimulator is placed in the patient’s chest
• Portion of scalp re-opened to attach lead with extension -> which thenattaches to the neurostimulator
• Not turned on immediately: ~10 days after the surgery• Stimulator programmed: require about 3-4 programming sessions to
maximize results
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Result of DBS
Parkinson’s disease (PD) Essential Tremor (ET)
Factors that determine success in DBS:• Appropriate patient selection• Appropriate lead placement• Appropriate programming of stimulator and management
From 2018 data: 1) Psychiatric disorders show promising results 2) 75% of PD patient felt improvement in symptoms3) ET patients: significantly reduced hand and voice tremor but few found symptoms
worsening
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Advantages of DBS
Efficient and Safe
Implanting instead of removing
Adjustable
Reversible
Symptom Reduction:• Improvement in motor symptoms, mood and quality of life Little Damage:• Doesn’t damage or remove nerve cells (epilepsy surgery) • Reversible surgery: lead can be removed without damage Adjustable Treatment:• stimulation intensity can be controlled by physicians
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Limitations of DBS
Limitations of DBS:ExpensiveResults Aren’t Immediate
Surgery risks:• Misplacement of lead• Bleeding in the brain, Stroke, Infection
Post surgery risks:• Infection• Headache• Stroke• lead migration (next slide)
Stimulation risks:• Numbness• Worsening symptoms: Speech problems, Balance problems are the most common• Unwanted mood changes, such as anger and depression
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Long-Term Lead Migration
One of the most common long term issue is lead migration:• Over 10% of DBS leads shown to be displaced by greater than 3 mm
• affects on the outcome
Factors associated with lead migration:• Failure of fixation at the hole site during surgery • technical error during implantation of pulse generator• repetitive dystonic head movement
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Current Research
Currently stimulated in an open-loop manner:• Stimulation parameters are pre-programmed • Not responsive to changes in patient’s symptoms • Limitations in overall efficiency: adjustment is time consuming
Going forward, Closing the loop:• Through real-time communication to the implanted neurostimulator • Adjust on its own in response to individual’s brain signals • Would reduce side effects from unneeded stimulation
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Manufacturing Companies
Companies with FDA (U.S. Food and Drug Administration) approved DBS devices: • Medtronic: first to be FDA approved in 1997
• Rechargeable batteries: last up to 15 years• Non-rechargeable devices: last 3-5 years
• Boston Scientific: FDA approved in 2017• Vercise’s brain leads: 8 contact• Rechargeable battery: last up to 25 years
• Abbott: FDA approved in 2016• Infinity brain leads: directional stimulation
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Future of DBS• closed loop controlled DBS• Improved longevity• Reduction in size, cost• Lower risk implementation
Market growth drivers:• Increasing number of patients suffering from movement and psychiatric disorders• Increasing demand for minimally invasive techniques (compared to other
surgeries)
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Economic Consideration
Economic considerations:Cost of DBS care: • Up to $50,000: not including the care required in the future
• Replacement of battery every 3-5 years, device malfunction, lead migration• Some insurance plans cover the cost for Parkinson’s disease
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Conclusion
ConclusionDBS is an effective surgical treatment for various movement and psychiatric disorders with long-term benefits • Increase 10 + years of PD patient’s independencyFurther research in this field is critical to gain further insight in:• new brain target sites with better outcomes• More variety in disorders it can treat• How to optimize outcomes while decreasing the price
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Questions?
Questions
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References
• https://thejns.org/view/journals/j-neurosurg/131/2/article-p333.xml
• https://www.sciencedirect.com/science/article/pii/S1935861X19304668
• https://www.medicalnewstoday.com/articles/318534
• https://www.healthlinkbc.ca/health-topics/hw90970
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5565669/
• https://www.davisphinneyfoundation.org/blog/life-before-after-deep-brain-stimulation-dbs/
• https://www.sciencedirect.com/science/article/pii/B9780123742483000422
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