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

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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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