Dr.Amr Sobhy Anesthesia and Deep Brain Stimulation

Dr.Amr SobhyDr.Amr Sobhy

Anesthesia and Deep Brain Stimulation

ObjectivesObjectives

Brief HistoryBrief History Indications and contra-Indications and contra-

indicationsindications The DBS surgical procedureThe DBS surgical procedure Anesthetic considerationAnesthetic consideration Anesthetic techniqueAnesthetic technique Safety issuesSafety issues

Brief HistoryBrief History

Basal ganglia have been targeted for neuromodulator Basal ganglia have been targeted for neuromodulator surgery since the 1930s.surgery since the 1930s.

1950s: Pallidotomy was the accepted procedure for the 1950s: Pallidotomy was the accepted procedure for the treatment of Parkinsonism Disease (PD).treatment of Parkinsonism Disease (PD).

procedures were irreversible and were associated with procedures were irreversible and were associated with several permanent side effects.several permanent side effects.

With the advent of L-dopa (1968),this surgery largely With the advent of L-dopa (1968),this surgery largely stopped.stopped.

Limitations of dopaminergic therapy led to a resurgence Limitations of dopaminergic therapy led to a resurgence of new surgical techniques directed at basal ganglia of new surgical techniques directed at basal ganglia targets in early 1990s.targets in early 1990s.

Brief HistoryBrief History

Today, DBS has become a non-lesioning alternative to Today, DBS has become a non-lesioning alternative to pallidotomy.pallidotomy.

1993: Bilateral high-frequency stimulation of 1993: Bilateral high-frequency stimulation of subthalamic nucleus (STN) introduced in treatment of subthalamic nucleus (STN) introduced in treatment of advanced PD advanced PD

Pioneering studies & empirical observations during Pioneering studies & empirical observations during surgery showed that DBS improved PD patient’s motor surgery showed that DBS improved PD patient’s motor function and quality of life.function and quality of life.

What is DBS?What is DBS?

A surgically implanted A surgically implanted medical device called a medical device called a brain pacemaker.brain pacemaker.

Sends electrical Sends electrical impulses to the brain.impulses to the brain.

Traditionally used to Traditionally used to treat movement treat movement disorders such as disorders such as

chronic pain, chronic pain, Parkinson’s Parkinson’s disease, tremor, disease, tremor, and dystoniaand dystonia..

MechanismMechanism

The exact mechanism is The exact mechanism is incompletely understood .incompletely understood .

may differ depending on the site may differ depending on the site of stimulation, The primary of stimulation, The primary target sites :target sites :

1. Vim = ventralis intermedius nucleus of the thalamus

2. GPi = posteroventral portion of the internal segment of the globus pallidus

3. STN = subthalamic nucleus

MechanismMechanism

stimulation of the stimulation of the STN STN causes causes hyperpolarization or “neuronal jamming,” hyperpolarization or “neuronal jamming,” and this consequentially results in the and this consequentially results in the inhibition of its activity.inhibition of its activity.

Stimulation of the Stimulation of the GPiGPi nuclei may result in nuclei may result in activation (GABA)ergic axons, which in turn activation (GABA)ergic axons, which in turn inhibits GPi neurons.inhibits GPi neurons.

In contrast, stimulation of the In contrast, stimulation of the VimVim nucleus nucleus of the thalamus activates output to the of the thalamus activates output to the neurons in the reticular nucleus, which then neurons in the reticular nucleus, which then sends inhibitory efferent back to the sends inhibitory efferent back to the thalamic nuclei.thalamic nuclei.

Contra-indicationsContra-indications

patients clearly have to be fit patients clearly have to be fit enough to undergo the surgery enough to undergo the surgery and well enough to benefit from and well enough to benefit from it. it.

The major concern is of The major concern is of coagulopathies, as this would coagulopathies, as this would increase the risk of hemorrhage increase the risk of hemorrhage with the electrode insertionwith the electrode insertion

Three Major Three Major ComponentsComponents

Implanted pulse generator Implanted pulse generator (IPG)(IPG) battery-powered neurostimulator battery-powered neurostimulator

encased in a titanium housing, encased in a titanium housing, which sends electrical pulses to which sends electrical pulses to the brain to interfere with neural the brain to interfere with neural activity at the target siteactivity at the target site

LeadLead coiled wire insulated in coiled wire insulated in

polyurethane with four platinum polyurethane with four platinum iridium electrodes and is placed in iridium electrodes and is placed in one of three areas of the brainone of three areas of the brain

ExtensionExtension insulated wire that runs from the insulated wire that runs from the

head, down the side of the neck, head, down the side of the neck, behind the ear to the IPG, which is behind the ear to the IPG, which is placed subcutaneously below the placed subcutaneously below the clavicle or in some cases, the clavicle or in some cases, the abdomenabdomen

ComponentsComponents

The DBS surgical The DBS surgical procedureprocedure


Precise implantation of stimulation Precise implantation of stimulation electrode in targeted brain area.electrode in targeted brain area.

Connecting electrode to internal Connecting electrode to internal programmable pulse generatorprogrammable pulse generator


Pre-Operative Stage:Pre-Operative Stage: Stereotactic SurgeryStereotactic Surgery

- Locate targeted brain areas- Locate targeted brain areas

- Stereotactic frame- Stereotactic frame

- MRI, CT, or ventriculography- MRI, CT, or ventriculography

- Stereotactic atlas- Stereotactic atlas


Pre-Operative Stage:Pre-Operative Stage: Functional Stereotactic Functional Stereotactic

SurgerySurgery- Electrophysiological - Electrophysiological exploration of targeted regions exploration of targeted regions via test electrodesvia test electrodes

- Involves:- Involves:

1. Microrecording 1. Microrecording

2. Test-stimulation2. Test-stimulation


Electrode Electrode Extension Extension (passed under skin to chest) (passed under skin to chest) Chest: Battery-operated Chest: Battery-operated stimulatorstimulator

Patient turns stimulator “on” Patient turns stimulator “on” and “off” by passing magnet and “off” by passing magnet over the skin overlying over the skin overlying stimulator stimulator

Typical stimulator settings:Typical stimulator settings:

- Voltage amplitude: 2-3 V- Voltage amplitude: 2-3 V

- Pulse width: 90 - Pulse width: 90 μμss

- Stimulation frequency: 130-- Stimulation frequency: 130-185 Hz185 Hz

Electrode-Stimulator Connection:Electrode-Stimulator Connection:

Anesthetic considerationAnesthetic consideration

1- Patient-related considerations1- Patient-related considerationsPrimary disease (Parkinson disease, dystonia, Primary disease (Parkinson disease, dystonia, essential tremors, chronic pain, and epilepsy)essential tremors, chronic pain, and epilepsy)Comorbid medical conditions of patient and of Comorbid medical conditions of patient and of disease disease Age (children and elderly)Age (children and elderly) Appropriate patient selection and preparationAppropriate patient selection and preparationPolypharmacy and altered pharmacokinetics and Polypharmacy and altered pharmacokinetics and dynamicsdynamicsPotential drug interactions Potential drug interactions Medication “off state”— worsening of symptomsMedication “off state”— worsening of symptoms


2- Procedure-related considerations2- Procedure-related considerationsDifferent locations of patient care (magnetic Different locations of patient care (magnetic resonance imaging and operating room)resonance imaging and operating room)Use of a stereotactic frame: potential for Use of a stereotactic frame: potential for difficult airwaydifficult airwayPositioning of patient on the operating room Positioning of patient on the operating room table: difficult with movement disorderstable: difficult with movement disordersSemisitting position: risk of venous air embolism Semisitting position: risk of venous air embolism and hypovolemiaand hypovolemiaBlood pressure control: prevention of Blood pressure control: prevention of hemorrhage from hypertension during electrode hemorrhage from hypertension during electrode insertioninsertion


Microelectrode recordings: anesthetic Microelectrode recordings: anesthetic effects may impaireffects may impair

Macro stimulation testing: need for an Macro stimulation testing: need for an awake and cooperative patientawake and cooperative patient

Long duration of procedure: patient fatigueLong duration of procedure: patient fatigue Complications: airway obstruction, seizures, Complications: airway obstruction, seizures,

neurologic neurologic deterioration, and hypertensiondeterioration, and hypertension

Anesthetic techniqueAnesthetic technique

Anesthetic managementAnesthetic management

Stage of FramingStage of Framing

Overall, the majority of patients tolerate the insertion of DBS using a combination of local anesthesia and sedation/analgesia infusion of dilute Remifentanil usually 0.02–0.05 mg/ kg/ min OR Dexametamedonie usually 0.4-0.7µg/ kg/ hOxygen is provided by a microphone supply attached to the underside of the frame, and music of the patient’s choice played to aid relaxation.


Stage of ImagingStage of Imagingthe anesthetist is equipped the anesthetist is equipped with the tool to remove the with the tool to remove the fixing screws, in case the fixing screws, in case the frame needs to be removed frame needs to be removed for access to the airwayfor access to the airway


Stage of implantationStage of implantationAwake: an infusion of remifentanil as an infusion of remifentanil as above, while full monitoring and above, while full monitoring and supplemental oxygen is provided. supplemental oxygen is provided. Benzodiazepines are avoided Benzodiazepines are avoided G.A: typically a target-controlled typically a target-controlled infusion of propofol and remifentanil infusion of propofol and remifentanil and a non-depolarizing neuromuscular and a non-depolarizing neuromuscular block technique is used.block technique is used.If the patient has Parkinson’s If the patient has Parkinson’s disease, then it is prudent to insert a disease, then it is prudent to insert a naso-gastric tubenaso-gastric tube

Safety IssuesSafety Issues

G.A & R.AG.A & R.Aavoiding drugs with extra-pyramidal side-effects avoiding drugs with extra-pyramidal side-effects

in this group of patientsin this group of patients. . Peripheral nerve stimulators can still be used Peripheral nerve stimulators can still be used

MRI scanningMRI scanningHeating, Magnetic field interactions and DBS function This can produce Unintended stimulation thermal lesions possibly resulting in coma, paralysis, or death.contraindicated

.


DiathermyDiathermyCan damage the DBS leads and can also Can damage the DBS leads and can also cause temporary suppression of the cause temporary suppression of the neurostimulator.neurostimulator.use bipolar diathermy.use bipolar diathermy. if unipolar diathermy is necessary:if unipolar diathermy is necessary:

(a) use only a low-voltage mode.(a) use only a low-voltage mode.

(b) use the lowest possible power setting.(b) use the lowest possible power setting.

(c) keep the current path (ground plate) as far (c) keep the current path (ground plate) as far from the neurostimulator from the neurostimulator

(d)After using diathermy, confirm that the (d)After using diathermy, confirm that the neurostimulator is functioning as intendedneurostimulator is functioning as intended


External defibrillationExternal defibrillationposition defibrillation paddles as far from the position defibrillation paddles as far from the

neurostimulator as possibleneurostimulator as possible. . position defibrillation paddles perpendicular position defibrillation paddles perpendicular to the implanted neurostimulator-lead system. to the implanted neurostimulator-lead system. use the lowest clinically appropriate energy use the lowest clinically appropriate energy output.output.Confirm that the DBS is functioning correctly Confirm that the DBS is functioning correctly after any external defibrillation.after any external defibrillation.


Electroconvulsive therapyElectroconvulsive therapyECT may be a safe and effective ECT may be a safe and effective option.option.Care in placing the ECT Care in placing the ECT electrodes.electrodes.Switching the DBS off before ECT.Switching the DBS off before ECT.Limiting the number of ECT Limiting the number of ECT sessions should be considered.sessions should be considered.

Any Any Questions?Questions?

summarysummary

DBS is the pace maker of the brain.DBS is the pace maker of the brain. Anesthetic consideration of PD Anesthetic consideration of PD

during insertion should be consider during insertion should be consider especially withholding of the drugs especially withholding of the drugs and early resume postoperatively.and early resume postoperatively.

Dealing with patient have DBS Dealing with patient have DBS devise need especial care as devise need especial care as

regard electromagnetic regard electromagnetic interference (MRI-Diathermy-interference (MRI-Diathermy-

External defibrillation).External defibrillation).

Thank youThank you

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Dr.Amr Sobhy Anesthesia and Deep Brain Stimulation