1. Anesthesia and Deep Brain Stimulation
Dr.Amr Sobhy

2. Objectives Brief History Indications and contra-indications
The DBS surgical procedure
Anesthetic consideration
Anesthetic technique
Safety issues

3. Brief History
Basal ganglia have been targeted for neuromodulator surgery since the 1930s.
1950s: Pallidotomy was the accepted procedure for the treatment of Parkinsonism Disease (PD).
procedures were irreversible and were associated with several permanent side effects.
With the advent of L-dopa (1968),this surgery largely stopped.
Limitations of dopaminergic therapy led to a resurgence of new surgical techniques directed at basal ganglia targets in early 1990s.

4. Brief History
1993: Bilateral high-frequency stimulation of subthalamic nucleus (STN) introduced in treatment of advanced PD
Pioneering studies & empirical observations during surgery showed that DBS improved PD patient’s motor function and quality of life.
Today, DBS has become a non-lesioning alternative to pallidotomy.

5. What is DBS?
A surgically implanted medical device called a brain pacemaker.
Sends electrical impulses to the brain.
Traditionally used to treat movement disorders such as chronic pain, Parkinson’s disease, tremor, and dystonia.

6. Mechanism The exact mechanism is incompletely understood .
may differ depending on the site of stimulation, The primary target sites :
Vim = ventralis intermedius nucleus of the thalamus
GPi = posteroventral portion of the internal segment of the globus pallidus
STN = subthalamic nucleus

7. Mechanism
stimulation of the STN causes hyperpolarization or “neuronal jamming,” and this consequentially results in the inhibition of its activity.
Stimulation of the GPi nuclei may result in activation (GABA)ergic axons, which in turn inhibits GPi neurons.
In contrast, stimulation of the Vim nucleus of the thalamus activates output to the neurons in the reticular nucleus, which then sends inhibitory efferent back to the thalamic nuclei.

8. Contra-indications
patients clearly have to be fit enough to undergo the surgery and well enough to benefit from it.
The major concern is of coagulopathies, as this would increase the risk of hemorrhage with the electrode insertion

9. Components Three Major Components Implanted pulse generator (IPG) Lead
battery-powered neurostimulator encased in a titanium housing, which sends electrical pulses to the brain to interfere with neural activity at the target site
Lead
coiled wire insulated in polyurethane with four platinum iridium electrodes and is placed in one of three areas of the brain
Extension
insulated wire that runs from the head, down the side of the neck, behind the ear to the IPG, which is placed subcutaneously below the clavicle or in some cases, the abdomen

10. The DBS surgical procedure

11. The DBS surgical procedure
Precise implantation of stimulation electrode in targeted brain area.
Connecting electrode to internal programmable pulse generator

12. The DBS surgical procedure
Pre-Operative Stage:
Stereotactic Surgery
- Locate targeted brain areas
- Stereotactic frame
- MRI, CT, or ventriculography
- Stereotactic atlas

13. The DBS surgical procedure
Pre-Operative Stage:
Functional Stereotactic Surgery
- Electrophysiological exploration of targeted regions via test electrodes
- Involves:
1. Microrecording
2. Test-stimulation

14. The DBS surgical procedure
Electrode-Stimulator Connection:
Electrode  Extension (passed under skin to chest)  Chest: Battery-operated stimulator
Patient turns stimulator “on” and “off” by passing magnet over the skin overlying stimulator
Typical stimulator settings:
- Voltage amplitude: 2-3 V
- Pulse width: 90 μs
- Stimulation frequency: Hz

15. Anesthetic consideration
1- Patient-related considerations
Primary disease (Parkinson disease, dystonia, essential tremors, chronic pain, and epilepsy)
Comorbid medical conditions of patient and of disease
Age (children and elderly)
Appropriate patient selection and preparation
Polypharmacy and altered pharmacokinetics and dynamics
Potential drug interactions
Medication “off state”— worsening of symptoms

16. Anesthetic consideration
2- Procedure-related considerations
Different locations of patient care (magnetic resonance imaging and operating room)
Use of a stereotactic frame: potential for difficult airway
Positioning of patient on the operating room table: difficult with movement disorders
Semisitting position: risk of venous air embolism and hypovolemia
Blood pressure control: prevention of hemorrhage from hypertension during electrode insertion

17. Anesthetic consideration
Microelectrode recordings: anesthetic effects may impair
Macro stimulation testing: need for an awake and cooperative patient
Long duration of procedure: patient fatigue
Complications: airway obstruction, seizures, neurologic deterioration, and hypertension

18. Anesthetic technique

19. Anesthetic management
Stage 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 µg/ kg/ h
Oxygen is provided by a microphone supply attached to the underside of the frame, and music of the patient’s choice played to aid relaxation.

20. Anesthetic management
Stage of Imaging
the anesthetist is equipped with the tool to remove the fixing screws, in case the frame needs to be removed for access to the airway

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

22. Safety Issues
G.A & R.A
avoiding drugs with extra-pyramidal side-effects in this group of patients.
Peripheral nerve stimulators can still be used
MRI scanning
Heating, Magnetic field interactions and DBS function This can produce Unintended stimulation thermal lesions possibly resulting in coma, paralysis, or death.
contraindicated .

23. Safety Issues Diathermy
Can damage the DBS leads and can also cause temporary suppression of the neurostimulator.
use bipolar diathermy.
if unipolar diathermy is necessary:
(a) use only a low-voltage mode.
(b) use the lowest possible power setting.
(c) keep the current path (ground plate) as far from the neurostimulator
(d)After using diathermy, confirm that the neurostimulator is functioning as intended

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

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

26. Any Questions?

27. summary DBS is the pace maker of the brain.
Anesthetic consideration of PD during insertion should be consider especially withholding of the drugs and early resume postoperatively.
Dealing with patient have DBS devise need especial care as regard electromagnetic interference (MRI-Diathermy-External defibrillation).

28. Thank you