Deep Brain Stimulation (DBS) – Anesthetic Considerations


🔹 Introduction

Deep Brain Stimulation (DBS) is a neurosurgical procedure involving the implantation of electrodes into specific brain targets, which deliver chronic electrical impulses to modulate abnormal neuronal circuits.

It is a reversible, programmable, and adjustable alternative to destructive neurosurgical procedures (e.g., thalamotomy or pallidotomy), particularly useful for movement disorders.


🔹 Indications for DBS

Disease

Target Area

Parkinson’s Disease (PD)

Subthalamic nucleus (STN), Globus pallidus internus (GPi)

Essential Tremor

Ventral intermediate nucleus (VIM) of thalamus

Dystonia

GPi

Tourette’s Syndrome

Centromedian nucleus, GPi

Obsessive Compulsive Disorder (OCD)

Ventral capsule/ventral striatum

Depression (experimental)

Subgenual cingulate gyrus



🔹 Components of the DBS System

  1. Implanted Electrodes: Placed into target nuclei via stereotactic guidance
  2. Extension Wires: Connect the electrodes to the pulse generator
  3. Implantable Pulse Generator (IPG): Usually placed subcutaneously in the chest or abdomen


🔹 Procedure Stages

  1. Stereotactic Frame Placement (Under LA ± sedation)
  2. Imaging (MRI/CT for targeting)
  3. Electrode Insertion (Awake for mapping or under GA in some centers)
  4. Intraoperative Testing (for motor/speech response, side effects)
  5. IPG Implantation (usually under GA on same or subsequent day)


🔹 Anesthetic Considerations: Overview

Anesthetic goals differ depending on whether the procedure is awake or asleep, but always prioritize:

  • Minimal interference with neurophysiologic monitoring
  • Maintenance of patient cooperation
  • Hemodynamic and respiratory stability
  • Avoiding drug-induced movement or suppression of tremor


🔸 Awake DBS

Preferred for Parkinson’s and essential tremor, allows intraoperative testing and precise electrode placement

🧠 Benefits

  • Real-time neurophysiological feedback
  • Better electrode localization
  • Detection of adverse stimulation effects

🔹 Preoperative Considerations

  • Discontinue dopaminergic drugs (e.g., levodopa) night before surgery to unmask tremor for better targeting
  • Detailed neurological and airway assessment
  • Psychological preparation is crucial
  • Explain steps to ensure patient cooperation

🔹 Sedation Strategy

Drug

Rationale

Dexmedetomidine

Sedation with minimal respiratory depression; preserves neurophysiological signals

Remifentanil

Analgesia with rapid offset

Avoid: Propofol, benzodiazepines, volatile agents

Suppress tremor, affect neuron firing & test accuracy


🔹 Intraoperative Management

  • Scalp block with 0.25% bupivacaine or ropivacaine + epinephrine
  • Sedation during frame placement and burr hole
  • Stop sedation during mapping phase (patient awake)
  • Monitor for nausea, agitation, pain, or seizure


🔸 General Anesthesia (Asleep DBS)

Indicated in:

  • Children
  • Patients unable to cooperate
  • Psychiatric illness
  • Dystonia (involuntary movements interfere with targeting)

🔹 Challenges

  • Suppression of neural firing by anesthetics
  • Inaccurate targeting without feedback
  • Intraoperative MRI targeting may compensate

🔹 Anesthetic Technique

  • Total Intravenous Anesthesia (TIVA) preferred
  • Avoid volatile agents and nitrous oxide
  • Use:
    • Propofol infusion (low dose)
    • Short-acting opioids (remifentanil)
    • Avoid long-acting muscle relaxants—use short-acting (e.g., succinylcholine) only if needed
  • Maintain spontaneous ventilation when possible


🔸 IPG (Pulse Generator) Implantation

  • Usually performed under general anesthesia
  • Electrode wires tunneled subcutaneously to the chest
  • Minimal anesthetic concerns


🔹 Monitoring

Modality

Role

ECG, NIBP, SpO₂

Standard

Capnography (if sedated)

Detect hypoventilation

Bispectral Index (BIS)

Depth of sedation/GA

Microelectrode Recording (MER)

Requires minimal anesthetic interference

Electrophysiology Testing

Motor/speech effects of stimulation



🔹 Drug Considerations

Drug Type

Consideration

Dopaminergic (levodopa)

Hold pre-op for tremor; resume post-op to avoid “off” state

Anticholinergics

May impair cognition

Antiemetics

Avoid dopamine antagonists (e.g., metoclopramide); use ondansetron

Muscle relaxants

Avoid long-acting; interfere with MEPs/EMG

Volatiles

Suppress neuron activity—avoid if MER used



🔹 Potential Complications

Complication

Cause/Management

Seizures

Cortical penetration—treat with benzodiazepines

Intracranial hemorrhage

Burr hole or electrode trauma—monitor postop imaging

Air embolism

Avoid nitrous oxide, maintain head-up position

Pneumocephalus

Avoid N₂O

Airway obstruction (during awake phase)

Jaw thrust, NPA

Nausea/vomiting

Pre-op antiemetics

Device malfunction

Ensure generator function; avoid cautery near device



🔹 Special Concerns: MRI Compatibility

  • DBS devices can be MRI conditional
  • If MRI is planned:
    • Confirm compatibility
    • Turn off the IPG before scan
    • Avoid monopolar cautery near leads


🔍 Viva Points / Key Facts

  • ✅ DBS allows reversible neuromodulation unlike ablation
  • ✅ Most common DBS target in Parkinson’s = Subthalamic nucleus (STN)
  • ✅ Avoid agents that mask tremor or suppress neuron firing
  • ✅ Dexmedetomidine is the sedative of choice for awake DBS
  • ✅ MER is used to identify proper electrode location
  • ✅ Post-op CT scan to check for hemorrhage or lead displacement



📚 References

  • Miller’s Anesthesia, 9th Edition – Chapter on Functional Neurosurgery
  • Cottrell and Young’s Neuroanesthesia
  • BJA Education: Anesthesia for Deep Brain Stimulation
  • StatPearls: Deep Brain Stimulation
  • WFSA Tutorial: Anesthesia for Stereotactic Neurosurgery