Awake Craniotomy – Anesthetic Considerations

🔹 Introduction

Awake craniotomy is a specialized neurosurgical technique where the patient remains awake and cooperative during parts of the brain surgery, especially when resection involves eloquent areas such as motor cortex, speech centers, or sensory regions.

The primary goal is to maximize tumor/lesion resection while minimizing postoperative neurological deficits.


🔹 Indications

Clinical Scenario

Reason for Awake Technique

Gliomas near eloquent cortex

Real-time neurological testing

Epilepsy surgery

Localization and resection of seizure focus

Deep brain stimulation (DBS)

Functional mapping and adjustment

Arteriovenous malformation (AVM)

Preserve function near critical areas

Language mapping

Dominant hemisphere tumors (Broca’s, Wernicke’s areas)



🔹 Advantages

  • Real-time mapping of motor, sensory, and language functions
  • Maximal safe resection of lesions
  • Avoids risks associated with general anesthesia and airway management
  • Reduced ICU stay, faster recovery


🔹 Contraindications

Absolute

Relative

Patient refusal

Severe anxiety or psychiatric illness

Age < 10 years (cooperation issue)

High risk of seizures

Inability to cooperate or communicate

Severe OSA

Language barrier (without interpreter)

Increased ICP or midline shift



🔹 Anesthetic Techniques

Three main techniques are used:

1. Asleep–Awake–Asleep (AAA)

  • GA for craniotomy → wake patient for mapping → re-anesthetize for closure
  • Advantage: Comfort during painful steps
  • Disadvantage: Risk of coughing/movement during emergence

2. Awake–Awake–Awake (AAA)

  • Entire procedure under sedation and local anesthesia
  • Advantage: Stable neuro exam, no emergence required
  • Disadvantage: Requires exceptional patient cooperation

3. Monitored Anesthesia Care (MAC)

  • Titrated sedation throughout (e.g., dexmedetomidine, remifentanil)


🔹 Preoperative Preparation

  • Detailed patient counseling: role during surgery, expectations
  • Psychological screening: anxiety, cooperation
  • Scalp block planned for intra-op analgesia
  • Preoperative imaging: fMRI, DTI tractography for planning


🔹 Monitoring

Monitor

Purpose

Standard ASA monitors

ECG, NIBP, SpO₂, EtCO₂

BIS or EEG

Sedation depth

Capnography via nasal cannula

Sedation monitoring

Video recording of patient’s face/speech

Optional, for team analysis

Neuromonitoring

Motor evoked potentials (MEP), electrocorticography (ECoG)



🔹 Scalp Block Technique

  • Blocks used: Supraorbital, supratrochlear, auriculotemporal, zygomaticotemporal, greater & lesser occipital nerves
  • LA used: Bupivacaine 0.25% or Ropivacaine, often with epinephrine


🔹 Sedation Techniques

Agent

Benefits

Dexmedetomidine

Sedation + analgesia + minimal respiratory depression

Remifentanil

Short-acting, easily titratable

Propofol (low dose)

Sedation, but beware of apnea

Midazolam

Caution—may affect memory/speech testing


Aim = Cooperative sedation, not unconsciousness.


🔹 Intraoperative Management

🔸 Phases:

  1. Craniotomy Phase:
    • Sedation + scalp block
    • Patient breathing spontaneously
    • Close communication with surgical team
  1. Mapping Phase:
    • Patient fully awake
    • No sedatives administered
    • Real-time testing: motor (movement), speech (naming, counting)
  1. Closure Phase:
    • Sedation can be resumed
    • Continue monitoring vitals and airway


🔹 Speech & Motor Testing Techniques

  • Speech tasks: Naming objects, reading, counting
  • Motor: Movement of limbs or face on command
  • Neuropsychologist or trained technician helps conduct tests


🔹 Complications and Management

Complication

Management

Seizures

Stop stimulation, apply cold saline, benzodiazepines

Airway obstruction

Jaw thrust, NPA insertion, minimal sedation

Nausea/vomiting

Ondansetron, dexamethasone

Panic/anxiety

Reassurance, adjust sedation

Headache/pain

Scalp block, NSAIDs, fentanyl (low dose)

Brain swelling

Head up position, mannitol, hyperventilation

Desaturation

Supplemental O₂, repositioning, suctioning



🔍 Viva & Exam Pearls

  • Most critical skill in awake craniotomy?
    👉 Patient selection and communication
  • Preferred sedative?
    👉 Dexmedetomidine (minimal respiratory depression)
  • Which phase is most challenging?
    👉 Transition from asleep to awake (if used)
  • What if seizure occurs?
    👉 Cold saline irrigation first, then IV benzo
  • Why avoid benzodiazepines pre-op?
    👉 Interferes with neurocognitive testing



📚 References

  • Miller’s Anesthesia, 9th ed. – Chapter on Neurosurgical Anesthesia
  • Cottrell & Young’s Neuroanesthesia
  • BJA Education – Awake Craniotomy and Sedation
  • WFSA Tutorial: Anesthesia for Awake Craniotomy
  • StatPearls: Awake Craniotomy