Awake craniotomy

Surgical approach

• Indications: resection/biopsy near eloquent cortex (language, motor, sensory, visual pathways), epilepsy focus surgery, deep brain stimulation lead placement (variant)
  • Goal: maximise resection while preserving function using awake testing and/or electrocortical stimulation
• Positioning: supine/lateral/park-bench; head fixed in Mayfield pins; limited access to airway once draped
  • Often pinned before incision; local infiltration at pin sites and incision line
• Scalp incision → craniotomy flap → dural opening
  • Cortical mapping with stimulation; patient performs tasks (naming, counting, reading, limb movement)
  • Resection with repeated testing; haemostasis; dural closure; bone flap replacement; scalp closure
• Key surgical stimuli: pinning, scalp incision, temporalis dissection, dural traction, cortical stimulation, irrigation, closure
  • Brain parenchyma is not pain sensitive; pain mainly from scalp, periosteum, muscle, dura

Anaesthetic management (overview)

• Type of anaesthesia: awake with sedation + regional scalp block; or asleep–awake–asleep (AAA) with GA for opening/closure and awake mapping phase
  • Choice depends on patient factors, lesion location, expected mapping duration, surgeon preference, and airway risk
• Airway: usually spontaneous ventilation; oxygen via nasal cannula/face mask; consider high-flow nasal oxygen; airway rescue equipment immediately available
  • ETT/SGA typically only if AAA (during asleep phases) or conversion to GA
• Duration: commonly 3–6 hours (variable; mapping can be prolonged)
  • Plan for fatigue, hypothermia, pressure areas, and prolonged immobility
• How painful: moderate without regional; can be well tolerated with scalp block + careful sedation; discomfort often from pins, incision, temporalis traction, neck/shoulder strain, anxiety
  • Dural manipulation may cause headache/nausea; cortical stimulation can provoke seizures
• Key anaesthetic goals: cooperative patient for testing, immobility when required, stable haemodynamics/ICP, avoid respiratory depression/hypercapnia, rapid titratable sedation, seizure readiness, airway rescue plan
  • Maintain cerebral perfusion pressure (CPP) and avoid hypoxia/hypercapnia (↑CBF/ICP) and hypotension (↓CPP)

Indications and patient selection

• Indications: lesions adjacent to eloquent cortex; need for real-time functional testing; epilepsy surgery requiring mapping; sometimes DBS (awake component differs)
• Contraindications (relative): inability to cooperate (severe anxiety, confusion, dementia), severe OSA/obesity with high airway risk, uncontrolled reflux/aspiration risk, severe cough, inability to lie flat, severe dysphasia precluding testing, movement disorders, raised ICP with reduced compliance, severe cardiorespiratory instability
• Pre-op counselling: explain phases, need to stay still, potential discomfort, seizure possibility, how communication will work, and conversion to GA possibility

Pre-operative assessment and optimisation

• Neurological baseline: language, motor deficits, seizures frequency; document pre-op function for intra-op comparison
• Seizure management: continue antiepileptics; check adherence; consider pre-op levels only if clinically indicated; avoid precipitants (sleep deprivation, hypoglycaemia)
• Steroids: often on dexamethasone for oedema; consider glucose control and infection risk
• Airway assessment: anticipate limited access once pinned/draped; plan rescue strategy (who will undrape/unpin; where equipment is)
• PONV risk: high; plan multimodal prophylaxis

Technique options

• Awake throughout (monitored anaesthesia care): scalp block + titrated sedation/analgesia; avoids airway instrumentation; continuous ability to test
  • Requires excellent regional technique and careful sedation to avoid hypoventilation/obstruction
• Asleep–awake–asleep (AAA): GA for pinning/opening; wake for mapping/resection; GA again for closure
  • Airway: usually SGA or ETT during asleep phases; remove for awake phase (or lighten with SGA in situ in selected centres, but can interfere with speech testing)
  • Pros: comfort during most stimulating parts; cons: airway manipulation, emergence agitation, time, risk of coughing/straining/ICP surges
• Choice of sedatives: propofol and remifentanil (titrated) or dexmedetomidine-based; avoid long-acting agents that delay testing
  • Dexmedetomidine: cooperative sedation with minimal respiratory depression; can cause bradycardia/hypotension
  • Propofol/remifentanil: very titratable but higher risk of apnoea/obstruction; stop/low dose during mapping

Regional anaesthesia: scalp block and infiltration

• Scalp block targets: supraorbital, supratrochlear, zygomaticotemporal, auriculotemporal, greater occipital, lesser occipital nerves (bilateral as needed)
• Local infiltration: pin sites, incision line, temporalis muscle, periosteum; surgeon often infiltrates dura (variable efficacy)
• Local anaesthetic safety: calculate maximum dose (consider mixture and patient weight); use incremental aspiration; consider adrenaline-containing solutions for scalp (vascular) to reduce bleeding and prolong block
  • Be prepared for LAST: intralipid immediately available; team brief

Monitoring and access

• Standard monitoring + invasive arterial line (beat-to-beat BP, blood gases if needed); capnography via nasal cannula; temperature; urinary catheter for long cases
• IV access: at least 1–2 good cannulae; consider large-bore if expected blood loss; ensure lines are accessible after draping
• Adjuncts: BIS/processed EEG may help titrate sedation; neurophysiology monitoring may be used (MEP/SSEP) depending on case

Intraoperative conduct (practical plan)

• Team brief: phases of case; when patient must be interactive; seizure plan; airway rescue plan; who can rapidly remove drapes/unpin; acceptable BP/CO2 targets
• Positioning: meticulous padding; avoid neck flexion/rotation causing venous obstruction/airway compromise; ensure patient comfort before pinning
• Sedation strategy: aim for calm, cooperative (RASS around 0 to -2) during non-testing; lighten/stop sedatives during mapping; avoid oversedation
  • Analgesia: scalp block + small opioid boluses if needed; avoid large opioid doses before mapping
• Ventilation: maintain spontaneous ventilation; avoid hypercapnia (↑CBF/ICP) and hypoventilation; provide supplemental O2; consider ABG if concerns
• Haemodynamics: avoid hypertension (bleeding, oedema) and hypotension (↓CPP). Treat pain/anxiety first; then titrate vasoactive drugs as needed
  • Common agents: metaraminol/phenylephrine for hypotension; labetalol/esmolol for tachycardia/hypertension; avoid excessive sedation to treat BP
• Fluids: aim euvolaemia; avoid hypotonic fluids; consider balanced crystalloids; manage glucose (steroids) and sodium (risk of SIADH/cerebral salt wasting is more post-op)
• PONV: multimodal (e.g., dexamethasone if appropriate, ondansetron, droperidol); minimise opioids; treat early to avoid raised ICP and movement

Seizures during awake craniotomy

• Triggers: cortical stimulation, local anaesthetic toxicity (rare), hypoglycaemia, sleep deprivation, withdrawal of antiepileptics
• Immediate management: stop stimulation; call for cold saline irrigation to cortex; protect airway and patient from injury; ensure oxygenation and ventilation
• Drug treatment (if prolonged/generalised): small IV boluses of propofol or midazolam; consider levetiracetam/phenytoin per local practice; be ready to convert to GA if airway/ventilation compromised
  • Balance seizure termination vs preserving ability to test; use minimal effective doses

Airway obstruction and conversion to GA

• Risk factors: oversedation, OSA/obesity, head/neck position, secretions, opioid use
• Early management: verbal/tactile stimulation, reduce sedatives, jaw thrust, airway adjuncts (nasopharyngeal/oropharyngeal), reposition head/neck if possible, HFNO/CPAP if feasible
• Conversion to GA: pre-agreed plan; stop surgery; undrape as needed; consider SGA as quickest rescue; ETT if aspiration risk/need controlled ventilation; anticipate difficult access with pins and limited mouth opening
  • Have videolaryngoscope, bougie, suction, and emergency front-of-neck access kit immediately available

Complications

• Intra-op: seizures, airway obstruction/apnoea, aspiration, agitation/panic, nausea/vomiting, pain, hypertension/hypotension, venous air embolism (rare but possible), bleeding, LAST
• Neurosurgical: brain swelling, intracranial haemorrhage, new neurological deficit, CSF leak, infection
• Post-op: PONV, headache, delirium, seizures, airway compromise (sedation/opioids), hyponatraemia, steroid hyperglycaemia

Post-operative care

• Destination: PACU with neuro obs; consider HDU/ICU depending on comorbidity, intra-op events, and extent of surgery
• Analgesia: paracetamol + NSAID if appropriate; minimise opioids; treat scalp pain; consider local infiltration top-ups by surgeon
• Antiemetics: continue prophylaxis; low threshold to treat vomiting (risk of raised ICP and wound issues)
• Seizure prophylaxis: continue antiepileptics; monitor; manage triggers (sleep, glucose, electrolytes)