Awake craniotomy for a glioma near the motor strip32-year-old woman, 70 kg, for awake craniotomy with motor mapping of a low-grade glioma beside the right motor strip

The patient

The examiner asks

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1. Consider

   What are your concerns?

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   • A 32-year-old with a glioma beside the motor strip, for awake craniotomy with motor mapping. Patient
   • Anxiety predicts failed sedation, so building rapport comes first.
   • OSA and BMI 31 raise her risk of obstruction once sedated. Airway
   • Head pinned and draped: my access to her airway will be poor.
   • Her focal seizures may be provoked by stimulation during mapping. Disease

2. Prepare

   How do you select and prepare her?

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   • Rapport in clinic: what she'll hear, feel and do at each stage. Patient
   • She agrees, shares our language and can cooperate, so she's a candidate.
   • Options: sedation alone, or asleep-awake-asleep using an LMA; no technique has been shown better. Disease
   • With her OSA, I favour an LMA for the asleep phases. Airway
   • Levetiracetam continues; I ask her to describe her aura so we spot seizures early. Disease
   • LMA, videolaryngoscope, cold saline and propofol ready before pinning. Crisis

3. Plan

   How will you conduct it?

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   • Scalp block: six nerves on each side and the pin sites, mixing long- and short-acting local. Disease
   • I keep a running total: bupivacaine 2 mg/kg, lidocaine with adrenaline 7 mg/kg.
   • Sedation: propofol plus remifentanil 0.02–0.05 mcg/kg/min; dexmedetomidine 0.2 mcg/kg/h is the alternative.
   • During testing, dexmedetomidine 0.1–0.2 mcg/kg/h keeps her responsive.
   • Capnography throughout, confirming airway patency breath by breath. Airway
   • Ondansetron and dexamethasone routinely; vomiting under drapes is dangerous. After surgery
   • Warm, padded and comfortable, with her face visible for testing. Patient

4. Crisis

   In the sedated phase her capnograph trace shrinks; she snores, then goes silent, and her SpO2 drops to 88% as you watch. What do you do?

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   • Obstruction with hypoventilation; hypercapnia will swell her brain. (Crisis)
   • Reduce sedation, jaw thrust, 100% oxygen.
   • Tell the surgeon to pause.
   • Not improving: insert the LMA under the drapes and ventilate.
   • Once she's clear, restart sedation at a lower rate.

5. Crisis

   During mapping her left arm starts jerking; afterwards she's agitated and won't keep still. What do you do?

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   • Stimulation stops and the surgeon pours cold saline onto the cortex. (Crisis)
   • Still fitting: propofol 0.5–1 mg/kg increments, once it clearly isn't stopping.
   • Protect her: hold the limb, watch her airway and the pinned head.
   • If she can't cooperate, convert to general anaesthesia.
   • LMA first under the drapes; it's the quickest airway here.
   • Few hands in this setting: call a second anaesthetist early.