Motor evoked potential monitoring is planned during resection of a cervical intramedullary spinal cord tumour. Which anaesthetic strategy BEST preserves transcranial motor evoked potential amplitudes?

• A Sevoflurane 1.5 MAC with full neuromuscular blockade
• B Propofol and remifentanil total intravenous anaesthesia with neuromuscular blockade limited to one or two twitches on train-of-four ✓
• C Nitrous oxide and isoflurane with no neuromuscular blockade
• D High-dose opioid anaesthesia with complete neuromuscular paralysis

Explanation

Transcranial electrical motor evoked potentials are exquisitely sensitive to volatile agents and nitrous oxide, which suppress the anterior horn cell response and abolish amplitudes at clinically useful concentrations. A propofol and remifentanil total intravenous technique preserves responses best. Complete neuromuscular paralysis eliminates the muscle response entirely, so relaxation must be partial, typically allowing one or two twitches on train-of-four monitoring throughout recording.

Reference: Miller's Anesthesia, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.