A 34-year-old man sustained complete traumatic transection of the spinal cord at T6 ten days ago. He now requires emergency surgery. Succinylcholine should be avoided because:

• A It causes severe bradycardia via exaggerated baroreceptor responses below the lesion
• B It precipitates autonomic dysreflexia through splanchnic vasoconstriction
• C Spinal shock abolishes the response to succinylcholine entirely
• D Denervation upregulates extrajunctional nicotinic receptors, causing massive potassium efflux ✓

Explanation

After denervation, extrajunctional fetal-type nicotinic receptors proliferate across the muscle membrane. Succinylcholine depolarises all of these receptors, releasing large amounts of potassium and risking fatal hyperkalaemic arrest. The risk begins around 48 to 72 hours after injury, peaks in the first weeks, and persists for months. Autonomic dysreflexia is triggered by noxious stimuli below the lesion, not by succinylcholine.

Reference: Miller's Anesthesia, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.