Transient neurological symptoms (TNS) following spinal anaesthesia occur most commonly after which agent and in which patient position?

• A Hyperbaric bupivacaine; lithotomy position
• B 2-chloroprocaine; lithotomy position
• C Tetracaine; supine position
• D 5% lidocaine; lithotomy position ✓

Explanation

Transient neurological symptoms (TNS) — postoperative buttock and leg pain without neurological deficit resolving within 72 hours — occur most commonly after intrathecal 5% lidocaine (hyperbaric). The incidence is 0.5–30% depending on concentration and position. The lithotomy position dramatically increases risk, possibly because neural stretching combined with high lidocaine concentrations in pooled areas causes focal neurotoxicity. Bupivacaine has a very low TNS rate; 2-chloroprocaine and tetracaine carry intermediate risk. Lowering the lidocaine concentration to 2% or using isobaric preparations reduces but does not eliminate TNS.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.