One hour after transurethral resection of the prostate under spinal anaesthesia, a 68-year-old man becomes confused and bradycardic. Serum sodium is 121 mEq/L. He reports seeing coloured rings around lights. The MOST likely diagnosis is:

• A Cerebral venous sinus thrombosis
• B TURP syndrome from absorption of hypotonic irrigation fluid ✓
• C Hypoglycaemic encephalopathy
• D High spinal anaesthesia with brainstem involvement

Explanation

Absorption of large volumes of hypotonic irrigant through open prostatic venous sinuses causes dilutional hyponatraemia, hypo-osmolality and cerebral oedema, presenting with confusion, bradycardia, hypertension and nausea; visual disturbance with coloured halos is characteristic of glycine-containing irrigants and reflects transient retinal toxicity. High spinal produces hypotension with respiratory embarrassment rather than hyponatraemia, and cerebral venous thrombosis does not correct toward normal sodium physiology.

Reference: Morgan and Mikhail's Clinical Anesthesiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.