A 70 year old patient with benign prostatic hyperplasia underwent transuretheral resection of prostate under spinal anaesthesia. One hour later, he developed vomiting and altered sensorium. Which of the following is the most probable cause?

The patient in question is a classical case of water intoxication following transurethral resection of prostate . During transurethral resection of prostate continuous irrigation with sterile water is installed to keep the field of vision clear and not obscured by haemorrhage. The absorption of water into circulation at this time give rise to the syndrome of water intoxication characterised by hyponatremia, hemolysis, and congestive hea failure. Confusion and other cerebral events mimicking stroke are seen as well. The incidence of this condition has been reduced since the introduction of isotonic glycine for performing resections and the use of isotonic saline for postoperative irrigation. Treatment includes fluid restriction. Ref: Bailey and Love's Sho Practice of Surgery, 24th Edition, Pages 1378-1379.