This study aims to evaluate the possible effect of melatonin on prevention of cognitive dysfunction in the postoperative period of elderly patients undergoing transurethral resection of the prostate (TURP) under spinal anesthesia

TURP is the most common surgical procedure performed on male patients over 60 years of age to treat benign prostatic hyperplasia.

One of the concerns, since it compromises the quality of life, is postoperative cognitive dysfunction. It can be due to TURP Syndrome or to other causes, like changing the routine and circadian rhythm for patients with more susceptibility.

The investigators postulate that melatonin premedication and use during the perioperative period could avoid cognitive impairment in patients undergoing TURP surgery that didn't develop major complications, like TURP Syndrome.

Since anesthestic technic could also influence the outcome of POCD, only patients undergoing spinal anesthesia were included in the study,

Inclusion Criteria:

patients over 60 years who underwent elective surgery for transurethral prostate ressection under spinal anesthesia.

MME > 18 (for those who had less than 4 years of formal education ) or MME > 23 (for those with 4 or more years of formal education)

Exclusion Criteria:

MME < 18 (for those who had less than 4 years of formal eduaction) or 23 (for those with 4 years or more of formal eduacation); History of cancer, brain disease, seizure, Parkinson, dementia, hallucination or any disorder that affects cognition before the surgery.

Lack of proficiency in portuguese mild or severe hearing loss or blindness.

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