This study evaluates the influence of premedication on cognitive functions in patients
undergoing transurethral resection of bladder tumor under spinal anesthesia. The aims of
premedication are anxiolysis, analgesia and the reduction of perioperative risk among the
patients with comorbidities. The patients will be randomly allocated to receive premedication
either with opioid solely or with benzodiazepine combined with opioid. The anesthetic
technique is standardized.