Inclusion Criteria:  Woman aged 18 years and over. Histologically proven ovarian carcinoma. Indication for laparotomy surgery with xyphopubic incision. Acceptance of epidural anesthesia. Pain score ≤ 3 (VAS or Numeric Verbal Scale). Free and informed consent. Patient affiliated with a French social security scheme in accordance with French law on research involving human participants.  Exclusion Criteria:  Heart rhythm disturbances. History of Cerebral Vascular Accident (CVA). History of epilepsy. Wearing a pacemaker. Receiving morphine treatment preoperatively. Medical contraindication to an epidural. Patient unable to follow and adhere to trial procedures for geographic, social or psychological reasons. Patient placed under guardianship or curatorship. Patient already included in the present study.