THE EFFECTS OF INTRATHECAL NEOSTIGMINE ON SOMATIC AND VISCERAL PAIN -IMPROVEMENT BY ASSOCIATION WITH A PERIPHERAL ANTICHOLINERGIC

This study was designed to qualitatively evaluate the analgesic action s of intrathecal neostigmine alone and with intravenous (IV) N-butyl-s copolamine on somatic and visceral pain. Twenty-seven patients schedul ed for both tubal ligation and vaginoplasty were divided into three gr oups. Patients received a standard anesthetic with thiopental, atracur ium, and N2O/O-2/enflurane. N-butyl-scopolamine, 20 mg, or saline was administered as a 2-mL IV bolus 20 min before the end of the surgical procedure. The control group (CG) received spinal and IV saline; the n eostigmine group (NG), spinal neostigmine and N saline; and the neosti gmine-N-butyl-scopolamine group (NSG), spinal neostigmine and IV N-but yl-scopolamine. Postoperatively, patients assessed their pain on a 10- cm visual analog scale (VAS). The CG had both visceral and somatic pai n at the first 30-min assessment, and all patients requested morphine. Patients from the NG had only visceral pain from the first assessment ; however, they had lower VAS scores (P = 0.026) and requested less mo rphine (P = 0.037). Patients from the NSG were pain free during all as sessment times (P < 0.0001). Neostigmine was more effective for somati c pain than visceral pain. N-butyl scopolamine administration acted pe ripherally as an effective complement for treatment of visceral pain, reflecting an association between central cholinergic effects and peri pheral anticholinergic effects in the treatment of visceral postoperat ive pain.