Transient radicular irritation after spinal anesthesia induced with hyperbaric solutions of cerebrospinal fluid-diluted lidocaine 50 mg/ml or mepivacaine 40 mg/ml or bupivacaine 5 mg/ml

Background: Transient radicular irritation (TRI) is common after spinal anesthesia induced with hyperbaric lidocaine 50 mg/ml. The purpose of this study was to determine the incidence of TRI after spinal anesthesia with hyperbaric lidocaine 50 mg/mi diluted with cerebrospinal fluid (CSF) 1:1 and hyperbaric mepivacaine 40 mg/ml and hyperbaric bupivacaine 5 mg/ml. Methods: Ninety ASA class I-TV patients undergoing mostly brief urological procedures under spinal anesthesia were randomly allocated to receive either hyperbaric lidocaine 50 mg/ mi diluted with CSF 1:1 (Group L), hyperbaric mepivacaine 40 mg/ml (Group M) or hyperbaric bupivacaine 5 mg/ml (Group B). Characteristics of the patients and details of the surgical procedures and spinal anesthesias were similar in all groups except for the intensity of motor block. The patients were evaluated on the first postoperative day by an anesthesiologist who did not know which spinal anesthetic agent had been used. Results: Six patients (20%) in Group L, 11 patients (37%) in Group M and none (0%) in Group B experienced pain in the legs and/or back (TRI) after spinal anesthesia. Conclusion: TRI is frequent after spinal anesthesia induced with hyperbaric lidocaine 50 mg/ml diluted with CSF 1:1. The incidence of TRI after hyperbaric mepivacaine 40 mg/ml is of the same magnitude. TRI could not be observed after bupivacaine spinal anesthesia.