Neurotoxicity of intrathecal local anaesthetics and transient neurological symptoms

Local anaesthetics have been placed in the intrathecal space for approximately 100 years. Currently used intrathecal local anaesthetics appear to be relatively benign on the basis of the low incidence of permanent neurological deficits. In large retrospective surveys of 4000-10 000 patients, the incidence of persistent neurological sequelae after subarachnoid anaesthesia varies between 0.01 and 0.7%. Since its introduction in 1948, hyperbaric 5% lidocaine has been used for millions of spinal anaesthetics. The predictable onset and limited duration of action have made lidocaine one of the most popular spinal anaesthetics currently available. Concern about the use of spinal lidocaine began in 1991 with published reports of cauda equina syndrome after continuous spinal anaesthesia. In 1993, Schneider published a case report of four patients undergoing spinal anaesthesia who postoperatively experienced aching and pain in the buttocks and lower extremities. This chapter reviews the neurotoxicity of spinal local anaesthetics, as well as the incidence, possible aetiology, and treatment of transient neurological symptoms after lidocaine spinal anaesthesia.