Toxicity of spinal local anaesthetics

Recent reports of severe neurological injury after spinal anaesthesia have generated concerns about the neurotoxic potential of local anaesthetics and, in particular, of lignocaine. Further, there is an increasing body of evidence indicating that transient neurological symptoms commonly occur after uneventful lignocaine spinal anaesthesia but not after bupivacaine. Results from an epidemiological study suggest that patient positioning and outpatient status are major co-factors. Neither the dose nor the concentration of lignocaine appear to reduce the risk for transient neurological symptoms. Available data on alternative short-acting local anaesthetics with respect to transient neurological symptoms are limited and conflicting. Experimental data provide further information on factors contributing to local anaesthetic induced neurotoxicity: adrenaline significantly increases the neurotoxic effects of lignocaine in vivo, whereas the addition of glucose does not.