Transient radicular irritation after spinal anaesthesia with hyperbaric 5% lignocaine

We have studied prospectively 600 patients who had spinal anaesthesia for minor surgery, to evaluate the incidence of transient radicular irritation after the block. The anaesthetic agent (hyperbaric 5% lignocaine, hyperbaric 0.5% bupivacaine or plain 0.5% bupivacaine) was chosen according to the anticipated duration of surgery. We obtained information after operation from 537 patients (282 by telephone, 255 by letter). Ten percent of patients anaesthetized with hyperbaric 5% lignocaine (27 patients) had transient bilateral radiating pain in the lower extremities, buttocks, or both. Typically the pain started within 24 h after spinal anaesthesia, lasted less than 2 days and was described as mild. Lignocaine was the only variable that correlated with this pain. Two patients complained of symptoms after hyperbaric 0.5% bupivacaine but these were atypical compared with pain after lignocaine. None of the patients anaesthetized with plain bupivacaine had similar complaints. We conclude that the use of 5% hyperbaric lignocaine for spinal anaesthesia should be reconsidered.