We recently reported several cases consistent with transient radicular irritation after spinal anesthesia with hyperbaric 5% lidocaine. The present prospective, blind, nonrandomized study was performed to determine the incidence of these transient neurologic symptoms and to identify factors that might be associated with their occurrence. We studied 270 patients scheduled for gynecologic or obstetric procedures under spinal anesthesia. For spinal anesthesia, either 5% lidocaine in 7.5% glucose or 0.5% bupivacaine in 8.5% glucose was used. Patients were evaluated on postoperative day 3 by a quality assurance nurse who was unaware of the drug given or details of the anesthetic technique. Transient neurologic symptoms were observed in 37% of patients receiving 5% lidocaine, whereas only one patient receiving 0.5% bupivacaine had transient hypesthesia of the lateral aspect of the right foot. These results suggest that symptoms were the result of a specific drug effect. However, because of the limitations of the study one cannot conclude that lidocaine per se was the cause.

Hampl, Schneider, Ummenhofer, Drewe, , , , , (1995). Transient neurologic symptoms after spinal anesthesia. Anesthesia and analgesia, 1995 Dec;81(6):1148-53. https://www.ncbi.nlm.nih.gov/pubmed/7486096