Cauda equina syndrome after incidental total spinal anesthesia with 2% lidocaine

A 77 year-old male presented for a right popliteal distal vein bypass graft procedure with continuous epidural anesthesia and light general endotracheal anesthesia. After the uneventful placement of the epidural needle and catheter at the L2-L3 interspace, fentanyl 150 microg and a total of 72 ml of preservative-free 2% lidocaine with epinephrine was continually injected through the epidural catheter for the duration of the more than 5 hour procedure. At the end of the procedure, it was noted that the patient had developed total spinal anesthesia, and his pupils were fixed and dilated. Further examination confirmed that the catheter tip was placed in the subarachnoid space. The patient was unable to turn or sit up by himself for over 1 month. Over a 12-month period, he improved to walking with a quad cane, but he required self-catheterization. Although numerous factors were considered, neurotoxicity of 2% lidocaine solution has been discussed as the potential cause. We were unable to find any other factors that could have caused the cauda equina syndrome.