Cauda equina syndrome after spinal anesthesia: A case report.

A 72-year-old man undergoing emergency arthroscopic irrigation and debridement of the left knee joint due to pyogenic arthritis developed cauda equina syndrome after spinal anesthesia with 0.5% hyperbaric tetracaine mixed with epinephrine. Epinephrine was added to local anesthetic to prolong the duration and to increase the quality of spinal anesthesia. There was no paresthesia on needle placement. We injected anesthetics twice because the first subarachnoid injection failed. The patient experienced impaired sensation in the perineal region and alterations in bowel and urinary habits. Magnetic resonance imaging revealed spondylolisthesis and disc protrusion (L4-5), with spinal stenosis (L5-S1), but did not show suspicious lesions such as hematoma and abscess. We suggest the causative factors are temporary neural compression due to his spinal diseases and spinal cord ischemia due to decreased spinal blood flow because of epinephrine. We also cannot rule out the tetracaine neurotoxicity.