Acta Anaesthesiol Taiwan 2010;48(3):148-151 ©2010 Taiwan Society of Anesthesiologists CASE REPORT A 40-year-old woman without remarkable medical history received epidural anesthe- sia for uterine cervix conization. Six hours after the operation, cauda equina syndrome occurred. Magnetic resonance imaging of the spine revealed epidural fluid accumulation around L5, as well as L4/5 herniated intervertebral disc found incidentally. Surgical decompression was performed with H-reflex monitoring. Epidural injection could result in cystic accumulation complicated with cauda equina syndrome. Epidural Cyst With Cauda Equina Syndrome After Epidural Anesthesia King-Chuen Wu 1 , Yi-Ying Chiang 2 , Bih-Chern Lin 2 , Hung-Tai Su 3 , Kin-Shing Poon 2 , Mei-Ling Shen 3 , Rick Sai-Chuen Wu 2 * 1 Department of Anesthesia, Eda Hospital, Kaohsiung, Taiwan, R.O.C. 2 Department of Anesthesiology, China Medical University Hospital, Taichung, Taiwan, R.O.C. 3 Department of Anesthesia, Taichung Tzu Chi General Hospital, Taichung, Taiwan, R.O.C. Received: Dec 31, 2008 Revised: Dec 4, 2009 Accepted: Dec 9, 2009 KEY WORDS: anesthesia, epidural; cauda equina; nerve compression syndromes; H-reflex *Corresponding author. Department of Anesthesiology, China Medical University Hospital, 2, Yude Road, North District, Taichung 40447, Taiwan, R.O.C. E-mail: cyy_tw@yahoo.com.tw 1. Introduction The rate of neurological complications in neuraxial blockades is around 1/20,000-30,000. Cauda equina syndrome (CES) is the second most frequent neuro- logical complication of neuraxial blockades after spinal hematoma. 1 We present here a case of CES that resulted from cystic accumulation of injected epidural local anesthetics. 2. Case Report A 40-year-old woman without remarkable medical history was scheduled for uterus cervix conization under epidural anesthesia. She had never experi- enced low back pain or sciatica. Physical examination revealed no spinal abnormality and there were no contraindications to epidural anesthesia. After setting up standard monitoring, the patient was placed in the decubitus knee-chest position and premedicated with intravenous midazolam 2.5 mg. After disinfection, the skin at the area of needle entry was infiltrated with 3 mL of 2% lidocaine for needle puncture. A Perican epidural needle with Tuohy bevel (18G ˜ 3.25”; B. Braun Melsungen AG, Melsungen, Germany) was used to enter the L3/4 intervertebral space via a paramedian approach. The loss-of-resistance to air technique was used to signal correct entry into the epidural space. The bevel of the needle was turned to face caudally and the epidural catheter was advanced downward. As the catheter was advanced some 8 cm beyond the bevel, pain and paresthesia of the legs were elicited,