Approach for Epiduroscopic Laser Neural Decompression in Case of the Sacral Canal Stenosis
A 32-year old male patient visited our institution with the chief complaint of pain in the right hip and the lower back which started after he had experienced a minor traffic accident ten months prior to his visit. The pain became severe when he bent his waist, and an paresthesia was found with a numbness going to the tip of the right middle toe. The physical examination showed a positive finding in the straight leg raising test (20 degree/60 degree). The lumbosacral plain film showed that the disc space between L4 and L5 was narrow. The patient had no particular history. The patient's pain was not relieved but continued even after a caudal epidural steroid injection as well as after interlaminar epidural steroid injections given at one week intervals. Because the magnetic resonance imaging (MRI) showed a central herniated lumbar disc between L4 and L5 and compression of the right L5 nerve root, we decided to perform ELND.\nThe patient was hospitalized one day before the operation, and provided written informed consent. He started fasting eight hours before the operation and showed nothing unusual in the preoperative blood test. On the day of the operation, cefazolin 1 g was intravenously injected one hour before the beginning of the operation for the purpose of preventing an operation related infection. The patient was put into the prone position on the surgical table after arriving at the operating room. The position was adjusted with a Wilson frame and a pillow at the abdomen so that lumbar flexion could be unfolded and the upper body could be a little bit higher than the lower body. Afterwards, a wide area around the sacral hiatus was disinfected with aseptic technique. Local anesthesia was performed in the region to be operated on with 1% mepivacaine. Under direct fluoroscopy guidance, an 18 G Tuohy epidural needle was inserted into the sacral hiatus through the epidural space, and a 0.8 mm guide wire was inserted through the Tuohy needle. Keeping the guide wire in position, the Tuohy needle was carefully removed. In the process of making a small incision on the skin with a No. 11 blade and inserting a dilator through the guide wire, an unexpected resistance was found with the access. Despite repeated attempts carried out several times, the insertion to the sacral canal failed. We stopped the operation temporarily and reviewed the lumbosacral MRI sagittal plane image. It was found in the image that the conjugate diameter of the top 1/3 of the S4 spinal canal was 3.40 mm, which was smaller than the 3.96 mm outer diameter of the dilator for the epiduroscopy introducer set used in the operation (4007 Epiduroscopy introducer set, Myelotec, USA), and smaller than the 3.89 mm outer diameter of the introducer sheath (). Therefore, we decided to perform a S4 laminotomy at the entrance of the narrowed sacral canal with a hiatus rasp () designed to widen the canal opening. After making an incision of about 2 cm on the skin and on the sacrococcygeal ligament, the rasp was inserted into the narrowed region expanding the narrow sacral canal space by applying repeated rotational force (). Then, the dilator was normally inserted, and the channel and the space leading to the epidural space were widened, and the procedure could be stably completed. The patient's symptoms improved, and he was discharged two days after the operation.