Shao-Keh Hsu 徐少克 Minimal Invasive Spinal Center脊椎微创中心 Tungs’ Taichung MetroHabor Hospital, Taichung，Taiwan，China台中童综合医院

Endoscopic spinal surgery, at a crossroads similar to that of arthroscopic knee surgery in the 1970s, is poised to serve the same role. Percutaneous endoscopic discectomy techniques in spine surgery have evolved rapidly in the past several years. Kambin et al first introduced it in the United States in 1973 and the working triangle of nerve root was described and illustrated by Kambin in 1991. Since 1997, Anthony Yeung spine scope system (YESS) improve in scope design, access cannula, instrumentation, and adjunctive therapy which provide endoscopic procedures more wider spectrum including routine spinal probing, tissue resection, tissue modulation, and ablation. These advancements have enhanced the surgeon’s ability to diagnose and treat discogenic pain and take on the full spectrum of disc herniations, including extruded and sequestered fragments.
( I ) Comparison between Endoscopic Surgery and Conventional Surgery
The main purposes of surgical treatment for lumbar disc herniations are to decompress, to reduce surgical damages and to reduce postoperative complications. Conventional lumbar discectomy uses posterior approaches, which demand muscle dissection and bone removal to enter the spinal canal. The most common problems are postoperative complications such as urine retention and decreased lung function caused by general anesthesia. More than 10% patients showed clinical symptoms of epidural scaring [1-5], and postoperative neural adhesion is an even more common challenge in revision lumbar spine surgery. The rate of recurrent disc herniation following conventional discectomy is approximately 5%-11%. Under the interference of the epidural scar tissue, revision surgery generally requires to outwardly expend the working area to minimize the potential irritation to the nerve root and to avoid damaging the nerve root and the epidural sac. The outward expansion inevitably increases the chance of damaging the posterior spinal column, as well as unilateral, bilateral or multiple levels of the spinal
joints, leading to spine destabilization [6-14]. Percutaneous foraminal endoscopic surgery has the following advantages: (1) no need or general anesthesia; (2) lateral access that does not affect the nerve root and rarely causes nerve damage; (3) low infection rate; (4) no damage to the ligament and spinal structure, low formation of scar tissue, and reoperation does not have to overcome the difficulties caused by scar tissue; (5) fast recovery; (6) low recurrent rate [15-21]. Staying in a conscious state during the procedure, patients can communicate with the surgeon, which can provide the surgeon more and wider treatment options. The recurrent rate of endoscopic lumbar spine surgery around 3%-8% .
(II)Recurrent , Foraminal and Extraforaminal lumbar disc herniations :
For recurrent lumbar disc herniations, posteriorlateral access, instead of the original surgical access, was applied to directly treat the source of the recurrence. Meanwhile, chemicals causing pain were frequently washed away. The procedures are relatively simple with no damage to the posterior muscle and bone, no lumbar spine destabilization, and on need of planting an internal cage or fusion [22]. Although the rate of satisfactory results is only 76%, compared with conventional revision surgery percutaneous endoscopic lumbar spine surgery is relatively simple and is associated with fewer complications. And even if patients are not satisfied with the results of their endoscopic surgery, they can still undergo conventional open surgery. Percutaneous endoscopic intervertebral foraminal surgery is an option between surgical and nonsurgical treatments. The main reasons that patients suffering recurrent lumbar disc herniations were not satisfied with the results of percutaneous endoscopic foraminal procedures include: (1) patients originally had epidural pachymeningitis