| Selective endoscopic discectomy refers to a technique developed by Tony Yeung, MD of Phoenix in which arthroscopic surgery is applied to the spine with a specific series of procedures performed through the endoscope. These procedures have enhanced the safety of the technique which has evolved from the work of Parvitz Kambin, John Chiu, and Martin Savitz, who were pioneers in the field of endoscopic spine surgery. Whereas now there are several other "minimally invasive" techniques such as the Medtronics METRX system, selective endoscopic discectomy (SED) provides access to the spine using a much smaller cannula with less tissue damage to the muscles, ligaments, and bones compared to the later quasi-minimally invasive techniques. SED has been used since approximately 1990 with tens of thousands of applications world wide, but in the US the technique has not been embraced by surgeons due to the unusual equipment used which is unfamiliar to many surgeons, the unorthodox approach to the spine at a 45-50 degree angle instead of straight into the back, and the anatomy seen which is quite unfamiliar to surgeons who have not used the technique. There are only a handful of surgeons in the US performing SED. WHAT IS SED? SED is an acronym for a procedure originally designed to remove spinal herniated disc material. SED is Selective because the angle of the scope placed into the spine permits access to the disc, the epidural space, the facet, the neuroforamen, the nerve roots, and scar tissue. Changing the angle slightly permits access to each of the above. Endoscopic refers to the use of an endoscope, in particular in this case, an endoscope connected to a video camera. The scope has working channels through which is passed long thin instruments such as lasers, surgical forceps, burrs, drills, and electrocautery probes in addition to several other devices. The passage of these devices directly through the scope permits direct visualization of the field of the operation so there is no guesswork. Discectomy refers to removal of disc material through the endoscope. The herniated disc may be removed intact through the endoscope. Of course, the technique has expanded far beyond the original discectomy and now can be applied to carving away bone which is pressing on sensitive nerve roots, removal of scar tissue, removal of thickened ligaments, and evaluation of other pathologies in the spine. HOW IS SED DIFFERENT THAN TRADITIONAL DISCECTOMY? A traditional surgical discectomy, lumbar microdiscectomy or laminectomy with discectomy both use incisions which split muscles of the spine or remove their insertion tendons from the bone, use retractors to open up the space in the split muscle (retractors can cause long term injury to these important spinal muscles), remove bone from the spine in order to access the disc herniation, cause bleeding into the epidural space which may lead to excessive scar tissue formation, and require retracting the nerve roots which can damage nerves. SED does none of these. Studies show recovery time is faster with SED than with traditional surgery. SED is performed with sedation and special anesthetic techniques permitting it to be an outpatient surgery while most traditional discectomies require a general anesthetic and hospital stay. HOW IS A SED PERFORMED? The patient lies face down on a padded operating table, and has sedation administered by an anesthesiologist. Sterile surgical skin prep is used followed by surgical drapes placed over the back. A fluoroscope is used for the procedure and is brought into place over the back. Next a thin needle is inserted into the disc at a 45 degree angle to the spine and injected with a special blue dye which stains the degenerative and herniated disc blue leaving the normal disc white. A small wire is passed through the needle, the needle is removed, and a dilator is passed over the wire into the disc. A 6mm diameter working cannula (1/4" diameter) is placed over the dilator and into the disc. The dilator is removed leaving a channel for the endoscope through the cannula directly into the disc. Once the endoscope is advanced into the disc, herniated disc material is removed with long grasping tools, side firing Holmium YAG lasers, automated mechanical debridement, etc. Once the disc fragment is removed, the endoscope and cannula are removed, a single stitch or band-aid is used on the wound, and the patient goes home usually within an hour. WHAT IS THE SUCCESS RATE FOR SED? While patient selection is critically important just as in other disc surgeries, success rates in studies performed for disc herniation with predominately leg pain are as follows: 88% Success Rate 169 patients Clin Orthop 1998 Feb;(347):150-67 Arthroscopic microdiscectomy and selective fragmentectomy. Kambin P 89% Success Rate 600 patients Mt Sinai J Med 2000 Sep;67(4):283-7 Arthroscopic microdiscectomy: an alternative to open disc surgery. 86.4% Success Rate 500 patients Mt Sinai J Med 2000 Sep;67(4):327-32 The evolution of percutaneous spinal endoscopy and discectomy: state of the art. Yeung AT. Squaw Peak Surgical Facility, Phoenix, AZ, USA 85% Success Rate 49 patients Far Lateral HNP J Neurosurg 2001 Apr;94(2 Suppl):216-20 Transforaminal percutaneous endoscopic discectomy in the treatment of far-lateral and foraminal lumbar disc herniations. Lew SM, Mehalic TF, Fagone KL.. For patients with diffuse disc bulges with significant back pain but little leg pain, the success rates are as follows: 83% Good-Excellent Outcome South Med J 2000 Sep;93(9):885-90 Marks RA Transcutaneous lumbar diskectomy for internal disk derangement: a new indication. 81% Good-Excellent Outcome World Congress of Minimally Invasive Spine Surgery Dec 2000 Anthony Yeung, MD COMPLICATIONS OF SED SED complications are potentially the same as other surgical procedures of the spine. Bleeding (superficial skin, subcutaneous hematoma, epidural hematoma, psoas muscle or multifidus hematoma), infection (superficial, subcutaneous, epidural abscess, meningitis), scar tissue formation (including peridural fibrosis, perineural fibrosis, arachnoiditis), dural tear with spinal headache, inadequate decompression, nerve injury or at the level of L2 or above cord injury, neuritis (enhanced transient extremity pain), failure to relieve pain, need for further surgery, etc. If the disc problem is amenable to a strictly intradiscal approach (targeting only the disc), then the risks of several of the above complications (epidural abscess, epidural scar, epidural bleeding, arachnoiditis, nerve injury) are probably much less than traditional surgery since the epidural space is completely avoided. This appears to be one of the greatest advantages of SED. TRAINING IN SED: Currently training is available only by special arrangement for this extremely advanced procedure. There are only approximately 5-10 pain management surgeons in the US performing this technique and approximately 20 orthopedic spine surgeons trained in the technique. My training in SED began in Phoenix and was expanded in Zurich Switzerland and in Seoul Korea. The technique is not taught in any residency program in the US due to the highly advanced equipment and skills needed to perform the technique. |
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| Selective Endoscopic Discectomy |
