The working cannula should at all times be situated lateral to the medial pedicle line as this represents the lateral extent of the dural sac and traversing nerve root, any medial impingement by the edge of the cannula risks dural laceration.
Decompression should be commenced by first improving visualization of the offending structure and thus being able to assess the relevant pathology in terms of neural compression. Often this may mean resection of overlying and more superficial structures in order to achieve better visualization and achieve more working space.
Bone resection may be achieved by use of endoscopic shavers or lasers, Bleeding may be encountered in the form of epidural venous plexus, this may be addressed by radiofrequency coagulation or laser coagulation.
The disc should now be easily visible as it has been stained by the previously injected indigo carmine dye. Disc material that is dorsal to the vertebral body and PLL is removed, additional removal of any loose fragments or complete fragments will depend on operator preference.
Controversy exists in the amount of disc excision, as in microdiscectomy, the question of how much nucleus pulposus to excise remains. Many operators advocate to try to preserve disc height and stability and excise the herniated portion and hope that the remaining defect will scar and seal off, others faced with the risk or experience of reherniation may advocate to do more and remove the remained of any “unstable” nuclear material. In any case after the discectomy the remaining annulus and posterolateral aspect of the PLL, facets and other structures that may come into contact with the decompressed nerve root should be denervated by radiofrequency ablation or by laser coagulation. This will minimize the onset of or recurrence of discogenic or other forms of pain after the procedure.
The term minimally invasive surgery encompasses many procedures that achieve their result through a smaller access portal. Whereas in the more traditional approaches such as microdiscectomy are modifications of open laminotomy and other transcanal procedures, endoscopic spine surgery through a posterolateral extracanal approach is a newer and truly canal sparing procedure.
This technique has been made available through parallel development keeping pace with technological advances in fiber-optics materials, instrument and imaging technology.
As new techniques develop, new learning curves will follow. Surgeons used to the open and minimally invasive translaminar approaches will have to familiarize themselves with anatomy from the “other side of the fence”. An intricate knowledge of extraforaminal anatomy and approach together with mastery of new techniques in handing of endoscopic instruments and 3D coordination will result.
1. Yasargil MG (1977) Microsurgical operations for herniated lumbar disc. Adv Neurosurg 4:81-82
2. Hijikata S, Yamagishi M, Nakayama T, et al ( 1975) Percutaneous discectomy: a new treatment method for lumbar disc herniation. J Toden Hosp 5:5-13
3. Kambin P, Gellman H ( 1983) Percutanseous lateral discectomy of the lumbar spine: a preliminary report. Clin Orthop 174:127-132
4. Onik G, Helms C, Ginsburg L, et al (1985) Percutaneous lumbar discectomy using a new aspiration probe. AJR Am J Roentgenol 144: 1137-1140
5. Kambin P (1991) Arthroscopic microdiscectomy. Semin Orthop 6:97-108
6. Kambin P (1991) Arthroscopic microdiscectomy: laser nucleolysis. Philadelphia Med 87: 548-549
7. Kambin P (1992) Arthroscopic microdiscectomy: Arthroscopy 8: 287-295
8. Kambin P (1996) Arthroscopic microdiscectomy. In: Frymoyer J, Ducker T, Hadler N, Kostuik J, Weinstein J, Whitecloud T III (eds) The adult spine principles and practice, 2nd edn. Raven, New York