The history of open surgical treatment of herniated lumbar discs started over sixty years ago. Williams described Microlumbar Discectomy in 1978 . This is a small incision technique using an external overhead microscope. It is, of course, a small open operation which requires a posterior midline skin incision of at least one inch (for one level), incision of paravertebral fascia, detachment of muscle, removal of a portion of the ligamentum flavum, usually bone removal, retraction of the root and dural sac, and opening of the disc inside the spinal canal.
Minimally invasive endoscopic methods, performed by passing the scope from the skin surface, should be differentiated from open surgery. These are puncture opening (percutaneous) procedures, (with skin openings just large enough to admit the scope), for internal viewing through scope placement directly at the tissue, to be addressed as compared to working from an external view, (either with or without a microscope), through an open incision.
The evolution of these percutaneous methods to the current state-of-the-art can be traced with an historical overview of the basic approaches: chemonucleolysis , laser , manual, and automated percutaneous lumbar discectomy [21, 24, 25, 27], and arthroscopy . In 1948, Valls, et al. , and in 1956, Craig , described the posterior lateral approach for bone biopsy. Lyman Smith first used Chymopapain to treat a lumbar disc disorder in 1964 . The posterolateral extradural route to the lumbar disc was described by Day in 1969 . Percutaneous nucleotomy was developed by Hijikata in 1975 [12, 13, 14]; Kambin, in 1983 , and thereafter, described arthroscopic techniques and equipment for posterior and posterolateral herniated disc removal, via intradiscal access . Then, in 1985, Onik  developed the nucleotome for automated percutaneous lumbar discectomy. In 1987, Choy reported using laser to treat herniated lumbar discs . Subsequently, in 1993, percutaneous endoscopic discectomy with a medium-size, straight, rigid endoscope, at L4-5 and above, was described by Mayer and Brock , in a prospective, randomized series of cases, using manual and automated tools; they reported 95% of endoscopic patients returning to their previous occupations, compared to 72% in their open microdiscectomy group.
More recently, Kambin and others have described larger scope "foraminal access" approaches , but since straight scopes will not go around corners, and large scopes will not pass into small openings, these efforts have been limited to working inside the foramen, or perhaps reaching tools though the foramen, without the advantage of having the entire scope go through in such a way that the scope itself is directly on the actual herniation.
The small, guided endoscopic, completely transforaminal technique (the subject of this paper) was described in detail at the AANS meeting in April, 1996 , and was commended by Dr. Dunsker, an official of the AANS, as "the surgery of the future." (pers. comm.)