The role of endoscopy is expanding in the diagnosis and treatment of many medical conditions, but the use of this technology in spine care is still in its infancy. The technology of spinal canal endoscopy has developed slowly over the past century, initially as a rigid and later as a flexible endoscope. As such, the epiduroscopy technology with flexible optics has been used for clinical application only since the early 1990s.1
In 1931, Michael Burman,2 an orthopedic surgeon at the Hospital for Joint Diseases New York, described the visualization of the spinal canal and its content. For his pioneering study, he used a rigid arthroscopic instrument with incandescent light source to visualize and study cadaver vertebral columns. It is noteworthy to point out that the diameter of the trocar in which the lamp was mounted (~3/8 inch or 9.5 mm) was greater than the average width of the spinal canal itself. Thus, the viewing lens was only in the wide areas of the spinal canal where the scope could be inserted to visualize and evaluate anatomical structures such as the dura mater, blood vessels, and the cauda equina.
Five years later, in 1936, Elias Stern3 from Columbia University developed a spinascope, which was intended to be used in vivo to examine the contents of the spinal canal during spinal anesthesia. His vision was to use his technique to perform posterior rhizotomies for intractable pain and spastic conditions under direct visualization.
In 1937, J. Lawrence Pool,4 an American neurosurgeon, used the myeloscope to improve the preoperative diagnostic assessment of patients with lumbar–sciatic syndrome under anesthesia. His initial challenge was bleeding, which obscured his view; thus, a clear visualization of the lumbosacral nerve roots was not possible. Fortunately, he was able to improve his technique and thus in subsequent evaluation, he was able to visualize and report about cauda equina and blood vessels, and blood flow through epidural vessels in seven volunteer patients without complications. A few years later, Pool published a summary of his experience with 400 patients.5,6 He was able to diagnose or confirm the diagnosis of various types of spine pathologies, including neuritis, herniated nucleus pulposus, hypertrophied ligamentum flavum, primary and metastatic neoplasms, varicose vessels, and arachnoid adhesions. Unfortunately, this technique was not picked up by others and it took almost 30 years to read about this technique again. One of the main drawbacks of this technique was the fact that it was not possible to capture images during the procedures.7
As the era of fiberoptics emerged, Ooi et al8,9,10,11 developed an endoscope for intradural and extradural examinations. Their device, which was inserted via the lumbar interspinous processes, was much leaner compared to the device used by their predecessors.11 Interestingly, for the first time, the device (1.8-mm rigid scope and fiberoptics were used as a light source) enabled them to record black and white photographic images of ligamentum flavum, epidural adipose tissue, the surface of the dural sac, and the cauda equine. Most importantly, they did not report any serious complications from their initial 86 cases.12 As the authors gained more experience and performed increased number of cases, they published an interesting article on myeloscopy and blood flow changes of the cauda equina during Lasègue’stest.13 On the other hand, even though the attempt to explore the epidural space using myeloscopy with rigid optics was unsatisfactory, it was not until the late 1980s when a small caliber flexible optics was developed for clinical application of epiduroscopy.
In 1985, Rune Blomberg14 was the first to observe and describe the content of the epidural space using a small rigid endoscope with fiberoptic light source. He observed that the content of the epidural space varied widely in terms of fat and connective tissue. Furthermore, Blomberg and Olsson15
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