Spinal and epidural endoscopy: a historical review.

In current-day medicine, endoscopy plays an important role in the diagnosis and treatment of many different conditions. This improving technology has led to new areas of endoscopic visualization, particularly of the epidural space, spinal cord and contiguous structures. A review of the medical literature indicates that clinicians have been working with various types of endoscopes for over sixty years, with varying degrees of success. Only recently has fiberoptic technology been integrated with computer-enhanced imaging to provide a new medium for viewing the central nervous system. The initial results are promising and will likely pave the way for newer, less invasive means of diagnosis and treatment of central nervous system pathology. The direct visualization of the spinal canal and its contents was born in 1931 from the pioneering work of Michael Burman, an orthopedic surgeon from the New York Hospital for Joint Diseases [1]. With each decade since then, myeloscopists and epiduroscopists have attempted to develop a means of fiberoptic visualization that would be easy and safe to apply in medical practice. Unfortunately, until the recent advent of both flexible fiberoptic light sources and optics [2], this could not be achieved. In 1931, Burman removed eleven vertebral columns from cadavera and examined them using then-currently available arthroscopic equipment with the hope of developing a minimally invasive technique for the assessment of spinal pathology. As might be expected, the diameter of the trocar in which the lamp was mounted was greater than the average width of the spinal canal itself (approximately 3/8 inch or 9.5 mm). Thus, the viewing lens often was not completely within the spinal canal. In some locations, the spinal canal was wide enough to allow insertion of the scope, permitting visualization of the spinal canal contents such as the dura mater, blood vessels and the cauda equina. However, the field of view allowed by the scope was limited to one inch (2.54 cm). Burman thus concluded that myeloscopy was limited by the available technology, but that with higher quality instrumentation, a better postmortem examination of the cauda equina could be performed in situ. He felt that the ability to visualize the contents of the spinal canal might be especially important in establishing a diagnosis of tumor or inflammation, although he did not anticipate the possibility that an improved device might also allow advances in therapy. In 1936, Elias Stern from Columbia University's Department ofAnatomy was among the first to describe a spinascope [3]. A working model of this instrument (Figures 1 and 2) was manufactured by American Cystoscope Makers, Inc., and it was specifically designed for the in vivo examination of the spinal canal contents during spinal anesthesia. The instrument was never used clinically, but Stern did envision its use for the direct observation of the posterior roots for rhizotomies in patients with intractable pain and sectioning of these roots for treatment of spastic conditions. With technologic improvements,