Spinal endoscopy: the history, evolution, and applications

History and development: As we continue to better define the true indications of surgical procedures and ultimately refine these procedures to improve their inherent morbidity, the development of spinal endoscopic techniques continue to enhance minimally invasive surgical procedures. Surgeons desire to define anatomy and to visualize pathology long preceded our ability to utilize sophisticated imaging techniques. Visualization tools using rod-lens technology have been employed for use in the intracranial and in the myeloscopic visualization of neuroanatomy. Pool in 1942 described a large series of myeloscopic inspections of intrathecal normal and abnormal anatomy. His classic diagrams display the presence of disc herniations, arachnoiditis, and spinal stenosis from intrathecal inspections performed through a large bore myeloscope ( Figure 1 ). The continued evolution of myeloscopy was thought to be essential for the treatment of arachnoiditis, large herniated disc disease, and intrathecal tumor pathology. Its complications, however, led to its disuse because of the large bore scope requirements and the morbidity required to insert this instrumentation in the appropriate neural cavity.