Dong Hwa Heo, MD. PhD Department of Neurosurgery, Endoscopic spine surgery center, Seoul Bumin Hospital, South Korea Cheol Woong Park, MD. PhD. Department of Neurosurgery, Spine center, Daejeon Woori Hospital, South Korea Sang Kyu Son, MD. Department of Neurosurgery, Spine center, Parkweonwook Hospital, South Korea Jin Hwa Eum, MD. PhD Department of Neurosurgery, Spine center, Burjeel Royal Hospital , UAE