Lumbar disc herniation is one of the common causes of low back pain with sciatica in young and adult with huge economic burden to family and society [1] [2] [3] . Point prevalence of lumber disc herniation is 37.1%, 1-year prevalence of 76.0%, and lifetime prevalence of 85.5% [4] . About 70% - 80% of population experiences back pain in lifetime. It’s reported that the prevalence of herniated discs are higher among people 35 - 45 years old [5] . Not all herniated disc need operative treatment but when sign and symptoms such as back with or without radicular leg pain progressively increase despite of conservative treatment for more than 6 weeks, neurological deficits as foot drop, cauda equine, etc. are seen then has to undergo for surgery. Currently, there are numerous surgical interventions for lumber disc herniation. They can be broadly classified as posterior open discectomies and percutaneous techniques. Posterior open discectomies include open laminectomy and discectomy, micro discectomy, micro endoscopic discectomy, hemi laminectomy with discectomy, among which micro discectomy remains the standard surgery for lumber disc herniation. Whereas, percutaneous techniques include chemonucleolysis, nucleoplasty, intradiscal electrothermal therapy, percutaneous laser discectomy and percutaneous endoscopic lumbar surgery (PELS) [6] [7] [8] . Except PELS, all of the percutaneous techniques are blind procedure, whereas, PELS is performed under direct endoscopic vision.

Percutaneous endoscopic lumbar surgery is one of the latest emerging techniques in treatment of lumbar disc herniation. Kambin and Gellman in 1973 and Hijikatain 1975 first introduced non-visualized percutaneous central nucleotomy via posterolateral approach [9] [10] . After introduction of direct visualization of intervertebral disc space with modified arthroscopy by Forest and Housman in 1983, this technique has been widely practiced for treatment of lumber disc herniation [7] . In 1992 Kambin P. further defined removal of protruded disc passing through Kambin’s triangle, considered to be a safe site in posterolateral region [11] . Recently, there are 2 techniques widely used for percutaneous endoscopic surgery: 1) transforaminal approach described by Yeung (Yeung Endoscopic spinal surgery, YESS) in 1997 and Hoogland (Transforaminal endoscopic spine surgery system, TESSYS) in 1994 [12] [13] ; 2) Interlaminar approach described by Ruetten in 2008 [14] . The indications for transforaminal endoscopic treatment are the same as classical discectomy procedures. Now due to advancement of instrumentation and skill of surgeon indication has broadened.

If the surgery is indicative then all pre-operation evaluation and preparation are performed; this surgery can be done in two positions; prone or lateral decubitus position. If the patient is placed in prone position then hip and knee are flexed and pillow is placed between lower abdominal and chest so that abdomen is hanged freely. For lateral decubitus position, pillow is placed under the waist, which will open up the foramen and allow the Dura to fall down to the contra-lateral side avoiding damage on introduction of the cannula and the also reduced intra-abdominal pressure and decrease bleeding. Then under guidance of C-arm, entry point is marked 8 - 16 cm from midline of vertebra to lateral side according to the disc interval at an angle of 15 - 25 degrees in horizontal plane [15] [16] . Under all aseptic condition and local anesthesia (1%lidocane), and under anteroposterior (AP) and lateral view, a 25 cm 18 gauge needle is inserted in the level of herniated disc through the posterolateral approach. Intraoperative discogram is then performed with a 2 mL mixture of contrast medium and methylene blue at the ratio of 9:1 and help of c-arm. If the dye is seen in the epidural space nucleus then it indicates the herniated fragment. Then guide wire is inserted and the needle is removed leaving the guide wire in situ. A small skin incision of 8 mm is then given over the guide wire entry point. A 2 mm conical rod is introduced over the guiding wire, and then sequentially the first, second and third sleeves were inserted dilating the soft tissues up to 6.5 mm. Then the reamer is introduced anti clockwise, to avoid damage to the spinal muscles and continuously under the guidance of image intensifier reamed to 1 or 2 mm inside the medial pedicular line. The procedure is repeated with each of the sequentially larger rods, tubes and reamers. Then working cannula is introduced over the third conical rod and its tip should be located on the herniated disc. Then image intensifier is removed and working endoscope set introduced and herniated disc is removed under direct visualization as in Figure 1. After complete decompression, the dural sac and the lumber exiting nerve root is checked for freely movable with the valsalva maneuver. Bleeding of the small vessels is controlled with a flexible bipolar radio frequency probe. Communication with patients is maintained throughout the procedure. Though the technique is considered to be much safer but it involves several technical challenges, such as the critical narrow access through the foraminal triangular window and the limited intradiscal and epidural working space.

In recent time, percutaneous endoscopic lumbar surgery specially transforaminal approach is widely used to treat lumber disc herniation due to its comparable significant outcome as shown in Table 1. This transforaminal approach can be approached by two techniques YESS and TYSSYS. The standard indication for percutaneous transforaminal endoscopic lumber discectomy (PTELD) is limited to soft (non calcified) and contained LDH, which caused discogenic leg pain that