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Microendoscopic discectomy for treatment of lumbar disc herniation

A lumbar microendoscopic discectomy(MED)is a minimally invasive surgical technique performed through a tubular device which is designed for the pain relieve caused by herniated discs pressing the nerve roots. In 1997， a new minimally invasive surgical approach for the management of symptomatic lumbar disc herniation， MED was introduced. This technique uses a tubular retractor system and a microendoscope for visualization rather than the operating microscope. However， recent literature suggests that MED is an effective microendoscopic system which has a fine long-term outcome in treating lumbar disc herniation. This article describes the operative techniques and outcomes reported in the literature for MED.

discectomy; mircoendoscope; lumbar disc herniation; review article

1 Introduction

Sciatica describes the symptoms of leg pain and occasionally disturbance in the dermatome of the affected nerve root. It is caused by nerve root compression or irritation and over 90% of cases are due to lumbar disc herniation (LDH)[1]. The symptoms of sciatica can be disabling and around 30% of patients will still report symptoms beyond one year[2]. Typically， symptoms are experienced only on one side of the body.

The number of patients with LDH is increasing simultaneously among all population including young age. Western people(about 70%-85%) go through at least one episode of low back pain with or without leg pain during their lives and are the most common reason for hospital visits[3]. Disc degeneration occurs both with degenerative disc disease and aging[4]. Professional athletes， especially those playing contact sports， are prone to disc herniation[5]. Conservative treatment includes physiotherapy， hydro-therapy， and analgesia are routinely used. If such pain does not respond to conservative therapy， it may be treated surgically. Surgical option includes chemonucleolysis， open discectomy (OD)， microdiscectomy (MD)， and microendoscopic discectomy (MED).

In 1934， William Mixter and Joseph Barr are well known for the detailed description of a lumbar discectomy procedure in the treatment of lumbar and sciatic pain due to disc herniation. In 1977 and 1978， Yasargil[6]， Caspar[7]and Williams[8]all described microsurgical techniques for discectomy using the operating microscope. For the patients with symptomatic lumber disc herniation causing radiculopathy who require surgery， lumbar microdiscectomy is considered the treatment of choice which was not improved with conservative measures. In 1983， Forst et al.[9]first reported the insertion of modified arthroscope into the intervertebral disc space for direct visualization of the disc space.

Canby and Silber et al.[10-11]designed MED system in 1997 which allowed spine surgeons to decompress a symptomatic lumbar nerve root constantly using an endoscopic， minimally invasive surgical technique. The second generation MED system was developed in 1999， called METRx (Medtronic Sofamor Danek， Inc.， Memphis， TN). It consists of a guide wire， a series of sequential dilators， a tubular retractor system， a rigid endoscope with other endoscopic assembly and a standard video monitor system. Recently， with the advancement in surgical techniques and instruments， spinal microendoscopy has also come to be used for various conditions such as， lumbar spinal stenosis and cervical myelopathy[12].

2 MED Surgical Technique

Surgery is carried out under spinal or general anesthesia with patients in prone position， with the abdomen free in order to reduce intraoperative venous bleeding. A longitudinal skin incision of 16-20 mm is made approximately 6 cm lateral to the midline. The METRx MED system is used for surgery. After dissection of the fascia， a guide wire is inserted and directed toward inferior aspect of the superior lamina and facet joint under lateral C-arm fluoroscopic guidance and a dilator with a diameter of 5.3 mm is inserted toward to the base of the transverse process of the lower vertebra with the dilator tilted inward at 30°-45°.

The first step is to fully expose the cranial half of the base of the transverse process and the lateral edge of the superior articular process of the lower vertebra using electro-cautery knife. After this， the caudal part of the upper vertebral lamina and the ligamentum flavum are resected partially， and then the discectomy is performed.

Finally， the intervertebral space is irrigated with saline solution with higher pressure in order to swill out the remaining fragments. The wound is also irrigated to clean away cotton fiber， bone chips， blood clots， and so on. The patients are allowed to walk in 1-2 days after surgery.

3 Literature review

Open discectomy was once regarded as the “gold standard” treatment of herniation. However， it destroys the rear structure of spine， causing segmental instability and long-term distress. In 2002 by Asch et al.[13]， the most statistically rigorous paper detailing outcomes after lumbar microdiscectomy was published. In this prospective study of 212 patients， eighty percent experienced relief of leg pain with a mean follow-up of 2 years. This result is similar to many others published in the literature[14-15]. Muramatsu et al.[16]reported on their series of 25 patients who underwent MED and 15 patients for whom Love’s method was used to treat lumbar disc disease. MED had an effect on the nerve roots and cauda equina that was comparable with that of Love’s method. In the Schick et al. intraoperative EMG study[17]， 15 patients with LDH were treated with an endoscopic medial technique， and 15 patients with the open microscopic surgical technique， results showed that the endoscopic technique was better than that of open surgical technique and produced less irritation of the nerve root.

In the study of Wu et al.[18]， surgical technique and outcome in 873 consecutive cases treated via MED reported that MED is an effective microendoscopic system with fine-long term outcome in treating LDH. Hence， it is also stated in this study that strict adherence to well-defined pre-operative patients selection criteria could ensure optimal good post-operative results. Huang et al.[19]concluded in his study that MED is favorable as it appeared to reduce ‘surgical stresses’ to the patient compared with OD. Moreover， MED patients had achieved satisfactory clinical outcomes than the OD patients. In another study of Perez-Cruet et al.[11]， these surgeons reported 94% of good to excellent results according to the modified MacNab criteria. In this study， they also stated that MED for LDH can be performed safely and effectively， resulting in a shortened hospital stay and faster return to work.

MED is the standard method， and highly reliable for treatment of LDH. Most patients in the general population are able to return to daily activities and are satisfied with their results. Watkins et al.[20]reported that 88.3 % of professional and Olympic athletes were able to return to competitive sports in 5.2 months after the surgery. Also， Weber et al.[21]reported that 82.9 % of athletes were able to return to sporting activity in 5.8 months after the surgery. In another study by Yoshimoto et al.[22]stated that this study recommends MED as a well-balanced technique for athletes， offering a high probability and early return to sporting activities， which is the optimal aim for the treatment of LDH.

In the recent study， Yoshimoto et al.[23]proved that MED technique is the standard approach for the treatment of lumbar foraminal stenosis. In the study， the efficacy of MED in reducing iatrogenic muscle injury performed by Shin et al.[24]， reported that MED technique is less invasive than MD and caused less muscle damage and less back pain. Percutaneous endoscopic lumbar discectomy (PELD) an alternative surgical method in the treatment of far lateral lumbar disk herniation， several authors reported the feasibility of PELD[25]. Although PELD is the most minimally invasive method， it takes a long time to master the technique. In the recent study， MED for far lateral lumbar disk herniation: less surgical invasiveness and minimum two year follow-up results， in 2014 by Yoshimoto et al.[26]， stated that MED is a standard procedure which offers both reduced invasiveness and reliable in the treatment of far lateral LDH.

4 Conclusion

Numerous surgical interventions are used by surgeons in present days for the treatment of LDH. Various international studies have reported the superiority of MED approach in the treatment of LDH. Though some spine surgeons have introduced more minimally invasive techniques in recent years like， percutaneous endoscopic lumbar discectomy (PELD)， trasforaminal endoscopic discectomy (TED) and so on， it takes a long time to master these techniques. The MED system offers the benefits of a smaller incision than other surgical techniques and limited to tissue trauma with less irritation for nerve root. Hence， MED is a safest and successful endoscopic system which has a fine long-term clinical outcome in the treatment of LDH. In conclusion， further large prospective， randomized study with long term follow-up needs to be done to have the better outcomes.

[1] VALAT J P,GENEVAY S,MARTY M,et al.Sciatica[J].Best Pract Res Clin Rheumatol,2010，24(2):241-252.

[2] WEBER H,HOLME I,AMLIE E.The natural course of acute sciatica with nerve root symptoms in a double-blind placebo-controlled trial evaluating the effect of piroxicam[J].Spine,1993，18(11):1433-1438.

[3] ANDERSSON G B.Epidemiological features of chronic low-back pain[J].Lancet,1999，354(9178):581-585.

[4] Del GRANDE F,MAUS T P,CARRINO J A.Imaging the intervertebral disk: age-related changes,herniations,and radicular pain[J].Radiol Clin North Am,2012，50(4):629-649.

[5] EARHART J S,ROBERTS D,ROC G,et al.Effects of lumbar disk herniation on the careers of professional baseball players[J].Orthopedics,2012，35(1):43-49.

[6] YASARGIL M G.Microsurgical operation for herniated lumbar disc[M]//WULLENWEBER R,BROCK M,HAMER J,et al.Advances in neurosurgery.Berlin:Springer-Verlag,1977:81.

[7] CASPAR W.A new surgical procedure for lumbar disc herniation causing less tissue damage through a microsurgical approach[M]//WULLENWEBER R,BROCK M,HAMER J.Advances in Neurosurgery.Berlin: Springer-Verlag,1977:74-77.

[8] WILLIAMS R W.Microlumbar discectomy:a conservative surgical approach to the virgin herniated lumbar disc[J].Spine,1978，3(2):175-182.

[9] FORST R,HAUSMANN B.Nucleoscopy:a new examination technique[J].Arch Orthop Trauma Surg，1983，101(3):219-221.

[10] FOLEY K T,SMITH M M,RAMPERSAUD Y R.Microendoscopic approach to far-lateral lumbar disc herniation[J].Neurosurg Focus,1999，7(5):e5.

[11] PEREZ-CRUET M J,FOLEY K T,ISAACS R E,et al.Microendoscopic lumbar discectomy:technical note[J].Neurosurgery,2002，51(5 Suppl):S129-S136.

[12] KHOO L T,FESSLER R G.Microendoscopic decompressive laminotomy for the treatment of lumbar stenosis[J].Neurosurgery,2002，51(5 Suppl):S146-S154.

[13] ASCH H L,LEWIS P J,MORELAND D B,et al.Prospective multiple outcomes study of outpatient lumbar microdiscectomy:should 75 to 80% success rates be the norm？[J].J Neurosurg,2002，96(1 Suppl):34-44.

[14] ABRAMOVITZ J N,NEFF S R.Lumbar disc surgery:results of the prospective lumbar discectomy study of the joint section on disorders of the spine and peripheral nerves of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons[J].Neurosurgery,1991，29(2):301-307,7-8.

[15] QUIGLEY M R,BOST J,MAROON J C,et al.Outcome after microdiscectomy:results of a prospective single institutional study[J].Surg Neurol,1998，49(3):263-267,7-8.

[16] MURAMATSU K,HACHIYA Y,MORITA C.Postoperative magnetic resonance imaging of lumbar disc herniation:comparison of microendoscopic discectomy and Love′s method[J].Spine,2001，26(14):1599-1605.

[17] SCHICK U,DOHNERT J,RICHTER A,et al.Microendoscopic lumbar discectomy versus open surgery:an intraoperative EMG study[J].Eur Spine J,2002，11(1):20-26.

[18] WU X,ZHUANG S,MAO Z,et al.Microendoscopic discectomy for lumbar disc herniation:surgical technique and outcome in 873 consecutive cases[J].Spine,2006，31(23):2689-2694.

[19] HUANG T J,HSU R W,LI Y Y,et al.Less systemic cytokine response in patients following microendoscopic versus open lumbar discectomy[J].J Orthopaedic,2005，23(2):406-411.

[20] WATKINS R G T,WILLIAMS L A,WATKINS R G 3rd.Microscopic lumbar discectomy results for 60 cases in professional and Olympic athletes[J].Spine,2003，3(2):100-105.

[21] WEBER J,SCH?NFELD C,SPRING A.Sports after surgical treatment of a herniated lumbar disc:a prospective observa-

tional study[J].Z Orthop Unfall,2009，147(5):588-592.

[22] YOSHIMOTO M,TAKEBAYASHI T,IDA K,et al.Microendoscopic discectomy in athletes[J].Orthopaedics,2013，18(6):902-908.

[23] YOSHIMOTO M,TAKEBAYASHI T,KAWAGUCHI S,et al.Minimally invasive technique for decompression of lumbar foraminal stenosis using a spinal microendoscope:technical note[J].Minim Invasive Neurosurg,2011，54(3):142-146.

[24] SHIN D A,KIM K N,SHIN H C,et al.The efficacy of microendoscopic discectomy in reducing iatrogenic muscle injury[J].Neurosurg Spine,2008，8(1):39-43.

[25] CHOI G,LEE S H,BHANOT A,et al.Percutaneous endoscopic discectomy for extraforaminal lumbar disc herniations:extraforaminal targeted fragmentectomy technique using working channel endoscope[J].Spine,2007，32(2):E93-E99.

[26] YOSHIMOTO M,IWASE T,TAKEBAYASHI T,et al.Microendoscopic discectomy for far lateral lumbar disk herniation:less surgical invasiveness and minimum 2-year follow-up results[J].J Spinal Disord Tech,2014，27(1):E1-E7.

ARJUN Sinkemani1，WU Xiao-tao2

(1.SchoolofMedicine，SoutheastUniversity，Nanjing210009，China; 2.DepartmentofOrthopedics，ZhongdaHospital，SoutheastUniversity，Nanjing210009，China)

WU Xiao-tao E-mail:wuxiaotao@medmail.com.cn

format] ARJUN Sinkemani，WU Xiao-tao.Microendoscopic discectomy for treatment of lumbar disc herniation[J].J Southeast Univ(Med Sci Edi)，2015，34 (3):479-482.

R816.8 [Document code] A [Article ID] 1671-6264(2015)03-0479-04

10.3969/j.issn.1671-6264.2015.03.038

[Received date] 2014-12-25 [Revised date] 2015-01-14

[Biographies] ARJUN Sinkemani(1984-)，M，Nepalese，Nepal,Postgraduate student.E-mail:sinkemani@hotmail.com