308 Apollo Medicine 2012 December; Vol. 9, No. 4 JaiswalDisruption of the midline supraspinous and interspinous discectomy has an advantage in morbidly obese patientsligament complex in conventional open approaches can where surgical exposure through tubular retractor is betterlead to loss of tension band and thus can result in late post- attained than with conventional retractors used in microoperative instability. MISS avoids the loss of integrity of discectomy.6this midline supraspinous/interspinous complex which in Percutaneous transforaminal endoscopic discectomyaddition to providing structural stability to spine, also acts under local anesthesia is another way of doing MISS foras a tie beam for effective functioning of paraspinal discectomy. Yeung and Hoogland are credited for themuscles.2 Moreover, less muscle disruption in MISS also development of the Yeung Endoscopic Spine Systemleads to decreased blood loss and lesser surgical stress (YESS) in 199711 and the Thomas Hoogland Endoscopicresponse. Spine System (THESSYS) in 1994, respectively.12 The purported advantages are avoidance of general anesthesia, smaller skin incision, conduction as a day care surgeryMINIMALLY INVASIVE LUMBAR and intraoperative active feedback of patient about allevia-DISCECTOMIES tion of radicular symptoms. However, it is not without limi- tations, being applicable for speciﬁc types of discLumbar discectomy has undergone a radical change in herniations and necessitates even steeper learning curves.approach since its ﬁrst description by Mixter and Barr using Superiority of percutaneous techniques over conventionallaminectomy in 1934. Progressively, it was noted that the microdiscectomy still remains unclear as similar outcomesgoal of discectomy and decompression is achievable with has been demonstrated with both methods.lesser invasive approaches. Introduction of use of microscopefor discectomy by Yasargil and Caspar revolutionized thisprocedure and still microdiscectomy is considered as MINIMALLY INVASIVE TRANSFORAMINALa “gold standard”. MISS was described by Foley and Smith LUMBAR INTERBODY FUSIONin 1997 for discectomy using tubular retractors. This relieson dilating the way through muscle ﬁbers rather than stripping Lumbar fusion is commonly done for spinal instability orit from lamina and spinous process. Endoscope or microscope deformity resulting from spondylolisthesis or scoliosis ascan be used as an adjunct for visualization. Many spine well as low back pain from degenerative disc disease refrac-surgeons prefer using microscope owing to 3-Dimensional tory to conservative treatment. Interbody fusion is the mostvisualization and also, as most of them are already acquainted preferred approach for lumbar fusion as it facilitates largerwith use of microscope, while with endoscope, it has limita- surface of fusion bed, opening up of neural foramen throughtion of 2-Dimensional vision and one needs an additional skill “jack up effect” and additional anterior stability when a cageto master due to unfamiliarity. However superiority of MISS is placed. Currently, transforaminal lumbar interbody fusionover microdiscectomy is debated by some as, in microdiscec- (TLIF) is most commonly performed for lumbar arthrodesis,tomy, already there is a minimal surgical exposure and long as TLIF provides exposure of the disc space while requiringterm results of both the approaches have been found to be less dural and nerve root retraction. However in traditionalsimilar.6 Adequate decompression, regardless of the operative open approach TLIF requires extensive surgical exposure.approach used, may be the primary determinant of radicular The iatrogenic injury of muscle and soft tissue is an impor-pain relief. Adversely, it has been noted that there is a higher tant cause of postoperative low back pain which might evenof incidental durotomy in minimally invasive discectomy8 counteract the effects of surgery and sometimes labeled aswith possible explanation being limited visualization, poor “fusion disease.” MISS transforaminal lumbar interbodydepth perception and steep learning curve. Some argue that fusion using nonexpendable or expandable tubular retractormicrodiscectomy can itself be considered as a minimally inva- and bilateral percutaneous screw placement reduces suchsive procedure for discectomy and controversy persists collateral soft tissue damage and has shown to producewhether to stick to age old microdiscectomy or to adopt favorable outcomes in respect to postoperative back pain,tubular discectomy where again, even an experienced spine total blood loss, need for transfusion, length of hospitalsurgeon needs to tide over a steep learning curve. However, stay, time to ambulation and functional recovery.4,5 IliacMISS seems to be more beneﬁcial for spinal procedures crest autograft remains the gold standard, with the osteo-with extensive surgical exposure and soft tissue disruption genic, osteoinductive, and osteoconductive componentslike spinal instrumentation and fusion.4,5,9,10 It can be argued required to achieve fusion, but it comes with associatedthat discectomy is the most common surgery in spine, hence donor site morbidity. Majority of spine surgeons use locallyone should master MISS for discectomy before graduating harvested bone from bony decompression as a graft to avoidto more extensive procedures with MISS. Minimally invasive donor site morbidity. However in MISS transforaminal
Minimally invasive spine surgeries (MISS) Theme Symposium 309interbody fusion when the amount of local graft is inade- MISS has a potential to reduce the approach-relatedquate or even otherwise allograft or bioactive agent like morbidity associated with conventional techniques whichrecombinant human bone morphogenetic protein (rhBMP- is even more crucial in setting of pre-existing injury.2) can be added to facilitate fusion. However MISS has limited indications in thoracolumbar injuries. Pure osseous injuries like bony chance fractures are ideally suited for MISS ﬁxations where one can doMINIMALLY INVASIVE DECOMPRESSIONS IN away without bone grafting and decompression.9 FixationLUMBAR CANAL STENOSIS in such a pure osseous injury has further advantage of possibility of implant removal with restoration of spinalLumbar canal stenosis (LCS) is a common degenerative mobility.9 Spinal fractures needing decompression may beprocess among the elderly leads to progressive neurogenic ﬁxed with percutaneous instrumentation and decompressionclaudication and often needs surgical decompression to can be achieved with expandable tubular retractors or ante-alleviate the associated symptoms and disability. Indeed, rior laproscope/thoracoscopic decompressions.10 HoweverLCS is the most common indication for surgery of the spine one has to conversant with all the procedures and carefullyin patients over the age of 65 years. Conventionally lumbar select fractures types amenable for such MISS interven-laminectomy was indicated surgical procedure for LCS. tions. Speciﬁc clinical indications for MISS interventionsHowever with advances in noninvasive imaging especially in spinal fractures are still evolving.MRI, it was noted that most of these pathologic compres- Percutaneous vertebroplasty and kyphoplasty are mini-sive changes typically occur at the level of the interlaminar mally invasive procedures when performed in symptomaticwindow, hence it seems more prudent to do focal decom- osteoporotic vertebral fractures provides dramatic painpression at level of compression rather than wide laminec- relief to patients who are not responding to conservativetomy. The ultimate goal, regardless of the technique used, is care.13 Vertebroplasty entails the percutaneous injectionto perform an effective decompression of the affected thecal of bone cement into the fractured vertebra, while kypho-sac and nerve root. Current MISS techniques for decom- plasty addresses pain and kyphotic deformity by the percu-pression avoids collateral damage and have successfully taneous expansion of an inﬂatable bone tamp to effectshown to shorten hospital recovery times, reduce intraoper- fracture reduction before cement deposition in a fracturedative complications, and minimize soft tissue trauma with vertebra.resultant decrease in surgical stress response which isa crucial factor in consideration in elderly patients.1e3There has been constant endeavor to adopt a minimally SUMMARYdestructive method to attain aimed surgical neural decom-pression in lumbar canal stenosis. Various methods of Although the authoritative deﬁnition of minimally invasiveless invasive approaches namely spinous process splitting spine surgery remains elusive, the one proposed inapproach, bilateral laminotomies, bilateral decompression summary statement published by McAfee et al14 looksvia unilateral laminotomy etc has been described. MISS most apt. “An MISS is one that by virtue of the extentfor lumbar canal stenosis using tubular retractors aided by and means of surgical technique results in less collateralendoscope or microscope has been employed successfully tissue damage, resulting in measurable decrease into treat LCS.1e3 However, limitation of MISS in LCS morbidity and more rapid functional recovery than tradi-decompression is that it may fail to provide an adequate tional exposures, without differentiation in the intendeddecompression in patients with bony foraminal stenosis. surgical goal.” Growing experience with MISS techniquesIn patients with lumbar stenosis in the setting of spondylo- by operating surgeons and development of newer instru-listhesis, scoliosis, or severe degenerative disc disease, the mentation by manufactures are now enabling an increas-inherent destabilizing nature of posterior decompression, ingly large portion of spine surgical procedures to beeven using MISS, may warrant a fusion operation in addi- performed via minimally invasive techniques.tion to decompression.3 Extensive tissue trauma in traditional surgical exposures cause exaggerated surgical stress response and leads to variety of complications like deep venous thrombosis,MINIMALLY INVASIVE FIXATIONS IN THOR- pulmonary embolism, pulmonary atelectasis, pneumonia,ACOLUMBAR TRAUMA urinary tract infections, ileus, narcotic dependency etc. Indeed, the greater the trauma, the greater the response.Conventional spine exposures add to pre-existing paraspi- MISS plays an important role in reduction of this surgicalnal soft tissue injury secondary to trauma in spinal injuries. stress response and associated complications.7
310 Apollo Medicine 2012 December; Vol. 9, No. 4 Jaiswal Short term beneﬁt like lower intraoperative blood loss, MISS is an exciting development in ﬁeld of spine surgeryfewer infections, less intensive care utilization, less postoper- and to some extent has stood its promise and scientiﬁcallyative analgesia, and shorter hospitalization with MISS vis ratiﬁed. However there is a need of high quality multicentrea vis traditional open surgeries are more as compared to long randomized control studies with large study population toterm beneﬁts. MISS techniques may reduce postoperative clearly elucidate the advantages and disadvantages ofwound infections as much as 10-fold compared with other MISS before it is accepted as a “Gold standard” in spinallarge series of open spinal surgery published in the literature.15 surgeries. Moreover clinicians and researchers need to The steep learning curve of MISS has been one of the constantly endeavor to ﬁnd out ways to simplify the proce-greatest barriers to the widespread adoption of minimally dure, reduce the ﬁnancial implications, reduce the steepinvasive spine surgery. The surgeon practicing this needs learning curve, improve clinical accuracy, reduce peropera-a specialized training and experience. He should be expert tive radiation and broaden the clinical applications of MISS.in doing open surgeries too, as at times he may need toconvert to open procedure, if it is not feasible to carry on CONFLICTS OF INTERESTwith MISS. MISS has a disadvantage of being an instru-mentation dependent procedure. MISS techniques require The author has none to declare.an extensive knowledge of the focal structural/radiologicalanatomy and safe surgical corridors of spinal region ofinterest.16 Additionally, one should be aware of possible REFERENCESanatomical variations and analyze them carefully in preop-erative imaging to avoid operative complications. MISS 1. Asgarzadie F, Khoo LT. Minimally invasive operativerequires signiﬁcant practice and didactic training to acquire management for lumbar spinal stenosis: overview of earlythe skills necessary to perform it safely. and long-term outcomes. Orthop Clin North Am. 2007 MISS entails higher cost of treatment especially in Jul;38(3):387e399. abstract vievii. Review.instrumented cases where the cost of dedicated implants 2. Guiot BH, Khoo LT, Fessler RG. A minimally invasive tech-and instruments is more than once used in traditional nique for decompression of the lumbar spine. Spine (Phila Pasurgeries. However this increase in cost can be offset by 1976). 2002 Feb 15;27(4):432e438.advantages of MISS like lesser hospital stay, lesser compli- 3. Armin SS, Holly LT, Khoo LT. Minimally invasive decom-cations, lesser blood loss and earlier return to functional pression for lumbar stenosis and disc herniation. Neurosurgstatus which allows lesser postoperative expenditure and Focus. 2008;25(2):E11. Review.earlier resumption of productivity of patient.17 4. Shunwu F, Xing Z, Fengdong Z, Xiangqian F. Minimally High radiation exposure to patient and operative team in invasive transforaminal lumbar interbody fusion for the treat-MISS is a cause of concern being 10e20 times greater ment of degenerative lumbar diseases. Spine (Phila Pa 1976).compared to traditional open methods.18 Instrumentation 2010 Aug 1;35(17):1615e1620.in MISS is blindfolded and entails frequent use of ﬂuoros- 5. Peng CW, Yue WM, Poh SY, Yeo W, Tan SB. Clinical andcopy at multiple stages. The steep learning course in MISS radiological outcomes of minimally invasive versus openfurther makes the operating surgeon to use ﬂuoroscope transforaminal lumbar interbody fusion. Spine (Phila Pafrequently to assure proper placement of implants.16 In 1976). 2009 Jun 1;34(13):1385e1389.traditional open procedures, many experienced spine 6. Dasenbrock HH, Juraschek SP, Schultz LR, et al. The efﬁcacysurgeons place pedicle screws with freehand technique of minimally invasive discectomy compared with open discec-based on anatomical landmarks and hardly use intraopera- tomy: a meta-analysis of prospective randomized controlledtive imaging to guide the open placement of pedicle screws, trials. J Neurosurg Spine. 2012 May;16(5):452e462.so a requirement for numerous intraoperative radiographs in 7. Kim CW. Scientiﬁc basis of minimally invasive spine surgery:MISS can be a considerable deterrent to the adoption of prevention of multiﬁdus muscle injury during posterior lumbarminimally invasive techniques. Although, it has been surgery. Spine (Phila Pa 1976). 2010 Dec 15;35(26 suppl):shown that with growing experience the amount of radia- S281eS286. Review.tion tends to decrease but it still remains higher than tradi- 8. Teli M, Lovi A, Brayda-Bruno M, et al. Higher risk of duraltional open approaches. Introduction of computer tears and recurrent herniation with lumbar micro-endoscopicnavigation and continuous electromyography (EMG) moni- discectomy. Eur Spine J. 2010 Mar;19(3):443e450. Epubtoring as an adjunct in MISS19 has potential to reduce the 2010 Feb 3.amount of radiation, but again the navigation systems are 9. Schizas C, Kosmopoulos V. Percutaneous surgical treatmentnot widely available owing to high establishment cost and of chance fractures using cannulated pedicle screws. Reportneed of additional dedicated technical expertise. of two cases. J Neurosurg Spine. 2007 Jul;7(1):71e74.
Minimally invasive spine surgeries (MISS) Theme Symposium 31110. Rampersaud YR, Annand N, Dekutoski MB. Use of minimally 15. O’Toole JE, Eichholz KM, Fessler RG. Surgical site infection invasive surgical techniques in the management of thoracolum- rates after minimally invasive spinal surgery. J Neurosurg bar trauma: current concepts. Spine (Phila Pa 1976). 2006 May Spine. 2009 Oct;11(4):471e476. 15;31(11 suppl):S96eS102. discussion S104. Review. 16. Lee JC, Jang HD, Shin BJ. Learning curve and clinical11. Yeung AT, Tsou PM. Posterolateral endoscopic excision for outcomes of minimally invasive transforaminal lumbar inter- lumbar disc herniation: surgical technique, outcome, and body fusion: our experience in 86 consecutive cases. Spine complications in 307 consecutive cases. Spine (Phila Pa (Phila Pa 1976). 2012 Aug 15;37(18):1548e1557. 1976). 2002 Apr 1;27(7):722e731. 17. Allen RT, Garﬁn SR. The economics of minimally invasive12. Hoogland T, Schubert M, Miklitz B, Ramirez A. Transforami- spine surgery: the value perspective. Spine (Phila Pa 1976). nal posterolateral endoscopic discectomy with or without the 2010 Dec 15;35(26 suppl):S375eS382. Review. combination of a low-dose chymopapain: a prospective 18. Mariscalco MW, Yamashita T, Steinmetz MP, randomized study in 280 consecutive cases. Spine (Phila Pa Krishnaney AA, Lieberman IH, Mroz TE. Radiation expo- 1976). 2006 Nov 15;31(24):E890eE897. sure to the surgeon during open lumbar microdiscectomy13. Phillips FM. Minimally invasive treatments of osteoporotic and minimally invasive microdiscectomy: a prospective, vertebral compression fractures. Spine (Phila Pa 1976). controlled trial. Spine (Phila Pa 1976). 2011 Feb 2003 Aug 1;28(15 suppl):S45eS53. Review. 1;36(3):255e260.14. McAfee PC, Phillips FM, Andersson G, et al. Minimally inva- 19. Wood MJ, Mannion RJ. Improving accuracy and reducing sive spine surgery. Spine (Phila Pa 1976). 2010 Dec 15;35(26 radiation exposure in minimally invasive lumbar interbody suppl):S271eS273. fusion. J Neurosurg Spine. 2010 May;12(5):533e539.