Videoendoscopy for Treating Degenerative Disc Disease with Lumbar Canal Stenosis Techniques Portals and instrumentationA Systematic Review

The main objective of this study was to present a systematic review covering the main indications, results and complications of video endoscopic surgery in the treatment of this associated diseases disc degeneration with lumbar canal stenosis. Studies show that the best form of treatment for this condition is a surgical decompression that has lately been associated with endoscopy video. The main objective of this study was to present a systematic review about the indications, results and complications of endoscopic video surgery in the treatment of lumbar degenerative disc disease with canal stenosis. A systematic review was adopted using the keywords “endoscopy” “ disc disease” and “stenosis” interspersed by the boolean operator “AND”. The databases selected for search were: PubMed, Scielo, LILACS and Cochrane plus manual research in gray literature. Studies published from 2000 in English, Portuguese and Spanish were included, and literature and systematic reviews were excluded. The results indicate that surgical decompression associated with endoscopic video foraminoplasty improves pain scores and reduces patient morbidity and increase the movement of the lower limbs.


Introduction
Lumbar disc degenerative disease with canal stenosis is considered a disease resulting from aging because it affects the intervertebral discs through progressive degeneration and, at the same time, arthrosis of the posterior articular facets occurs, resulting in a narrowing of the spine [1]. According to Brandt et al [1], stenosis "can cause compression of one or more roots of localized, segmented or generalized, through bone, disc or ligament structures". Videoendoscopy for the treatment of isolated lumbar herniated discs is now common place with favorable clinical results comparable to microdiscectomy and a low rate of complication rate. The transforaminal approach is frequently applied to the endoscopic treatment of herniated discs mainly at the L3/L4, and L4/L5 level. The approach is also feasible at L5/S1 but may be technically more demanding because of the configuration of the iliac wing, sacralization of the L5 vertebral body, or because of degenerative vertical collapse of the spine. Placing the working cannula may be harder at this transitional level due to steeper attack angles making injury to the exiting L5 nerve root more likely. Regardless of the level, additional risks for nerve root injury due to increasing surgery time and more aggressive manipulation may arise if the surgeon is attempting to access a highly stenotic neuroforamen during the endoscopic decompression procedure.
The lumbar disc disease with canal stenosis may have a congenital, acquired origin or an association between the two forms. Congenital stenosis is the result of achondroplasty while acquired stenosis is associated with spondylolisthesis. Thus, with aging and degeneration, the intervertebral disc loses its viscoelastic characteristic, with the possibility of lacerations in the fibrous annulus, fragmentation of the pulpal nucleus and, consequently, loss of disc height " [1]. Conventional treatment includes local decompression of the lumbar region with hemilaminectomy or laminectomy, with a view to releasing the vertebral foramina.
The insertion of video endoscopy has brought many benefits for the treatment of lumbar canal stenosis in this aspect, such as greater accuracy and sensitivity at the time of surgical access and manipulation [2], but because it is a relatively new and still littleused treatment method, in addition to of needing specialized training with a specific learning curve more than de simple videoendoscopic discectomies, even today it raises questions about its indication, results and complications. In view of these considerations, the main objective of this study was to present a systematic review covering the main indications, results and complications of video endoscopic surgery in the treatment of this associated diseases disc degeneration with lumbar canal stenosis.

Inclusion Exclusion
Articles, theses, dissertations and monographs available in full Works that are not available in full In the manual search of the references present in the potentially eligible studies, 2 works of interest and possibly of applicability in this research were verified, that is, after searching a list of 457 references. However, these 2 studies were removed after reading the summary because they did not meet the inclusion and exclusion criteria. However, after a complete reading of the 14 potentially eligible articles, 6 were excluded due to lack of qualification in this research.
However, after the selection process, 12 articles were listed for qualitative analysis. The selection process is summarized in the flowchart in Figure 1. Below, the 12 papers selected for the review are presented in Table 1, subdivided into: Author, Year, Type of study, Sample, Results and Considerations [3][4][5][6][7][8][9][10][11][12][13][14].  The foraminoplasty procedure is specially designed to be a less invasive, effective and safe surgery for stenosis of the lumbar lateral recess with / without combined HD.
Knight et al. [11] 2014 112 patients with lumbar stenosis treated with transforaminal endoscopy associated with foraminoplasty, analyzed 10 years after the surgical procedure.
Pain scores significantly decreased, and decompression was successful in more than half of the patients analyzed.
Treatment is effective for decompression of lumbar stenosis.
Kim et al [12] 2011 Case series 5 patients with lumbar canal stenosis operated with video endoscopy through contralateral access and foraminoplasty Pain scores showed a significant reduction and decompression was successful in all cases.
The success of the PELD procedure depends on the proper placement of the work instruments. An inappropriate path for pathology is one of the main causes of the failure of this procedure.

Discussion
Lumbar disc degenerative with canal stenosis as known can occur as part of a generalized disease process and involves several areas of the canal and several levels or, conversely, can be located or segmented [15], all the studies analyzed demonstrate the importance of the surgical approach in cases refractory to conservative and physiotherapy treatment as the only alternative for satisfactory clinical improvement. One of the most common problems after transforaminal endoscopic decompression is dysesthesia due to compression of the dorsal root ganglion by the working cannula and its manipulation during its initial placement and the discectomy procedure and because of this, most authors prefer an interlaminar approach to start decompress of the stenosis by drilling facets and laminae and in sequence open the flavor ligament and proceed the discectomy.
The main signs and symptoms include painful radiculopathy associated with neurological deficits that can significantly affect the movement of lower limbs on the affected side. The introduction of corticosteroids in the subdural space has been described, but the results are inconstant and of short duration, and in the case of its ineffectiveness, the surgical procedure is also adopted [16].
According to the studies presented, lumbar decompression is the main form of treatment for this condition. The technique has been improved over the years and the addition of video endoscopy as an aid to visualize the exact lesion site [10].
The camera can be inserted via uniportal or biportal access.
In the uniportal access, the instruments for manipulation and the camera are inserted in the same place, whereas, in the biportal access, the instruments are placed by one access and the camera by another [17]. Kim et al [6] considered the uniportal access adequate and sufficient for decompression of lumbar stenosis, however they emphasize that this study is considered preliminary and despite having presented a good improvement regarding decompression, they suggest more rigorous and long-term analyzes to verify efficacy and safety. Eum et al. [5] on the other hand, prefer percutaneous biportal endoscopy because they consider it very similar to microscopic spinal surgery, allowing a good visualization of the contralateral sublaminar and medial foraminal areas, they believe that it is a more appropriate approach in cases of severe compression, which was reinforced by Heo et al [9] who considered safe and effective treatment, with great advantages over open treatment.
Finally, Shin et al [14] emphasize that transforaminal endoscopic decompression can be performed on an outpatient basis under local anesthesia and that it can be an effective and low-cost treatment method for the selected group of patients with lumbar canal stenosis.

Conclusion
Video endoscopic surgical decompression improves pain and functional disability scores in lumbar degenerative disc with canal stenosis, is a safe technique, allows proper decompression of the canal and should be incorporated into the technical arsenal of the spine surgeon.