3.2 Perioperative complications and recurrence
In the interlaminar group, an intraoperative epineurium injury occurred (3.3%), without cerebrospinal fluid fistula. No limb paralysis or postoperative infections were observed after surgery. One case suffered recurrence 10 weeks after surgery, resulting in a total recurrence rate of 3.3% during the 18-month follow-up. 29 cases (96.7%) return to work three months after surgery. The recurrence case was treated by minimally-invasive transforaminal lumbar interbody fusion.
In the transforaminal group, an intraoperative epineurium injury occurred (3.3%), without cerebrospinal fluid fistula. No limb paralysis or postoperative infections were observed after surgery. No visceral organ or vascular injury occurred. 30 cases (100%) return to work three months after surgery. In addition, no recurrence occurred during the 18-month follow-up (0%).
PELD via the interlaminar or transforaminal approach achieves minimal traumatization, rapid rehabilitation, less intraspinal adhesions, and facilitation of revision operations.[17–20] Moreover, traditional PELD, using techniques such as YESS and TESSYS, is usually performed under local anesthesia, which may cause severe pain, while full-endoscopic visualization technique can be used to perform discectomy under general anesthesia. Although there is no communication with the patients during the procedures, discectomy performed by using full-endoscopic visualization technique under general anesthesia ensures the safety of the surgery via improved visualization of the procedures.[17–20]
Full-endoscopic discectomy via the interlaminar approach can be easily used to perform by spine surgeons with experience in microsurgical discectomy and microendoscopic discectomy, due to the similarity in the approach.[11,18,19] In the present study, full-endoscopic visualization technique was developed and applied via both interlaminar approach and transforaminal approaches. In the interlaminar approach group, full-endoscopic visualized laminectomy and discectomy were performed under visualization to guarantee complete decompression, ensure minimal trauma, and prevent iatrogenic nerve injury.[12,18,19] While in the transforaminal approach group, full-endoscopic visualized foraminoplasty and discectomy were performed under visualization to guarantee complete decompression, ensure minimal traumatization, and prevent iatrogenic nerve injuries.[11,18,19,21] Various endoscopic tools, such as a bone cutter and reamer, can be used in foraminoplasty, and a drill is used in both laminectomy and foraminoplasty.
Previous studies on PELD via the interlaminar and transforaminal approaches have reported the mean operative times ranging 22.0 to 71.3 minutes and 22.0 to 86.0 minutes, respectively.[15,18,22–28] The mean operative times of both groups in the present study were consistent with those in the literature. Furthermore, the mean operative time of the interlaminar group was significantly less than that of the transforaminal group.
During traditional PELD using YESS and TESSYS techniques, preoperative localization of the puncture target, punching procedures, and foraminoplasty are performed under fluoroscopy, resulting in too much radiation exposure. Previous studies have reported the mean fluoroscopy times during interlaminar and transforaminal endoscopic discectomy of 0.6 to 5.5 seconds and 6.5 to 39.4 seconds, respectively.[12,15,26,29,30] In this study, preoperative and intraoperative fluoroscopy was only applied to locate the puncture target and working cannula. full-endoscopic visualization technique provides an opportunity to establish the working cannula under visual control, with less radiation exposure and a shorter fluoroscopy time compared to those in traditional PELD.[15,29,30] Furthermore, the mean fluoroscopy time in the interlaminar group was significantly shorter than that in the transforaminal group.
Due to extensive exposure of the intervertebral disc and nerve root, scarring of the epidural space has been observed postoperatively after conventional surgeries.[31–35] Although only 10% become clinically symptomatic, epidural adhesions have been confirmed on MRI images in many cases. However, full-endoscopic visualization technique via the interlaminar approach preserves most of the ligamentum flavum, and reduces the formation of epidural scar adhesion. Furthermore, no scarring in the access area, and only slight scarring in the spinal canal has been observed in cases of recurrent herniation. Full-endoscopic visualization technique via the transforaminal approach avoids the irritation of the spinal canal and the formation of epidural scar adhesion.
Although minimal traumatization was achieved by full-endoscopic visualization technique, it may be difficult to identify muscle, facet cysts, and ligaments under endoscopic visualization, which increases the risk for iatrogenic injury. Nerve injury, dural tears, and cerebrospinal fluid fistula may occur during surgery. An intraoperative epineurium injury occurred in both groups of the present study. During discectomy performed by using full-endoscopic visualization technique via the transforaminal approach, surgeons must also be vigilant against visceral organ and vascular injuries.
Whether conventional discectomy or full-endoscopic discectomy is applied, recurrence is another important issue. The recurrence rate after PELD has been reported to be 0% to 7.4%.[9,12,14,18,20,25,27,37–43] In the present study, the recurrence rates in the interlaminar and transforaminal groups were 3.3% and 0% respectively, during the 18-month follow-up. Although the recurrence rates in the present study are low, more recurrences may occur in a longer follow-up period. Complete removal of the herniated mass, including the basal and extruded parts, is recommended to reduce the risk of recurrence.
Although cases of recurrent disc herniation were excluded from the present study, full-endoscopic visualization technique via both interlaminar and transforaminal approaches is possible for revision surgeries. Furthermore, full-endoscopic visualization technique via the transforaminal approach can be used to perform discectomy with unscarred virgin tissue to avoid the risk of iatrogenic neural injury and dural tears after surgeries via the interlaminar approach.[12,14,17] Full-endoscopic visualization technique via the interlaminar approach can also be used to perform discectomy with unscarred virgin tissue in cases treated by surgeries via the transforaminal approach.
However, full-endoscopic visualization technique also has some disadvantages, such as a steep learning curve.[36,42] Because the approach is the same as that in conventional discectomy, surgeons are more familiar with full-endoscopic discectomy via the interlaminar approach. As a result, young surgeons may master the full-endoscopic visualization technique via the interlaminar approach more easily than those in the transforaminal approach. Furthermore, in cases of L5-S1 disc herniation, the high iliac crest and narrow foramen determine the difficulty of full-endoscopic visualization technique via the transforaminal approach. In the present study, steep learning curves were observed in both groups, with a steeper learning curve in the transforaminal group compared to that in the interlaminar group. Because of steep learning curves, full-endoscopic visualization technique should be used to perform discectomy by surgeons with experience in microsurgical discectomy and microendoscopic discectomy to reduce the operative time and perioperative complications, and ensure the sufficient decompression of the nerve root.
The present study was also of some limitations, as it is a retrospective, non-randomized controlled cohort study with a small sample size and short follow-up period. It may be difficult to compare the true disc herniation recurrence rate after discectomy in such a short follow-up period. The senior author's personal experience in full-endoscopic visualization technique via both approaches may also bias the results. Further prospective, randomized, controlled studies, as well as more comparative studies, with larger sample sizes and longer follow-up periods, should be conducted to assess the clinical outcomes.
It is efficient and safe to perform discectomy by using full-endoscopic visualization technique via both interlaminar and transforaminal approaches under general anesthesia in patients with L5-S1 disc herniation. Full-endoscopic visualization technique via the interlaminar approach requires a shorter operative time and suffers less radiation exposure than the transforaminal approach.
Conceptualization: Wenbin Hua, Cao Yang.
Data curation: Wenbin Hua, Yukun Zhang, Xinghuo Wu, Yong Gao, Shuai Li, Kun Wang, Xianlin Zeng, Cao Yang.
Formal analysis: Wenbin Hua, Cao Yang.
Funding acquisition: Cao Yang.
Investigation: Wenbin Hua, Cao Yang.
Methodology: Wenbin Hua, Yukun Zhang, Xinghuo Wu, Yong Gao, Cao Yang.
Software: Wenbin Hua.
Supervision: Shuhua Yang, Cao Yang.
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Keywords:Copyright © 2018 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.
discectomy; foraminoplasty; full-endoscopic visualization technique; general anesthesia; interlaminar approach; laminectomy; transforaminal approach