Technique and Outcomes of Transforaminal Endoscopic Lumbar Discectomy for Bilateral Disc Herniation

Article information

J Minim Invasive Spine Surg Tech. 2026;11(Suppl 1):S132-S142

Publication date (electronic) : 2026 January 30

doi : https://doi.org/10.21182/jmisst.2025.02551

Sang-Ha Shin, Pratyush Shahi, Sang-Ho Lee, Junseok Bae, Han-Joong Keum

Department of Neurosurgery, Wooridul Spine Hospital, Seoul, Korea

Corresponding Author: Sang-Ha Shin Department of Neurosurgery, Wooridul Spine Hospital, 445 Hakdong-ro, Gangnam-gu, Seoul 06068, Korea Email: burrhoer@wooridul.co.kr

Received 2025 August 9; Revised 2025 October 27; Accepted 2025 October 28.

Abstract

INTRODUCTION

A bilateral or large central lumbar disc herniation can compress nerve roots on both sides and cause bilateral symptoms. Previous studies have shown that open microdiscectomy with bilateral laminectomy leads to favorable outcomes in cases of bilateral lumbar disc herniation with bilateral radiculopathy [1-5]. Transforaminal lumbar endoscopic discectomy (TELD) can also enable safely reaching the contralateral side for discectomy and decompression utilizing shallower approach angle and foraminoplasty [6-9]. Although open microdiscectomy is the established safe and effective surgical technique for bilateral disc herniation, the utilization for TELD for these cases can offer several advantages. TELD does not require bilateral laminectomy and theoretically, may reduce the risk of postoperative instability. Additionally, TELD can be performed under local anesthesia.

TELD, however, is an evolving alternative rather than an established gold standard in bilateral disc herniation. Despite the potential benefits, there is a lack of data in the current literature regarding the utility of unilateral TELD for bilateral discectomy and decompression. A few prior studies analyzed the outcomes of TELD for the treatment of large central disc herniation (half-moon shape) causing radiculopathy [10-13]. However, the cumulative data from these studies is still low and none of them focused on bilateral herniation (double-hump shape) causing bilateral symptoms. Although the approach to the disc space is similar, the surgical techniques for the 2 types of disc herniation differ. For large central disc herniation, the disc fragment can be removed after grasping the tail of the herniation and pulling on it. For double-humped disc herniation, ipsilateral discectomy is first performed followed by identification of the tail of the contralateral herniated fragment and its removal. The type of disc herniation and surgical techniques are demonstrated in Figure 1. The purpose of this study was to describe our TELD surgical technique for bilateral double-humped disc herniation with bilateral symptoms and report its outcomes.

Figure 1.

(A and B) Large central moon-shaped disc herniation. (C and D) Bilateral double-humped disc herniation.

MATERIALS AND METHODS

2. Surgical Technique

Schematic diagrams detailing the steps of the procedure are demonstrated in Figure 2. Steps under endoscopic visualization are shown in Supplementary Video Clip 1.

Figure 2.

Schematic diagrams illustrating the steps of transforaminal endoscopic lumbar discectomy for bilateral disc herniation. (A) Use of a shallower approach angle of 15° compared with the conventional 30°. (B) Foraminoplasty performed using a bone drill. (C) Removal of the ligamentum flavum. (D) Excision of the ipsilateral disc fragment. (E) Identification of the herniation route and dissection between the dura and the herniated mass. (F) Central decompression. (G) Removal of the contralateral disc fragment.

The patient was laid prone on a radiolucent table with Wilson frame with arms supported on arm boards over the head and legs hanging (Figure 3A). The operating room setup consisted of the surgeon standing on the side of the patient to be operated on, nurse and table with surgical instruments to the surgeon’s right, anesthesiologist towards patient’s head, and C-arm and video monitor in front of the surgeon (Figure 3B). The procedure was performed under local anesthesia. The anesthesiologist provided intravenous sedation and pain control with midazolam or fentanyl. The degree of sedation was controlled so that the patient could provide feedback during the procedure. The equipment included lumbar endoscope, C-arm, Holmium:YAG laser machine, endoscopy cart, and surgical instruments. The endoscope used was a 30° scope with outer diameter of 6.3 mm, working channel diameter of 3.7 mm, and 2 irrigation channels (TESSYS Std, Joimax GmbH, Germany). The endoscopy cart consisted of video monitor, light source, pump system for irrigation, control unit for camera and digital image processor, control unit for radiofrequency system, and drive unit and control unit for motorized instruments. Surgical instruments included instrument set for approach, endo-forceps, radiofrequency probe, dissector, bone drill, reamer, and endo-Kerrison.

Figure 3.

(A) Patient positioning. (B) Operating room setup. (C) Determination of the skin entry point by measuring the distance from the midline. (D) Epidurogram confirming the needle tip position. (E) Drilling of the ventral superior articular process. (F and G) Introduction of the working cannula.

The side of approach (left or right) was based on the location of the annular tear point and not the severity of the symptoms. For example, a left-sided approach would be performed in a patient with annular tear on the left side and more severe symptoms on the right side. The skin entry point was determined on preoperative axial magnetic resonance imaging (MRI) by calculating the distance from midline. This distance was approximately 12 to 16 cm, which is greater than that of a typical transforaminal approach (Figure 3C). The access angle was approximately 15° from the horizontal plane. The approach angle of 30° used in the conventional transforaminal approach can be difficult to obtain of the contralateral side. The craniocaudal trajectory was determined parallel to the disc space to provide the best working mobility during contralateral decompression. After determination of skin entry point and approach angle, an 18-gauge introducer needle was inserted under local anesthesia and advanced into the foramen. An epidural block was performed to reduce the pain during procedure. A radiopaque contrast was then injected to confirm the lateral margin of the dural sac and the location of the exiting nerve root (Figure 3D). The needle was pulled back and landed on the lateral edge of the superior articular process (SAP). The ventral part of the SAP was undercut using a serial bone reamer or endoscopic drill (Figure 3E) up to the medial pedicular line on the anteroposterior view. A working cannula was inserted along the reamed hole (Figure 3F and G) followed by introduction of the endoscope.

Laser and drill were used for removing the remnant osseous fragments and ligamentum flavum to expose the traversing nerve root and herniated disc (Figure 4A). A probe was used to dissect between the ipsilateral herniated disc and traversing root. The soft herniated disc was usually found anchored by fibrotic annular fissure. The annular anchorage was loosened by laser or scissors. After loosening the annular anchorage, ipsilateral herniated disc was removed with forceps (Figure 4B). After ipsilateral decompression, the annulus, posterior longitudinal ligament, and dura of the central zone were identified under the endoscopic view. The endoscope was now made more horizontal and central decompression was performed after dissecting between the herniated disc and dura with a probe. After central decompression, the endoscopic working cavity became wider and the undersurface of the contralateral annulus and the route of the contralateral herniated disc could be identified (Figure 4C). The contralateral herniation was removed using navigable or straight forceps (Figure 4D and E). Finally, the epidural pulsations were checked using the Valsalva maneuver and the decompressed ipsilateral traversing nerve root, central dura, and contralateral traversing nerve root could be directly visualized under the endoscope (Figure 4F). The working cannula and endoscope were then removed followed by closure with a single subcuticular suture.

Figure 4.

Sequential steps under endoscopic visualization. (A and B) Identification and removal of the ipsilateral disc herniation. (C) Identification of the contralateral disc herniation route (black asterisk). (D and E) Removal of the contralateral herniation. (F) Decompressed central dura and bilateral traversing nerve roots (NRs).

Patients could ambulate and got discharged within a few hours after surgery. Postoperative MRI was done for all patients as standard-of-care.

RESULTS

1. Demographic, Operative, and Perioperative Data

34 patients were included. The mean age was 41.6±10 years. 18 patients (52.9%) were male and 16 patients (47.1%) were female. The mean symptom duration was 19.5 (range, 6–52) weeks. L4–5 was the most commonly operated level (55.9%), followed by L3–4 (20.6%), L5–S1 (17.6%), and L2–3 (5.9%). The mean operative time was 58.0±22.1 (range, 38.0–112.0) minutes. The mean hospital stay was 1.2±0.4 (range, 1.0–3.0) days. The average follow-up duration was 9.6 (range, 6.0–12.0) months (Table 1).

Table 1.

Demographic, operative, and perioperative data

2. Clinical Outcomes

The mean preoperative VAS back was 5.8±2.5. VAS back significantly improved to 3.2±1.2 at 1 week, 2.2±1.2 at 1 month, and 1.8±0.9 at 6 months postoperatively (p<0.01 for all). The mean preoperative VAS leg was 7.2±1.6. VAS leg improved to 2.3±1.2 at 1 week, 1.7±1.1 at 1 month, and 1.5±0.9 at 6 months postoperatively (p<0.01 for all). The preoperative ODI was 58.2±21.7 which improved to 29.4±13.4 at 1 week, 22.0±10.6 at 1 month, and 14.5±9.6 at 6 months postoperatively (p<0.01 for all). The magnitude of improvement was substantial, with large effect sizes for all outcome measures at 6 months (VAS back d=2.08, VAS leg d=4.42, ODI d=2.51). These values of PROMs and effect sizes along with 95% confidence interval are summarized in Table 2.

Table 2.

Values of PROMs at the preoperative and 1-week, 1-month, and 6-month postoperative timepoints

4. Illustrative Cases

1) Case 1

A 41-year-old female presented with back pain and bilateral leg pain for 3 months that was not responding to conservative treatment. MRI showed a bilateral downmigrated transligamentous disc herniation at L4–5 (Figure 5A–D). TELD was performed which led to significant improvement in symptoms. Postoperative MRI done on the same day showed complete removal of bilateral disc herniation and adequate decompression (Figure 5E–H).

Figure 5.

A 41-year-old woman with back pain and bilateral leg pain for 3 months. (A–D) Magnetic resonance imaging (MRI) revealed bilateral downmigrated transligamentous disc herniation at L4–5. Transforaminal endoscopic lumbar discectomy led to significant symptomatic improvement. (E–H) Postoperative MRI demonstrated complete removal of the bilateral disc herniation and adequate decompression.

2) Case 2

A 52-year-old male presented with back pain and bilateral leg pain for 5 months that was not responding to conservative treatment. MRI showed bilateral upmigrated transligamentous disc herniation at L4–5 (Figure 6A–D). TELD was performed which led to significant improvement in symptoms. Postoperative MRI done on the same day showed complete removal of bilateral disc herniation and adequate decompression (Figure 6E–H).

Figure 6.

A 52-year-old man with back pain and bilateral leg pain for 5 months. (A–D) Magnetic resonance imaging (MRI) showed bilateral upmigrated transligamentous disc herniation at L4–5. Following transforaminal endoscopic lumbar discectomy, the patient experienced marked symptom relief. (E–H) Postoperative MRI confirmed complete removal of the bilateral disc herniation and sufficient decompression.

3) Case 3

A 78-year-old male presented with back pain and bilateral leg pain for 6 months that was not responding to conservative treatment. MRI showed bilateral subligamentous disc herniation at L4–5 (Figure 7A–D). TELD was performed which led to significant improvement in symptoms. Postoperative MRI done on the same day showed complete removal of bilateral disc herniation and adequate decompression (Figure 7E–H).

Figure 7.

A 78-year-old man with back pain and bilateral leg pain for 6 months. (A–D) Magnetic resonance imaging (MRI) demonstrated bilateral subligamentous disc herniation at L4–5. Transforaminal endoscopic lumbar discectomy resulted in substantial symptom improvement. (E–H) Postoperative MRI confirmed complete removal of the bilateral disc herniation and adequate decompression.

DISCUSSION

The current study attempted to analyze the outcomes of TELD for bilateral lumbar disc herniation causing bilateral radiculopathy. It was found that this technique led to significant improvement in symptoms by 1 week after surgery which was maintained up to the latest follow-up of 6 months. There were no intraoperative complications. Only 1 patient out of 34 required a reoperation for recurrent disc herniation.

Although open microdiscectomy has been shown to lead to favorable outcomes in cases of bilateral lumbar disc herniation with bilateral symptoms, TELD offers several benefits. Bilateral decompression through a unilateral approach with minimal bone removal is possible with TELD. Contrastingly, conventional microdiscectomy usually requires bilateral laminectomy and medial facetectomy for complete removal of bilateral disc herniation [4,5]. Additionally, decompression is possible with no or minimal nerve traction in TELD. The ipsilateral traversing root, central dura, and contralateral traversing root can all be visualized under the endoscope with no or minimal traction. In conventional microdiscectomy, retraction of the neural tissue is often required for completely removal of the fragments [11,12].

A few previous studies have compared the outcomes of endoscopic versus microscopic discectomy for large lumbar disc herniation. Hussein et al. [11] conducted a randomized controlled trial of 200 patients to compare the outcomes of microendoscopic discectomy (MED) versus open discectomy for large lumbar disc herniation. They found that the MED group had significantly lower intraoperative blood loss, shorter hospital stay, faster return to activities, and significantly greater improvements in back pain, leg pain, and disability at 8-year follow-up. However, it is important to note that MED utilizes a tubular retractor followed by introduction of the endoscope and hence is not a full-endoscopic technique. Additionally, this study only included patients with unilateral symptoms. Choi et al. [10] conducted a retrospective cohort study of 43 patients to compare outcomes of TELD and open microdiscectomy for large lumbar disc herniation. They found that the TELD group had significantly greater improvement in back pain and higher satisfaction rates than open microdiscectomy at 2 years. Additionally, there was a significant reduction in disc height following open microdiscectomy whereas the disc height did not change following TELD. However, whether the patients included had unilateral or bilateral symptoms was not specified in this study. Ren et al. [12] conducted a retrospective review of 26 patients who underwent unilateral TELD for bilateral radiculopathy secondary to lumbar disc herniation. Their surgical approach was similar to ours and they similarly reported significant improvement in back pain, leg pain, and disability after surgery. Li et al. [13] conducted a prospective randomized study of 71 patients to compare unilateral versus bilateral TELD for L3–4 or L4–5 disc herniation with bilateral symptoms. They reported that the unilateral approach had shorter operative time, less radiation exposure, and less postoperative back pain compared to bilateral approach.

Although prior reports have discussed endoscopic treatment for bilateral symptoms, they included different case-mix and techniques compared to the current study. Ren et al. [12] analyzed unilateral TELD for bilateral radiculopathy and showed that contralateral decompression could be performed through a unilateral approach. However, it is important to note that their cohort predominantly comprised large central herniations and did not focus on the bilateral “double-hump” morphology in which each paracentral zone is independently occupied by herniated material. Contrastingly, our cohort was deliberately restricted to true bilateral (double-humped) herniations, requiring identification and removal of both ipsilateral and contralateral fragments through a single transforaminal route. Li et al. [13], in their comparative study of unilateral versus bilateral TELD for bilateral symptoms, reported advantages of less operative time, radiation exposure, and postoperative back pain with unilateral approach without compromising clinical improvement. Our data serves to extend these observations to the technically more demanding double-humped pattern and demonstrates that a carefully planned unilateral TELD approach can still accomplish thorough bilateral decompression with significant improvements in VAS back/leg and ODI, minimal intraoperative complications, and low rates of postoperative dysesthesia and reherniation. Altogether, these comparisons signify that while prior studies established the feasibility of unilateral TELD for bilateral symptoms, the present study shows its effectiveness specifically for double-humped herniations using a standardized access strategy and stepwise contralateral reach.

The surgical technique utilized and cases included in the current study differ from the previous studies. Firstly, in the previous studies, the herniation was mostly central. In the current study, the disc herniation was located in the ipsilateral subarticular, central, and contralateral subarticular zones. Secondly, patients included in the previous studies mostly had half-moon-shaped large disc herniation. Contrastingly, the current study included bilateral herniations with double-humped shape or multiple fragments. Thirdly, in the current study, foraminal widening was performed to secure working mobility and access the contralateral side. Contralateral decompression was performed under direct visualization after making the endoscope more horizontal. Lastly, in the current study, approach was made from the side with the annular tear point and not based on the side with more severe symptoms. This was done to avoid making an iatrogenic annular tear and thus, reduce the chances of reherniation. Altogether, we describe a sequenced maneuver: (1) removal of the ipsilateral fragment after loosening of the annular anchorage, (2) central decompression with a more horizontal endoscope, and (3) targeted identification and removal of the contralateral fragment under direct endoscopic vision, confirming adequacy with epidural pulsations. Finally, we report uniform postoperative MRI on the day of surgery and short hospital stays with early ambulation, supporting the reproducibility and safety of this approach. Taken together, these elements represent a distinct, standardized uniportal TELD approach for double-humped bilateral disc herniations, complementing and refining the concepts introduced by Ren et al. [12] and Li et al. [13] while providing granular, technique-specific guidance for contralateral access through a single transforaminal route.

Six of the 34 cases (17.6%) in this study involved the L5–S1 level. All included L5–S1 cases had favorable lumbosacral anatomy characterized by low iliac crest or transitional segment, permitting the shallower 15° trajectory required for contralateral decompression. Developing the transforaminal corridor at L5–S1 for the usual unilateral paracentral herniation can often be difficult due to anatomical constraints such as iliac crest, sacral ala, transverse process, and hypertrophied facet. Further caution should be taken when selecting a patient with bilateral disc herniation at L5–S1 for TELD. Preoperative imaging should be adequately analyzed to ensure that the anatomy will allow a shallow angle of 15° with minimal craniocaudal angulation for bilateral disc access. Clinical outcomes and complication rates in the L5–S1 group were comparable to those at other levels, suggesting that with appropriate anatomical criteria, TELD can be safely performed at this level as well.

Limitations of the study include retrospective design, single-center data, low sample size (n=34), and lack of a control group. Single-center data and low sample size reduce the generalizability of the findings. The minimum follow-up required for inclusion in the study was 6 months and the average follow-up was 9.6 (range, 6.0–12.0) months. This short follow-up period limits the ability to assess the long-term efficacy and durability of the procedure as well as long-term reherniation rates, necessitating future studies with longer follow-up. In our study, the mean hospital stay was 1.2 days. However, it is important to note that TELD is a short procedure performed under local anesthesia and patients can be usually discharged the same day after a few hours of observation. In our setting, patients usually prefer to stay overnight due to factors such as distance from the hospital and hesitance to be discharged the same day. Although 18% of patients had L5–S1 as the operated level, it is important to note that most of these patients had transitional lumbosacral anatomy and low iliac crest. Despite the limitations, this is a relatively new technique and there is a lack of supporting evidence in the literature. We believe that the current study serves to fill this gap in the literature and lays the background for future cohort studies with longer follow-up to confirm the safety and efficacy of TELD for bilateral disc herniation.

CONCLUSION

TELD for bilateral lumbar disc herniation and bilateral radiculopathy led to favorable clinical outcomes with minimal complication rates. It can be a less invasive, safe, and effective surgical option for such cases. However, larger multicenter studies with longer follow-up are required to establish these findings and confirm long-term durability and recurrence rates after TELD for bilateral disc herniation.

Supplementary Material

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