The “Laminar Lifting” Technique for Full-Endoscopic Discectomy of Highly Upmigrated Herniation in Lytic Spondylolisthesis: A Technical Note and Report of 3 Cases

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

doi:10.21182/jmisst.2025.02523

Abstract

Full-endoscopic surgery for highly upmigrated lumbar disc herniation often requires foraminotomy or laminotomy. However, in the presence of lytic spondylolisthesis, the “laminar lifting” technique can be used to directly access the highly upmigrated fragment without bone removal. We report 3 cases of recent-onset radiculopathy caused by highly upmigrated disc herniation with concurrent lytic spondylolisthesis. The affected level was L5–S1 in two cases and L4–5 in one case. Interlaminar endoscopic lumbar discectomy was performed at L5–S1, and transforaminal endoscopic lumbar discectomy at L4–5. After gaining access to the epidural space, the working cannula was depressed at its proximal end, thereby elevating its distal end. This maneuver produced a levering effect that lifted the lamina and created additional space in the epidural area. The working cannula could then be advanced further superiorly, allowing removal of the highly upmigrated disc fragment with endoscopic forceps. All patients had excellent outcomes without complications. These findings demonstrate that the “laminar lifting” technique is a safe and effective method for full-endoscopic removal of highly upmigrated disc herniation in the setting of lytic spondylolisthesis. It eliminates the need for bone removal and helps prevent further instability in lytic spondylolisthesis.

Key Words: Lytic spondylolisthesis, Isthmic spondylolisthesis, Disc herniation, Endoscopic discectomy, Foraminoplasty

INTRODUCTION

Disc herniation is a common pathology of the lumbar spine. It is mostly paracentral in location and can cause radiculopathy due to compression of nerves. The herniated fragment can sometimes migrate superiorly or inferiorly after rupturing the posterior longitudinal ligament. The radiological classification system devised by Lee et al. [1] assesses the degree of disc migration with respect to the pedicle. Surgery for highly upmigrated disc herniation can pose some challenges. Open surgery for these cases may require significant removal of lamina, pars interarticularis, and facet, thereby increasing the risk of iatrogenic instability [2]. Full-endoscopic surgery for highly upmigrated disc herniations can be technically challenging and often requires foraminoplasty or translaminar approach to access migrated fragment [3,4]. However, in presence of lytic spondylolisthesis, “laminar lifting” technique can be utilized to directly access the highly upmigrated herniation by creating more space for the working cannula in the epidural space. This technique obviates the need for bone removal and avoids further increasing the risk of instability in lytic spondylolisthesis. It takes the advantage of the flexibility of the posterior column due to pars defect and has not been described in the literature before. We hereby report 3 cases of lytic spondylolisthesis presenting with recent-onset radiculopathy due to highly upmigrated disc herniation where “laminar lifting” technique was successfully utilized for full-endoscopic discectomy without bone removal. Unlike previously described translaminar and foraminoplasty techniques that require bony removal to visualize the upmigrated fragment, our “laminar lifting” approach leverages the mobility conferred by pars defect in cases of lytic spondylolisthesis. By gently depressing the proximal end of the working cannula, the distal end functions as a lever to elevate the lamina and create space for superior advancement of the cannula without bony resection. This preserves the integrity of the posterior elements and therefore prevents further risk of instability in such cases.

CASE REPORTS

1. Case 1

A 46-year-old lady presented with radiating pain along lateral aspect of right thigh and calf for 6 weeks. It was associated with numbness and tingling. There was no back pain or urinary incontinence. Examination revealed intact power and decreased sensations in right L5 distribution. Symptoms were refractory to conservative measures including medications and physical therapy. Magnetic resonance imaging (MRI) revealed right paracentral highly upmigrated disc herniation at L5–S1 (Figure 1A and B). Plain radiographs and computed tomography revealed lytic spondylisthesis at L5–S1 (Figure 1C and D). Since the complaint was radiating leg pain for 6 weeks and the patient had been asymptomatic previously, it was decided to address only the acute disc herniation and not the chronic lytic spondylolisthesis. After discussion with the patient, interlaminar endoscopic lumbar discectomy (IELD) was performed under local anesthesia. Postoperative MRI showed complete removal of disc herniation and adequate decompression (Figure 1E and F).

2. Case 2

A 30-year-old gentleman presented with left L5 radiculopathy for 1 month. There was no back pain, motor deficit, or urinary incontinence. Imaging revealed left paracentral highly upmigrated disc herniation along with lytic spondylolisthesis at L5–S1 (Figure 2A–D). Similar to case 1, this patient complained of recent-onset leg pain and had been asymptomatic before. Upon failure of conservative treatment, IELD was performed under local anesthesia. Postoperative MRI showed complete removal of disc herniation and adequate decompression (Figure 2E and F).

3. Case 3

A 57-year-old gentleman presented with right L4 radiculopathy for 2 months. There was no back pain, motor deficit, or urinary incontinence. Imaging revealed right paracentral highly upmigrated disc herniation along with lytic spondylolisthesis at L4–5 (Figure 3A–D). Similar to cases 1 and 2, this patient complained of recent-onset leg pain and had been asymptomatic before. Upon failure of conservative treatment, transforaminal endoscopic lumbar discectomy (TELD) was performed under local anesthesia. Postoperative MRI showed complete removal of disc herniation and adequate decompression (Figure 3E and F).

4. Surgical Technique

1) Interlaminar endoscopic lumbar discectomy

Patient was laid prone on radiolucent table with Wilson frame under intravenous sedation and pain control. Midline, medial pedicular line, and interlaminar space were marked on anteroposterior (AP) fluoroscopic view. The caudocranial angulation was determined on the lateral view according to the laminar slope. After determination of the skin entry point, local infiltration with 1% lidocaine was done. An 18-gauge spinal needle was then inserted with the most lateral area of interlaminar space and posterior L5 vertebral border as targets on AP and lateral views, respectively (Figure 4A and B). This is considered as the safe area for needle entry. The needle was advanced into the epidural space and an epidurogram was done to confirm safe position of the needle tip between thecal sac and exiting root (Figure 4C). A guidewire now replaced the needle. Sequential dilators were inserted. This was followed by the introduction of the working cannula and endoscope (Figure 4D and E). The endoscope used was a 30° scope with working length of 125 mm, outer diameter of 6.3 mm, working channel diameter of 3.7 mm, and 2 irrigation channels (iLESSYS, Joimax GmbH, Germany). Under endoscopic visualization, the herniated fragments were identified and removed in a piecemeal fashion with endoscopic forceps (Figure 4F and G). The hand holding the working cannula and endoscope was pushed down. This pulled up the distal end of the working cannula and lifted the lamina with the levering effect. This maneuver more space in the epidural space for the working cannula to be advanced superiorly towards the highly upmigrated fragment (Figure 4H). The levering effect was possible because of the pars defect that rendered flexibility to the posterior column. The highly upmigrated fragment could now be visualized and removed with endoscopic forceps (Figure 4I and J). The demonstrated steps in Figure 4 are from case 1.

2) Transforaminal endoscopic lumbar discectomy

Patient was laid prone on a radiolucent table with Wilson frame under intravenous sedation and pain control. The distance of the skin entry point from midline was determined on preoperative MRI by drawing a line starting from the target point, passing lateral to the facet, and extending to the skin (Figure 5A). The caudocranial trajectory was determined on the lateral fluoroscopic view (Figure 5B). After local infiltration with 1% lidocaine, an 18-gauge needle was inserted and landed on the facet (Figure 5C). It was then directed superiorly to gain entry into the epidural space. An epidurogram was done. The needle was advanced parallel to the exiting root up to the posterior vertebral border (Figure 5D and E). Sequential dilators were inserted. This was followed by introduction of the working cannula. After entry into the foramen, the proximal end of the working cannula was pushed down with the hand holding it so that the distal end could be pulled up. This maneuver lifted the lamina due to levering effect and enlarged the foramen. The working cannula was then advanced further (Figure 5F and G). The endoscope was now introduced. It was a 30° scope with working length of 171 mm, outer diameter of 6.3 mm, working channel diameter of 3.7 mm, and 2 irrigation channels (TESSYS Std, Joimax GmbH). Under endoscopic visualization, herniated fragments were removed in piecemeal fashion with endoscopic forceps (Figure 5H and I). After partial removal, the highly upmigrated fragment could be visualized and was removed with endoscopic forceps (Figure 5J–L).

5. Outcomes

There were no intraoperative complications. Patients reported significant reduction in pain immediately after the surgery and could ambulate within a few hours. Postoperative hospital stay was uneventful and all patients were discharged the same day. At the latest follow-up (case 1: 6 years; cases 2 and 3: 2 years), patients continued to do well and were symptom-free. There were no postoperative complications or reoperations.

The patients were informed that data concerning their cases would be submitted for publication, and they provided consent.

DISCUSSION

The utilization of full-endoscopic lumbar discectomy has been increasing because of potential advantages such as less invasiveness, lower postoperative pain, and faster recovery over open microdiscectomy [5-11]. However, full-endoscopic surgery can be challenging in cases with highly migrated disc herniation. Various endoscopic techniques have been described by previous studies for removal of upmigrated disc herniations [2]. Foraminoplasty is often required to access the migrated fragment and widen the range of endoscopic visualization in the epidural space. A translaminar approach has been described by recent reports for removal of highly upmigrated disc herniation. This approach involves making a laminar fenestration to directly access the disc fragment.

Previously, several reports have discussed the endoscopic surgical technique for the removal of highly migrated lumbar disc herniations. Choi et al. [2] and Kim et al. [3] demonstrated that bone resection through foraminoplasty or translaminar drilling was often necessary to access the migrated fragment and prevent incomplete decompression. Zhang et al. [12] and Khandge et al. [13] each reported a case of highly upmigrated disc herniation at L4-5 where full-endoscopic translaminar discectomy was successfully performed. Lin et al. conducted a retrospective study to analyze the outcomes of full-endoscopic translaminar discectomy for highly upmigrated disc herniation [14]. Their findings demonstrated significant clinical improvement with excellent/good outcomes in 92% of patients. Previously, Kaneko et al. [15] reported a case of upmigrated disc herniation with lytic spondylolisthesis at L5–S1 successfully treated by IELD. However, their technique included carving out the medial border of the lamina using a drill as the working cannula could not reach the intended apex of the herniation. We believe that although foraminoplasty or laminar fenestration are necessary to access a highly upmigrated herniation in usual cases, they are not required in presence of lytic spondylolisthesis where the posterior column is flexible due to pars defect. As described, the working cannula when pushed down lifts the lamina due to levering effect. This creates more space for the working cannula to be advanced superiorly towards the highly upmigrated disc fragment. Whereas the previously described translaminar keyhole and foraminoplasty techniques widen access by fenestrating lamina or drilling the foramen, respectively, the “laminar lifting” technique achieves the same working corridor by controlled laminar elevation mediated by the cannula’s levering effect in the setting of a pars defect—no laminotomy or foraminotomy is required. Cases with lytic spondylolisthesis are already prone to instability and removing bone in the posterior column can further aggravate this risk. In usual cases with intact pars and posterior column, the only way to enable the visualization and accessibility of the highly upmigrated disc fragment is bone removal in the form of foraminotomy or laminotomy.

Approach selection is vital. We usually prefer TELD over IELD for lumbar disc herniation. This is because TELD is less invasive than IELD as it approaches the disc space directly via the foramen bypassing vital posterior structures. However, TELD at L5–S1 can often be difficult due to restricted transforaminal access resulting from high iliac crest, transverse process, hypertrophied facets, and sacral ala. In such cases, we prefer to perform IELD. In cases 1 and 2 in this report, the disc herniation was at L5–S1 and TELD would have required taking a craniocaudal approach due to the iliac crest. This would have directed the working cannula and endoscope away from the highly upmigrated disc. In this scenario, completely removing the disc fragment would have been technically very challenging. IELD, on the other hand, takes a caudocranial direction. The wide interlaminar window at L5–S1 enabled making an interlaminar approach and the pars defect rendered more mobility to the working cannula facilitating its advancement up to the superior extent of disc herniation by lifting the lamina using levering effect. Case 3, on the other hand, had a highly upmigrated disc herniation at L4–5 where, unlike cases 1 and 2, the iliac crest was not restricting a caudocranial transforaminal angle. After accessing the disc via the foramen, the lamina could be lifted because of the pars defect and the working cannula could be advanced superiorly to completely remove the highly upmigrated disc herniation. In the techniques previously described by Zhang et al. [12], Khandge et al. [13], and Lin et al. [14], laminar fenestration was required to access high-grade upmigrated fragments, with favorable short-term clinical improvement. In the IELD technique described by Kaneko et al. [15] for isthmic spondylolisthesis at L5–S1, drilling of the medial lamina was required to reach the upmigrated fragment. Contrastingly, in our 3 cases, the fragment was accessed and removed without laminotomy or foraminoplasty, using controlled laminar elevation through the levering effect of the working cannula. At 2–6 years’ follow-up, there were no reoperations and patients remained symptom-free.

Since these cases require working in the epidural space, caution should be exercised to not injure the dura or nerves. The procedure is performed under direct endoscopic visualization with the cannula maintained tangential to the dura and traversing root. Graded proximal depression of the working cannula is done to achieve laminar elevation; abrupt excursions are avoided. Epidural venous bleeding is controlled with radiofrequency coagulation; hemostatic agents can be used as needed. The trajectory is planned to keep the working cannula parallel to the neural elements and to avoid placing the tip directly against the dura. These steps reduce the risk of inadvertent dural or nerve injury during the procedure. In lytic spondylolisthesis, the pars defect imparts relative flexibility to the posterior arch. Our “laminar lifting” technique intentionally applies a low-amplitude levering force via the working cannula to temporarily elevate the lamina, increasing the epidural working space. Since no posterior element is resected and the posterior tension band is preserved, further destabilization is theoretically avoided. Nevertheless, it is important to highlight that repeated or excessive levering could increase local micromotion at the pars defect site. Biomechanical studies are required in this regard to quantify the magnitude of laminar excursion and the force thresholds that can be applied within safe limits.

This study has several limitations. The sample size is small (n=3) restricting the generalizability of the findings. There is a lack of comparative data with other established techniques and biomechanical assessment to objectively validate the safety and reproducibility of the “laminar lifting” technique. It is important to note that the present report primarily only focuses on the technical feasibility and surgical nuances of this novel approach. Future research including larger cohorts, objective biomechanical testing, and systematic outcome assessment is required to better define the role, safety thresholds, and long-term efficacy of this technique.

CONCLUSION

“Laminar lifting” technique is a safe and effective technique for full-endoscopic removal of highly upmigrated disc herniation in presence of lytic spondylolisthesis. It takes the advantage of a flexible posterior column and creates more space in the epidural space by lifting the lamina using levering effect. It obviates the need for bone removal to reach the migrated fragment and hence, prevents further increasing the risk of instability in lytic spondylolisthesis.

NOTES

Conflicts of interest

The authors have nothing to disclose.

Funding/Support

This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Figure 1.

Case 1. (A–D) Imaging revealed a right paracentral, highly upmigrated disc herniation with lytic spondylolisthesis at L5–S1. (E and F) Postoperative magnetic resonance imaging demonstrated complete removal of the herniated fragment and adequate decompression.

Figure 2.

Case 2. (A–D) Imaging revealed a left paracentral, highly upmigrated disc herniation with lytic spondylolisthesis at L5–S1. (E and F) Postoperative magnetic resonance imaging demonstrated complete removal of the herniated fragment and adequate decompression.

Figure 3.

Case 3. (A–D) Imaging revealed a left paracentral, highly upmigrated disc herniation with lytic spondylolisthesis at L4–5. (E and F) Postoperative magnetic resonance imaging demonstrated complete removal of the herniated fragment and adequate decompression.

Figure 4.

Surgical technique of interlaminar endoscopic lumbar discectomy for highly upmigrated disc herniation. After determining the skin entry point, an 18-gauge spinal needle was inserted under fluoroscopic guidance, targeting the most lateral region of the interlaminar window on the anteroposterior view (A) and the posterior vertebral border on the lateral view (B). (C–E) After entering the epidural space, an epidurogram was performed to confirm safe needle positioning. (D and E) Sequential dilators, the working cannula, and the endoscope were then introduced. (F and G) Under endoscopic visualization, the herniated fragments were identified and removed piecemeal. (H) The lamina was lifted by the levering effect, allowing the working cannula to advance further superiorly. (I and J) The highly upmigrated disc fragment was visualized and removed.

Figure 5.

Surgical technique of transforaminal endoscopic lumbar discectomy for highly upmigrated disc herniation. (A) The distance from the skin entry point to the midline was determined on preoperative magnetic resonance imaging. (B) The caudocranial trajectory was planned on the lateral fluoroscopic view. An 18-gauge needle was inserted to contact the facet (C), then directed superiorly to enter the foramen and advanced parallel to the exiting nerve root up to the posterior vertebral border (D and E). (F and G) The working cannula and endoscope were inserted. (H and I) Under endoscopic visualization, the herniated fragments were identified and removed piecemeal. (J–L) After partial removal of the herniation, the highly upmigrated fragment became visible and was excised.

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