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CC BY-NC-ND 4.0 · Asian J Neurosurg
DOI: 10.1055/s-0045-1812016
Original Article

“Across-the-Top” Biportal Endoscopic Spinal Surgery for Right-Sided Pathologies: Technical Note

Authors

  • Mohammad A. Ansari

    1   Department of Neurosurgery, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India

  • Faiz K. Yusufi 

    2   Department of Surgery, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
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Abstract

Background

Unilateral biportal endoscopic (UBE) spine surgery has become a promising minimally invasive technique for treating lumbar spinal pathologies, offering advantages such as reduced blood loss, minimal tissue disruption, and faster recovery. The “across-the-top” technique, a contralateral decompression approach, effectively treats right-sided lumbar lesions while preserving midline stabilizing structures. This study evaluates this technique's surgical methodology, safety, and clinical outcomes in patients with exclusive right-sided spinal pathology.

Materials and Methods

This prospective observational study included 24 patients presenting with exclusive right-sided lumbar spinal pathologies, such as ligamentum flavum hypertrophy or disc herniation with radiculopathy and/or numbness, who met the inclusion criteria. All patients underwent UBE decompression using the “across-the-top” technique after informed consent. Surgeries were performed under general anesthesia in the prone position, with the surgeon positioned on the patient's left side. Two right paramedian skin incisions were made to establish the endoscopic (cranial) and working (caudal) portals. Port docking was performed at the lower vertebral pedicle and 3 cm cranially, guided by C-arm fluoroscopy. Paraspinal muscle dissection and bony decompression were performed using an RF probe and high-speed drill. The ligamentum flavum was excised to expose neural elements, with decompression confirmed by visualization of the epidural space. Hemostasis was achieved, and a drain was placed before wound closure. All patients were followed for 3 months postoperatively to assess outcomes and complications.

Results

All surgeries were completed successfully without intraoperative complications. No patient experienced dural tears, nerve root injury, or infections. Only two patients had residual numbness at 3 months; all others had significant symptomatic relief. Most were discharged on postoperative day 2.

Conclusion

The “across-the-top” UBE technique is a safe, effective, and ergonomic technique for right-sided lumbar pathology, providing excellent decompression while preserving stabilizing structures and ensuring rapid recovery.


 

Keywords

UBE - lumbar canal stenosis - decompression - minimally invasive surgery

Introduction

Unilateral biportal endoscopic (UBE) surgery has emerged as an alternative to the traditional techniques of open or tubular techniques for spinal pathologies like disc herniation or stenosis. Endoscopic spine surgery relocates the point of visualization from the surgeon's eye or microscope to the precise location of the spinal pathology using an endoscope.[1] UBE allows visualization of the spinal structure via two small incisions on the paramedian locations; therefore, it carries several advantages as compared to its counterparts, like percutaneous endoscopic surgery or open surgery, such as better visualization, less intraoperative blood loss, less postoperative pain, early postoperative recovery, and better postoperative stability.[2] [3] [4] Due to these advantages, UBE adoption has increased steadily nowadays. Mastering the technique of UBE requires specialized training and equipment, making it challenging for beginners due to its steep learning curve. Additionally, there is a potential risk of complications, like nerve damage, dural tears, postoperative hematoma, and infections.[5]


 

Material and Methods

The patient with exclusive right-sided pathology was included in the study after proper informed consent. The main indication of the surgery was: (1) ligamentum flavum hypertrophy with isolated Right side symptoms, including radiculopathy and/or numbness. (2) Right side disc herniation, including upward/downward with or without migration. (3) Patients with numbness have symptoms after 6 months. The “across-the-table technique” was applied to all these patients. All the patients were followed up for 3 months.

A total of 24 patients were included in the study.


 

Methods of Surgery

UBE is used for various indications, but we have used this “across-the-top” technique for patients with exclusive right-sided pathologies. The technique is performed under general anesthesia in the prone position. The surgeon stands on the left side of the prone patient. Two horizontal skin incisions are given in the right paramedian position, midway between the medial pedicle line and the spinous process. Port creation is done at the pedicle line at the lower vertebral body and 3 cm above it. The C-arm is used to guide the target disc space. The two ports' docking point is the superior lamina's lower margin. Two ports, one being cranial and an endoscopic port, and the caudal one is a working port, also known as inflow and outflow ports, respectively. Serial dilatators dilate the incision and reach the spinous laminar junction. Paraspinal muscle dissection around the lamina using the ablation mode of an RF probe and saline irrigation through an endoscopic port to the working portal helps maintain a clear working space. The outer layer of LF is removed to confirm the landmark of the laminectomy.


 

Visualization and Decompression

Right-sided laminotomy, that is, drilling of the inferior margin of the upper vertebra, using a drill, is done until the upper edge of the ligamentum flavum is visualized. This is completed when we can identify the cranial epidural space. Bone removal is done until all the margins, that is, upper, lateral, and inferior, are visible. This is followed by removing the right-sided ligamentum flavum from its inferior attachment. LF is removed from all sides to expose the disc and neural elements, which is then followed by additional removal of bone if required for more decompression. The endpoint of surgery is nerve decompression. After sufficient decompression, hemostasis is achieved, and a drain is inserted through the instrument portal. After that, the muscles are approximated, and the skin is closed.


 

Results

Illustrative Case

A 45-year-old/male presented with complaints of Rt Lower limb pain for the last 8 months. On clinical evaluation, the patient had the power of 5/5 in Rt lower limbs with SLR +ve on Rt side at 45 degrees. The rest of the clinical assessment was within normal limits. On Imaging, Diffuse postero-lateral disc protrusion was noted at L4/L5 and L5/S1 intervertebral levels, indenting the thecal sac and narrowing it with bilateral nerve root compression (more at L4/L5 level with Rt > Lt; [Fig. 1A], [B]).

Zoom
Fig. 1 (A, B) Diffuse postero-lateral disc protrusion was noted at L4/L5 and L5/S1 intervertebral levels, indenting the Thecal sac and narrowing it with bilateral nerve root compression (more at L4/L5 level with Rt > Lt).

Bilateral nerve and mild degenerative changes were noted in the form of disc desiccation and marginal osteophyte formation at various corners of the lumbar vertebrae. The “across the table” technique was used to operate on the patient. After painting and draping, L4/L5 levels are marked in the prone position, followed by endoscopic and working port creation. Paraspinal disc space was created, which was followed by drilling of the L4 pedicle and the ligamentum flavum excision ([Fig. 2A]–[D]). The sac and the nerve roots are decompressed, and hemostasis is achieved ([Fig. 2E]).

Zoom
Fig. 2 (A) Lower part of the cranial lamina being nibbled by Kerrison punch. (B) The midline central cleft is being visualized. (C) Nerve root being exposed after a limited flavectomy. (D) Disc being removed after retraction of the nerve root with the hook. (E) Annuloplasty is being done with an RF wand.

All 24 patients included in the study had uneventful surgery. There was no dural injury, no nerve root injury. None of the patients had any infection over the follow-up period. All the patients were discharged on postoperative day 2. Only two patients who were operated on for numbness had some symptoms after 3 months. The rest of the patient did not have any complaints.


 

 

Discussion

In recent years, UBE spinal surgery has gained acceptance. It has emerged as a better tissue-sparing alternative to conventional open techniques for managing lumbar spinal pathologies.[6] [7] The “across-the-top” technique, as used in our case, further enhances the utility of UBE by allowing effective contralateral decompression through a unilateral approach without repositioning the surgeon or compromising midline structures. One of the critical considerations in this technique is the deliberate choice not to place the incision on the left (ipsilateral) side when operating on right-sided pathologies.[8] [9] Doing so would necessitate crossing through or removing significant portions of the posterior midline structures, such as the base of the spinous process, the interspinous ligament, and the adjacent musculature. Disruption of these stabilizing structures could lead to increased postoperative pain, instability, and significant muscle weakness, especially in patients already compromised by chronic compression.[10] [11] [12] [13]

Using a right-sided paramedian approach and working “across-the-top” to reach the contralateral side, we preserve these essential elements, enhancing postoperative outcomes and maintaining spinal integrity. Second, a significant ergonomic advantage of this approach lies in not altering the surgeon's position during the procedure. Most spine surgeons are right-handed, and the standard UBE setup places the working portal in the surgeon's dominant (right) hand and the endoscopic viewing portal in the left hand. Standing on the patient's left side for a right-sided pathology maintains this optimal orientation.[14] If the surgeon were to stand on the right side, attempting the same approach would reverse the hand dynamics, leading to inefficient instrument handling and potentially increased operative time or risk of error in the initial stages. Preserving the surgeon's default positioning ensures a more intuitive and controlled surgical flow, especially in high-precision procedures like endoscopic decompression. Our illustrative case reinforces the efficacy of this technique. The patient experienced symptomatic relief and neurological improvement without perioperative complications. These findings are consistent with the literature supporting UBE's favorable outcomes, including decreased blood loss, reduced postoperative pain, quicker recovery, and lower complication rates.[8] [9] [10] [14]

Nevertheless, the “across-the-top” technique demands a solid understanding of contralateral anatomy, proficiency with endoscopic tools, and refined motor coordination.[1] Mastery comes with dedicated training and experience. Furthermore, while complication rates are low, risks such as dural tears, neural injury, and infection remain and must be diligently guarded against.


 

Conclusion

The “across-the-top” UBE approach is safe, effective, and ergonomically advantageous for contralateral decompression in lumbar spine surgery. It offers distinct advantages in terms of tissue preservation and surgical comfort, especially when tailored to the anatomy and dominant hand of the right-handed surgeon. Future studies comparing this technique with other minimally invasive strategies will further clarify its role in spine surgery.


 

 

Conflict of Interest

None declared.


Address for correspondence

Faiz K. Yusufi, MBBS, MS, MRCS
Department of Surgery, Jawaharlal Nehru Medical College, Aligarh Muslim University
Aligarh 202001, Uttar Pradesh
India   

Publication History

Article published online:
25 September 2025

© 2025. Asian Congress of Neurological Surgeons. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

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Zoom
Fig. 1 (A, B) Diffuse postero-lateral disc protrusion was noted at L4/L5 and L5/S1 intervertebral levels, indenting the Thecal sac and narrowing it with bilateral nerve root compression (more at L4/L5 level with Rt > Lt).
Zoom
Fig. 2 (A) Lower part of the cranial lamina being nibbled by Kerrison punch. (B) The midline central cleft is being visualized. (C) Nerve root being exposed after a limited flavectomy. (D) Disc being removed after retraction of the nerve root with the hook. (E) Annuloplasty is being done with an RF wand.