Expanding the Possibilities of the Endoscopic Contralateral Approach—2-Level Decompression Using a Single Biportal Approach for Double Crush Root Syndrome: Technical Note and Feasibility

Cheol Wung Park; Parvez Shamim; Chai-Min Yoo; Jacob Yoong-Leong Oh

doi:10.21182/jmisst.2024.01781

Abstract

Patients with degenerative lumbar spinal stenosis and double crush syndrome often require decompression of the nerve root at multiple levels. Traditional approaches are limited by the need for extensive bony resection and the risk of iatrogenic instability. The endoscopic contralateral approach offers a minimally invasive alternative, but has primarily been applied to single-level decompressions. This study evaluated the feasibility of an "extended" biportal endoscopic contralateral approach for 2-level decompression in a patient with double crush syndrome, detailing the surgical technique and outcomes. A 69-year-old female patient presented with bilateral leg pain and numbness attributed to severe stenosis at L4–5 and L5–S1. The patient underwent a single biportal endoscopic procedure utilizing an extended contralateral approach to decompress the L4–5 central canal, lateral recess, and the L5–S1 foramen. The technique involved careful planning of incision placement, sublaminar drilling, and decompression of the L5 nerve root across both levels. The second illustrative case is a patient with L4 double crush syndrome who was managed similarly. Postoperative imaging demonstrated successful decompression of the L4–5 central canal and L5–S1 foramen, with preservation of the L5 pars interarticularis. The patient experienced complete symptom resolution. The approach resulted in minimal soft tissue dissection and bony preservation, enhancing surgical efficiency. The extended biportal endoscopic contralateral approach effectively addresses double crush root syndrome through a single minimally invasive approach. This technique improves operating room efficiency, while still achieving good neural decompression without causing iatrogenic instability, and may be a viable surgical option for selected cases.

Key Words: Endoscopy, Decompression, Spinal stenosis

INTRODUCTION

Double crush syndrome, first introduced by Upton and McComas [1] in 1973, describes a scenario in which peripheral nerves are compromised at multiple points along their path, leading to amplified symptoms such as radiculopathy, pain, and neurological deficits. This concept has been widely recognized in clinical practice, particularly for the lumbar nerve root, where nerve compression can occur at the foraminal and extraforaminal zones. These compressions may arise from conditions like disc herniation, foraminal stenosis, or degenerative changes, contributing to the "double crush" phenomenon [2]. Traditional surgical approaches often necessitate wide dissection and bilateral exposure, which carry the risk of increased postoperative complications, extended recovery periods, and significant muscle trauma [3]. A major challenge when treating patients with foraminal pathology is decompressing the nerve root without causing iatrogenic instability. Therefore, finding a minimally invasive alternative is crucial. With the advancement of endoscopic surgery, decompression of the central canal, lateral recess and foraminal stenosis can be performed concurrently using a single approach through the endoscopic contralateral approach [4,5]. However, these techniques are traditionally limited to decompressing the canal and exiting root at same level for 2 separate roots, which differs from the pathology of double crush syndrome.

In this article, we highlight 2 cases of double crush syndrome – A patient presenting with L5 double crush syndrome was treated with an “extended” contralateral approach. Here, the L4–5 central canal, along with the lateral recess and L5–S1 foramen were decompressed using a single biportal approach, to free the L5 nerve root across 2 levels. The patient had complete resolution of symptoms and postoperative imaging showed good decompression with preservation of the L5 pars interarticularis. The second case is a patient presenting with an L4 double crush syndrome and managed similarly. Our surgical technique is described in detail as below.

CASE ILLUSTRATION 1

A 69-year-old woman presented with symptoms of bilateral leg pain (right > left) and numbness radiating from her buttock, posterior thigh and calf for the past 6 months. The visual analogue scale (VAS) score was 7, and her symptoms had progressed without improvement despite conservative management. Clinical examination was unremarkable, and she had full sensation and motor power of all myotomes. X-rays showed degenerative changes without any signs of instability. The magnetic resonance imaging (MRI) of the lumbar spine revealed severe central canal and lateral recess stenosis at L4–5, and foraminal stenosis from a disc herniation at L5–S1 (Figure 1). She underwent a successful biportal decompression using an “extended” contralateral approach to decompress the L4–5 central canal, lateral recess, and L5–S1 right foramen using a single approach. She had complete resolution of symptoms postoperatively. Informed consent was obtained from the patient for academic reporting.

SURGICAL TECHNIQUE

1. Localization and Incision

The patient was positioned prone under sedation with regional anesthesia. The surgeon stands on the patient's left side. A spinal needle was used to localize the working portal, formed by the intersection between the medial pedicular line and the upper half of the L5 pedicle. A second incision is then made for the endoscopic portal, situated 2–3 cm above the working port. In this case, the ports were placed more caudal, just at the inferior edge of the pedicle (blue circle), to allow for an optimal trajectory and working space to visualize the opposite L5 exiting nerve root (Figure 2).

2. Biportal Central and Lateral Recess Decompression of L4–5

We started the procedure with a central canal and lateral recess decompression of L4–5. After the incisions were made, the 0° endoscope is introduced. Saline irrigation with a gravity pump was used. The spinolaminar junction is identified for anatomical reference. Following this, a laminotomy was performed on the ipsilateral side, followed by the contralateral area. The authors prefer an en bloc removal of the ligamentum flavum as the flavum acts like a safety barrier for the dura while introducing our instruments [6]. Targeting the attachments of the flavum during drilling is essential. Removing the right amount of bone facilitates a smooth and complete en bloc removal of the flavum in one attempt. Once the laminotomy is complete and the flavum is isolated and detached, it was removed in 2 large pieces with a pituitary rongeur.

3. “Extended” Contralateral Decompression (for L5–S1 Foraminal Stenosis)

The “extended” contralateral approach started with a laminotomy on the upper portion of L5. Specifically, bone was removed from the ipsilateral L5 lamina and midline (upper part of spinous process). This improves visualization for contralateral sublaminar drilling and decompression of the right exiting nerve root (Figure 3A-C). Overzealous bony resection in the sublaminar “tunnel” must be avoided to prevent an iatrogenic pars defect. Care must also be taken at all times as this area is deficient from a protective layer of flavum under the bone. We prefer to use a 4mm diamond burr instead of a shaver as it is low profile and more gentle on soft tissue. Drilling follows the path of the L5 nerve root. Landmarks guiding us to the foramen included seeing and palpating the medial/inferior wall of the L5 pedicle and Kambin triangle, just inferior to the L5 root. Visualization of the entire root is shown in (Figure 4).

Once within the foramen, a 30° endoscope was used for better visualization. Angled instruments facilitated a better reach within the “tunnel.” A C-arm is confirmed positioning, and a discectomy was performed. A foraminoplasty (partial resection of the superior articular process tip and flavectomy) was also carried out to give more space for the L5 exiting root. Hemostasis was secured, a drained inserted and the wound closed in layers. Postoperative MRI showed good decompression of L4–5 and no residual compression at the L5 foramen (Figure 5).

CASE ILLUSTRATION 2 (L4 DOUBLE CRUSH SYNDROME – WITH VIDEO)

A 39-year-old female patient who experienced right L4 radicular pain for 2 months, unresponsive to conservative management. Despite her complaints of leg pain, her neurological examination was found to be intact, with no significant motor or sensory deficits. Radiological investigations, including MRI, revealed lumbar canal stenosis at the L3–4 level and compression of the right-sided L4 nerve root within the foramen of L4–5. This radiological finding strongly correlated with her clinical symptoms of radiculopathy, suggesting that the compression was at the L4 foramen (Figure 6). A minimally invasive approach using unilateral biportal endoscopy with the “extended” contralateral approach was performed. The key steps are highlighted in the Supplementary video clip 1 and Table 1. The patient tolerated the procedure well, with postoperative imaging confirming the successful decompression of the L4 nerve root (Figures 7 and 8). She reported complete resolution in her radicular pain (VAS 0) and made good progress with her recovery.

DISCUSSION

Foraminal stenosis can be challenging to address due to the risk of iatrogenic instability from excessive bone is removal. This drawback is why some surgeons choose to perform a spinal fusion at the index operation to avoid possible revision surgery. With advanced techniques, endoscopic surgery has improved the surgeon’s armamentarium. We can now perform decompressions with less bony resection and reduce the risk of postoperative instability [7].

The endoscopic contralateral approach, in particular, is an effective method of decompressing the spinal nerve roots on the opposite side of the surgeon with minimal manipulation of the thecal sac. The cornerstone of this technique lies in the sublaminar drilling coupled with an optimal working angle that allows the surgeon to effectively decompress the contralateral traversing nerve root and exiting nerve root. To date, this has only been described for pathologies at the same level and only with uniportal surgery [8,9].

By expanding the versatility of this approach, we have shown that it is possible to decompress the nerve root at a second, more caudal level. This gives the benefit of a single position, single approach with less soft tissue dissection, improved operating room efficiency, and still achieving our objective of neural decompression with bony preservation.

There are several pearls to this approach. First, careful planning of the incision is vital and the working port should be positioned lower to allow a sufficient trajectory to decompress the exiting L5 root. Second, the sublaminar drilling of a bony tunnel should be wide enough to introduce the scope and instruments while preserving the thickness of the pars interarticularis. We found a 30° scope with angled instruments extremely useful, especially for the foraminoplasty and discectomy. Lastly, finding the medial and inferior wall of the L5 pedicle can be helpful, as it like a lighthouse to navigate our way around the foramen. From this, we could also find Kambin triangle which allowed us to locate the disc herniation for easy removal.

CONCLUSION

We demonstrate an innovative case of biportal endoscopic “extended” contralateral approach. Using this technique, we can perform a contralateral 2-level decompression through a single biportal approach. This procedure is particularly useful for patients with double crush syndrome, where simultaneous nerve root compression at the lateral recess and exit foramen can be decompressed together. It offers the advantages of improving operating room efficiency while still achieving effective neural decompression without causing iatrogenic instability.

Supplementary Material

Supplementary video clip 1 for this article is available at https://doi.org/10.21182/jmisst.2024.01781.

Supplementary video clip 1.

NOTES

Conflicts of interest

JYLO, is member of the Editorial Board of Journal of Minimally Invasive Spine Surgery & Technique, is the author of this article. However, he played no role whatsoever in the editorial evaluation of this article or the decision to publish it. Except for that, no potential conflict of interest relevant to this article was reported.

Funding/Support

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

Figure 1.

Magnetic resonance imaging showing 2 areas of compression of the right L5 root. L4–5 central canal stenosis in sagittal (A) and axial views (B). Right L5–S1 herniated disc causing foraminal compression (arrow) in the parasagittal (C) and axial views (D).

Figure 2.

Skin incision for the L4–5 “extended” contralateral approach. Compared to the standard ports (red circle), the incisions were shifted more caudal (blue oval circle). The arrows and shaded area in red illustrate the possible working area with this approach.

Figure 3.

Bony resection for extended contralateral decompression. (A) The blue area denotes the L5 laminotomy on the ipsilateral side and base of spinous process. The green area shows the path of the sublaminar drilling to decompress the L5–S1 foramen. (B) Postoperative computed tomography showing left L5 laminotomy (yellow arrow). (C) Preservation of the right L5 pars after sublaminar drilling (yellow star).

Figure 4.

Tracing the L5 nerve root after decompression. (A) The 3 coloured circles represent the corresponding endoscopic views. (B) L4–5 central canal. (C) Lateral recess and axilla. (D) Exiting nerve root decompressed. (E, F) A probe is inserted, and a C arm is used to check its position within the foramen.

Figure 5.

(A–C) Postoperative magnetic resonance imaging showing good decompression of the L4–5 central canal and the L5–S1 foramen (yellow arrow). (D) The skin incisions were closed over a drain.

Figure 6.

Magnetic resonance imaging showing 2 areas of compression of the right L4 root. (A) L3–4 central canal stenosis in sagittal (B) and axial (C) views. Right L4–5 foramina stenosis causing L4 root compression (arrow). (D) Axial view at L4–5.

Figure 7.

Endoscopic decompression using the extended contralateral approach. (A) L3–4 central canal decompression performed to reveal the thecal sac and the lateral recess. (B) Contralateral right L4 root visualized after foraminal decompression.

Figure 8.

(A–C) Postoperative magnetic resonance imaging showing good decompression of the L3–4 central canal and the right L4–5 foramen (orange arrow). (D) Postoperative 3-dimensional scan showing ipsilateral L3 and L4 laminotomy (yellow arrows).

Table 1.

Outline of key steps for the “extended” contralateral approach

1. Docking and exposure of L3–4 interlaminar space (L3 laminotomy)

2. Ipsilateral laminotomy (L3)

3. Contralateral sublaminar laminotomy (L3)

4. Ipsilateral detachment and removal of ligamentum flavum

5. Contralateral detachment and removal of ligamentum flavum

6. Ipsilateral laminotomy of upper portion of caudal lamina (L4)

7. Contralateral sublaminar drilling and foraminoplasty (L4)

8. Decompression of L4 root - from L3–4 lateral recess to L4–5 foramen

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