Single-Incision Posterior Endoscopic Cervical Foraminotomy for 2-Level Cervical Radiculopathy

Florian Wanivenhaus; Christoph Johannes Laux; Sohrab Gollogly; Jin-Sung Kim; Mazda Farshad

doi:10.21182/jmisst.2024.01858

Abstract

This report demonstrates the preoperative workup, surgical planning, and execution for performing 2-level posterior endoscopic foraminotomy. Unilateral radiating arm pain, resulting from degenerative changes in the cervical spine, typically stems from lateral disc herniations or osteophytes within the intervertebral foramen. Posterior endoscopic cervical foraminotomy is a minimally invasive surgical technique to decompress the cervical nerve root without sacrificing a motion segment. A 42-year-old male patient with C6 and C7 radiculopathy experienced insufficient pain relief in response to nonoperative therapy. Radiological imaging demonstrated a neuroforaminal nerve compression at the left side of the C6 and C7 levels. Two-level single-incision posterior cervical endoscopic foraminotomy was performed. In this detailed demonstration of the case, the reader will learn the surgical technique and anatomical considerations to safely perform this cervical endoscopic procedure.

Key Words: Endoscopy, EndoSpine, Cervical radiculopathy, Cervical forminal stenosis, Cervical disc herniation

We are presenting a case of a patient with 2-level cervical radiculopathy treated with posterior endoscopic cervical foraminotomy.

A 42-year-old male patient presented with 1 year of moderate to strong cervical pain and since 3 weeks he experienced left arm pain and numbness in the C6 and C7 distribution. The patient had already undergone nonoperative treatment that included physical therapy, painkillers and an indirect C7 nerve root injection. A temporary pain relieve was noted after the injection. On examination, the patient had no motor weakness. Radiological imaging revealed a segmental degeneration C6–7 und stenotic left sided neural foramen at the level C5–6 and C6–7. That can best be visualized on the parasagittal cuts of the magnetic resonance imaging (MRI) scan.

WRITTEN TRANSCRIPT

0:56 Choice of Surgical Technique

The two main surgical approaches to treat cervical radiculopathy are anterior cervical discectomy and fusion (ACDF) or posterior cervical foraminotomy. ACDF has specific potential problems, which include pseudoarthrosis, approach-related complications like dysphagia, dysphonia, and neck viscera injury, and adjacent segment disease [1-3]. Cervical artificial disc replacement for preserving the motion segment involves sacrificing an intervertebral disc to decompress the nerve root [2]. Open posterior foraminotomy using a midline incision with subperiosteal dissection of the muscles, carries with it a potential significant perioperative morbidity from neck pain and wound issues [1-3]. Therefore, posterior endoscopic cervical foraminotomy was developed and has the potential to decrease wound related complications due to its ability to preserve soft tissue and the continous irrigation [2].

01:52 Patient Positioning

Under general anaesthesia the patient was positioned prone on hip and chest bolsters on the operating room table. The face was positioned on a horse shoe shaped pillow supporting bony prominence. The head attachment was tilted down slightly allowing cervical spine flexion and secured with plaster. A reversed Trendelenburg position was used to elevate the surgical site above the heart to reduce venous bleeding. We did not use intraoperative neuromonitoring. No muscles relaxants were administered after intubation.

02:25 Radiological Localization and Skin Incision

For localization an initial guide wire insertion is not recommended because it may enter the interlaminar space and cause spinal cord injury [1].

A 1-cm longitudinal skin incision was made approximately 1.5-cm lateral from the midline at the midpoint between the C5–6 und C6–7 segment. The superficial fascial planes were sharply dissect with the blade. The paraspinal muscles were bluntly divided with a trocar under lateral fluoroscopic control. The trocar was docked on the laminofacet junction. The lamina to lamina junction can be felt as a distinct step off. The dilators and then the working tube were inserted. Fluoroscopy was used to verify the placement and trajectory of the working sheath. The inferior and dorsal aspect of the facet articulation on the lateral x-ray is coincident with the level of the same disc space (Figure 1). Typically it is easier to confirm the correct level at the cranial segment, in our case C5–6 [4].

03:14 Introduction of the Endoscope

The endoscope is inserted through the sleeve, and the surgical site is under continuous saline irrigation. In this case a 10-mm endoscope with a 5.6-mm working channel was used. The residual soft tissue was ablated using the radiofrequency probe and the “V-point” was clearly exposed under endoscopy.

The “V” point is defined as junction of confluence of the cranical and caudal lamina and facet which has a V shape configuration [5].

03:45 Laminotomy and Partial Facetectomy

Once the V-point was identified the medial aspect of the lateral mass and facet joint was drilled with a 5.5-mm high-speed diamond burr. A Kerrison punch was used to remove additional bone.

The ligamentum flavum is attached to two-thirds of the undersurface of the superior lamina. Inferiorly, it is attached only to the superior edge of the lower lamina [6]. The ligament is thinned out and the epidural space becomes visible.

04:10 Identification of the Nerve Root and Decompression

The nerve root was exposed from its origin at the thecal sac laterally. Observation and identification of the "T" shape of the dural surface vascularity visually confirms the location of the nerve root in the surgical field and is a consistent landmark (Figure 2). The nerve root is transversed dorsally by a foraminal ligament that is elevated using the radiofrequency probe and resected. A potentially important cause of radicular symptoms may be tethering of the nerve root by the foraminal ligament. The shoulder and axilla of the nerve root is explored and is gently retracted in caudal and cranial direction to release the nerve root from peridural adhesions. These adhesions may have developed from persistent inflammation during the period of compression while the nerve root was stenotic. The nerve root was mobile after foraminal bony decompression and resection of the foraminal ligament.

After the C6 nerve root had been decompressed the focus was shifted toward the C6–7 level.

The short interval between adjacent cervical segments allows easy access without making an additional portal. The cervical lordosis also facilitates access to the adjacent level [4]. In this level the same steps for decompression of the C7 nerve root were performed.

Facet joint removal should be less than 50% to prevent segmental instability [7].

A routine discectomy of a contained disc must not performed because the impingent nerve root can be released by removing counterparts of anterior compression like disc protusion or bone spurs [1].

05:17 Management of Intraoperative Bleeding

A concern is significant bleeding when there is a lesion of the venous plexus during exploration and dissection of the epidural space [5].Therefore, control of the bleeding should be a priority in this technique. In our institution we routinely use epinephrine containing saline irrigation and administer intravenous tranexamic acid preoperative.

05:37 Common Complications of PCEF

Common complications of posterior cervical endoscopic foraminotomy may be dural tear, transient root palsy, epidural hematoma, headache and seizures [8,9].

The postoperative course was uneventful, and the patient’s pain improved immediately after surgery. The patient was discharged on the first postoperative day. The patient reported to be pain free and without sensory deficts at the last follow-up 6 months postoperatively.

06:10 Discussion

It was demonstrated that open and endoscopic posterior cervical foraminotomy have a favorable clinical outcomes and sufficient expansion of the midforaminal area. Endoscopic techniques showed a significantly higher inclination angle for undercutting the facet joint and a lower facet resection rate than microsurgical techniques. This may be explained by the off-axis visualization provided by the endoscope [10].

It has been shown that the anatomical correlation of the lateral dural margin overlaps with the V-point at the C5–6 and C6–7 levels, particularly in instances of significant degenerative changes that reduce the anteroposterior diameter of the spinal canal. This results in a bilaterally bulging thecal sac and an increase in the width of the dura. Consequently, the laterally displaced dura edge at the C5–6 and C6–7 levels in elderly patients with advanced degenerative changes should be taken into account. In such cases, a more extensive bone removal is recommended to minimize the risk of potential neural damage [11].

A study involving 108 patients undergoing cervical MRI measured the anatomical distances between the medial borders of the facet joint and the vertebral arteries. The distance from the lateral recess to the vertebral artery decreases from C6–7 (left side, 15.26±2.20 mm) to C5–6 (left side, 12.24±1.86 mm), a variation caused by the artery entering the transverse foramen of C6 from an anterolateral direction. The horizontal distance between the medial margin of the vertebral artery and the medial border of the facet joint on axial MRI at the C5–6 segment on the left side is 5.27±1.58 mm. This indicates that during foraminotomy at the C5–6 level and above, the vertebral artery is usually positioned ventrally, hidden beneath the nerve root [12].

08:09 Conclusion

Uniportal posterior endoscopic cervical foraminotomy is a safe and efficient treatment for cervical radiculopathy that should be considered an alternative to 2-level ACDF or open posterior cervical foaminotomy in selected patients.

NOTES

Conflicts of interest

Mazda Farshad is a consultant for Arthrex, Medacta and Zurimed. Jin-Sung Kim is a consultant for RIWOSpine, GmbH, Germany, Stöckli Medical AG, Switzerland and Elliquence, LLC, USA. Sohrab Gollogly is a consultant for Arthrex. The other authors declare no relevant conflicts of interest related to the video article or its subject matter.

Funding/Support

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

Acknowledgments

We greatly appreciate Mr. Christian Streng’s support with video editing and the EndoSpine Academy for endorsing this work.

Informed Consent

Informed consent from the patient to use the presented radiological and intraoperative video material was obtained.

Figure 1.

The inferior and dorsal aspect of the facet articulation at C5–6 on a sagittal cut of cervical magnetic resonance imaging (MRI) is coincident with the level of the same disc space. (A) Sagittal MRI demonstrating the disc space. (B) Sagittal cut demonstrating the facet joint.

Figure 2.

Identification of the "T" shape of the dural surface vascularity (A) visually confirms the location of the nerve root as a consistent landmark (B).

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