Full-endoscopic Uniportal Odontoidectomy and Decompression of the Anterior Cervicomedullary Junction Using the Retropharyngeal Approach

Full Endoscopic Spine Surgery with Image-Guided Navigation System as "Hybrid Endoscopic Spine Surgery": A Narrative Review

Endoscopic surgery is adopted as a minimally invasive technique in several surgical fields. Endoscopic spine surgery (ESS) was performed initially for lumbar discectomy but is currently widely utilized for various pathologies. Similar to other endoscopic techniques, ESS has a steep learning curve that has recently been a topic of discussion. Image-guided navigation systems have been developed for spine surgery. Intraoperative computed tomography enables the use of an image-guided navigation system in ESS, which is a suitable approach for managing complex lesions. Full-ESS is currently being adopted for certain cervical pathologies, and the incorporation of an image-guided navigation system will soon enable surgery for other cervical pathologies.

Transcervical, retropharyngeal odontoidectomy - Anatomical considerations

Context

Anterior craniocervical junction lesions have always been a challenge for neurosurgeons. Presenting with lower cranial nerve dysfunction and symptoms of brainstem compression, decompression is often required. While posterior approaches offer indirect ventral brainstem decompression, direct decompression via odontoidectomy is necessary when they fail. The transoral and endoscopic endonasal approaches have been explored but come with their own limitations and risks. A novel retropharyngeal approach to the cervical spine has shown promising results with reduced complications.

Aims

This study aims to explore the feasibility and potential advantages of the anterior retropharyngeal approach for accessing the odontoid process.

Methods and Surgical Technique

To investigate the anatomical aspects of the anterior retropharyngeal approach, a paramedian skin incision was performed below the submandibular gland on two cadaveric specimens. The subcutaneous tissue followed by the platysma is dissected, and the superficial fascial layer is opened. The plane between the vascular sheath laterally and the pharyngeal structures medially is entered below the branching point of the facial vein and internal jugular vein. After reaching the prevertebral plane, further dissection cranially is done in a blunt fashion below the superior pharyngeal nerve and artery. Various anatomical aspects were highlighted during this approach.

Results

The anterior, submandibular retropharyngeal approach to the cervical spine was performed successfully on two cadavers highlighting relevant anatomical structures, including the carotid artery and the glossopharyngeal, hypoglossal, and vagus nerves. This approach offered wide exposure, avoidance of oropharyngeal contamination, and potential benefit in repairing cerebrospinal fluid fistulas.

Conclusions

For accessing the craniocervical junction, the anterior retropharyngeal approach is a viable technique that offers many advantages. However, when employing this approach, surgeons must have adequate anatomical knowledge and technical proficiency to ensure better outcomes. Further studies are needed to enhance our anatomical variations understanding and reduce intraoperative risks.

Full-endoscopic uniportal retropharyngeal odontoidectomy: A preliminary case report

Summary of background data

Odontoidectomy aims to decompress the medulla oblongata and is usually performed through the classical transoral approach, which affects oropharynx and accompanied with high rate of complications comprising swallowing and respiratory tract. We have developed a minimal invasive method via a standard cervical anterior approach: full-endoscopic trans-cervical odontoidectomy, which provides an alternative access for the resection of odontoid process and medulla oblongata decompression without traversing potentially contaminated cavities.

Methods

From 2018 to 2020, three patients with either odontoid process lesion or basilar invagination underwent full-endoscopic uniportal trans-cervical odontoidectomy with/without combining the posterior instrumentation. With fluoroscopic guidance, a uniportal endoscope sleeve was placed inside of the odontoid process; then odontoid process was gradually resected from the inside to outside under endoscopic monitoring. Postoperative images and clinical data were collected during post-op follow-up.

Result

Patients were soon extubated after surgery when patients wake up from general anesthesia. There were no severely perioperative complications, especially dysphagia and airway obstruction, and the symptoms and neurological function was improved immediately after surgery. The final pathology of one patient with odontoid osteolytic lesion was confirmed as plasmacytoma. The postoperative CT scans proved that the range of odontoid process resection was consistent with the preoperative expectation.

Conclusion

In summary, our proposed endoscopic trans-cervical odontoidectomy provides a valid choice for non-oral approach, which would reduce postoperative approach related complications and accelerate postoperative recovery.

The Submandibular Approach: A Descriptive Perspective of the Retropharingeal Corridor to the Craniocervical Junction (Microscopic- vs. Endoscopic-Assisted Dissections)

The craniocervical junction refers to an area from the line separating the middle and lower third of the clivus to the base of the dens (anteriorly) and from the posterior edge of the occipital foramen to the spinous process of C2 (posteriorly). Here, the clival region is a challenging surgical target surrounded by a complex neurovascular architecture. Historically, mainly the complex, and high-risk, transmucosal approaches have been the corridors of choice when targeting this region. Nevertheless, the inherent broad anatomic and pathological variants have shown the need for more-malleable and wider approaches. Thus, MacAfee's established retropharyngeal approach has been simplified in parallel to the application of endoscopic surgery, therefore providing access to the clival region through a low-risk retropharyngeal space when compared to homologous anterior transmucosal approaches. The following review analyzes the literature that has specifically described the craniocervical junction after reaching the clivus (or at least after odontoidectomy) through the retropharyngeal corridor, from the perspective of the open approach or the endoscopic submandibular approach.

The Impact of C1 Anterior Arch Preservation on Spine Stability After Odontoidectomy: Systematic Review and Meta-Analysis

BACKGROUND

Odontoidectomy for symptomatic irreducible ventral brainstem compression at the craniovertebral junction may result in spine instability requiring subsequent instrumentation. There is no consensus on the importance of C1 anterior arch preservation in prevention of iatrogenic instability. We conducted a systematic review of the impact of C1 anterior arch preservation on postodontoidectomy spine stability.

METHODS

PubMed, Embase, Scopus, Web of Science, and Cochrane were searched following the PRISMA guidelines to include studies of patients undergoing odontoidectomy. Random-effect model meta-analyses were performed to compare spine stability between C1 anterior arch preservation versus removal and posttreatment outcomes between transoral approaches (TOAs) versus endoscopic endonasal approaches (EEAs).

RESULTS

We included 27 studies comprising 462 patients. The most common lesions were basilar invagination (73.3%) and degenerative arthritis (12.6%). Symptoms included myelopathy (72%) and neck pain (43.9%). Odontoidectomy was performed through TOA (56.1%) and EEA corridors (34.4%). The C1 anterior arch was preserved in 16.7% of cases. Postodontoidectomy stabilization was performed in 83.3% patients. Median follow-up was 27 months (range, 0.1-145). Rates of spine instability were significantly lower (P = 0.004) when the C1 anterior arch was preserved. Postoperative clinical improvement and pooled complications were reported in 78.8% and 12.6% of patients, respectively, with no significant differences between TOA and EEA (P = 0.892; P = 0.346). Patients undergoing EEA had significantly higher rates of intraoperative cerebrospinal fluid leaks (P = 0.002).

CONCLUSIONS

Odontoidectomy is safe and effective for treating craniovertebral junction lesions. Preservation of the C1 anterior arch seems to improve maintenance of spine stability. TOA and EEA show comparable outcomes and complication rates.

Percutaneous Full-Endoscopic C2 Ganglionectomy for the Treatment of Intractable Occipital Neuralgia: Technical Note

BACKGROUND

The C-2 dorsal root ganglionectomy procedure can provide effective treatment for intractable occipital neuralgia (ON). However, the traditional microsurgery of C2 ganglionectomy needs a wide incision and significant paraspinous muscle dissection for adequate visualization. The indications of endoscopic spine surgery are ever expanding, with the development of endoscopic armamentaria and technological innovations.

OBJECTIVE

To validate the feasibility of the approach and describe several operative nuances based on the authors' experience. In this paper, the authors describe a patient with intractable ON who was successfully treated with a percutaneous full-endoscopic C2 ganglionectomy.

METHODS

We describe the case of an 83-yr-old female with a 2-yr history of left ON who did not respond to a series of treatments, including physical therapy, drug therapy, injection therapy, and radiofrequency therapy. After careful examination, we performed a percutaneous, full-endoscopic left C2 ganglionectomy.

RESULTS

The patient was successfully treated with a percutaneous full-endoscopic ganglionectomy. Afterwards, her intractable and constant pain was relieved. There was no cerebrospinal fluid leakage, incision infection, neck deformity, or other complications.

CONCLUSION

C2 ganglionectomy can be accomplished successfully using a full-endoscopic uniportal surgical technique under continuous irrigation, which has the advantages of excellent illumination and visualization, reduced surgery-related trauma, and reduced bleeding.

Full-Endoscopic Transcervical Ventral Decompression for Pathologies of Craniovertebral Junction: Case Series

Odontoidectomy is very effective for the decompression of the ventral craniovertebral junction (CVJ). Various approaches are available for the direct ventral decompression of the CVJ. Because there are many disadvantages of open transoral approach, endoscopic odontoidectomy was developed. There are 3 approaches in endoscopic odontoidectomy. We report transcervical retropharyngeal endoscopic approach for the ventral CVJ in this paper. Three patients with different pathologies received operations using this approach. The decompression was enough and surgical invasion was less in all patients. Each endoscopic approach has some advantages and different working regions due to their approach trajectories, but transcervical retropharyngeal approach is very familiar for our neurospinal surgeons and has a relatively large working area. This approach might have the chance to take the place of open transoral approach for endoscopic spinal surgeons.