The endoscopic endonasal approach to cranio-cervical junction: the complete panel

Analysis of Failed Atlantoaxial Reduction: Causes of Failure and Strategies for Revision

OBJECTIVE

The craniovertebral junction (CVJ) presents intricate anatomical challenges. In severe or irreducible malformations, complications such as reduction loss and fixation failure may occur, necessitating revision surgery. The posterior facet joint distraction and fusion (PFDF) technique, offers a solely posterior approach for revisions. Hence, we delineate varied revision scenarios, proposing surgical strategies and technical details to enhance outcomes and mitigate risks, thereby enriching the neurosurgical community's repertoire.

METHODS

This was a retrospective cohort study, analyzed patient data from Xuanwu Hospital, between 2017 to 2023. All patients had a history of surgical treatment for CVJ malformations, and experienced failure or loss of reduction. The distance from the odontoid process tip to the Chamberlain's line (DCL), the atlantodental interval (ADI), clivus-canal angle, cervicomedullary angle, width of subarachnoid space, CVJ area, and width of syrinx were used for radiographic assessment. Japanese Orthopaedic Association (JOA) scores and SF-12 scores were used for clinical assessment. Independent sample t-tests were employed. A significance level of p < 0.05 indicates statistically significant differences.

RESULTS

We analyzed data from 35 patients. For patients who underwent PFDF, the postoperative DCL, ADI, and clivus-canal angle significantly improved. For all patients, the postoperative cervicomedullary angle, width of subarachnoid space, CVJ area, and width of syrinx all demonstrated significant improvement, indicating the relief of neural compression. All patients showed significant improvement in both symptoms and clinical assessments.

CONCLUSION

Severe atlantoaxial joint locking or ligament contracting are the fundamental cause of reduction and fixation failure. Anterior odontoidectomy is indicated for patients with robust bony fusion of the atlantoaxial joint in an unreduced position. The PFDF technique is safe and effective for patients with incomplete atlantoaxial bony fusion. Preoperative assessment of surgical feasibility and vertebral artery status ensures surgical safety and efficacy.

[Minimally invasive surgery for invaginated CII odontoid process]

Odontoidectomy is indicated for anterior compression of the brainstem by invaginated odontoid process. This procedure can currently be performed via transoral microsurgical and transnasal endoscopic access.

OBJECTIVE

To analyze the results of endoscopic transnasal odontoidectomy.

MATERIAL AND METHODS

We assessed treatment outcomes in 10 patients with anterior compression of the brainstem by invaginated odontoid process. All patients underwent endoscopic transnasal odontoidectomy.

RESULTS

Brainstem decompression was achieved in all cases.

CONCLUSION

Currently, endoscopic transnasal approach is gradually replacing the transoral one in some patients requiring anterior odontoidectomy. Analysis of literature data reflects the development of this technique taking into account various features of surgical treatment including optimization of dimensions of surgical field, attempts to perform C1-sparing surgeries and analysis of sufficient size of trepanation. Nasopalatine and nasoclival lines are used to select optimal access. Nevertheless, the choice of access depends on equipment of the hospital and surgical experience in most cases.

The rhinopharyngeal flap for reconstruction of lower clival and craniovertebral junction defects

OBJECTIVE

The endoscopic endonasal approach (EEA) to the lower clivus and craniovertebral junction (CVJ) has been traditionally performed via resection of the nasopharyngeal soft tissues. Alternatively, an inferiorly based rhinopharyngeal (RP) flap (RPF) can be dissected to help reconstruct the postoperative defect and separate it from the oropharynx. To date, there is no evidence regarding the viability and potential clinical impact of the RPF. The aim of this study was to assess RPF viability and its impact on clinical outcome.

METHODS

A retrospective cohort of 60 patients who underwent EEA to the lower clivus and CVJ was studied. The RPF was used in 30 patients (RPF group), and the nasopharyngeal soft tissues were resected in 30 patients (control group).

RESULTS

Chordoma was the most common surgical indication in both groups (47% in the RPF group vs 63% in the control group, p = 0.313), followed by odontoid pannus (20% in the RPF group vs 10%, p = 0.313). The two groups did not significantly differ in terms of extent of tumor (p = 0.271), intraoperative CSF leak (p = 0.438), and skull base reconstruction techniques other than the RPF (nasoseptal flap, p = 0.301; fascia lata, p = 0.791; inlay graft, p = 0.793; and prophylactic lumbar drain, p = 0.781). Postoperative soft-tissue enhancement covering the lower clivus and CVJ observed on MRI was significantly higher in the RPF group (100% vs 26%, p < 0.001). The RPF group had a significantly lower rate of nasoseptal flap necrosis (3% vs 20%, p = 0.044) and surgical site infection (3% vs 27%, p = 0.026) while having similar rates of postoperative CSF leakage (17% in the RPF group vs 20%, p = 0.739) and meningitis (7% in the RPF group vs 17%, p = 0.424). Oropharyngeal bacterial flora dominated the infections in the control group but not those in the RPF group, suggesting that the RPF acted as a barrier between the nasopharynx and oropharynx.

CONCLUSIONS

The RPF provides viable vascularized tissue coverage to the lower clivus and CVJ. Its use was associated with decreased rates of nasoseptal flap necrosis and local infection, likely due to separation from the oropharynx.

Retro-Odontoid Pseudotumor Formation in the Context of Various Acquired and Congenital Pathologies of the Craniovertebral Junction and Surgical Techniques

Retro-odontoid pseudotumor formation consists of an abnormal growth of granulation tissue typically posterior to the odontoid process, resulting as a manifestation of atlantoaxial instability. This instability can occur as a result of conditions ranging from severe mechanical trauma to metabolic disease or autoimmune conditions such as rheumatoid arthritis. A pseudotumor may impinge on the spinal nerves or even the spinal cord and brainstem, manifesting symptoms from severe neck pain to cervicomedullary compression or myelopathy, and in some cases even sudden death. The objective of this review is to consolidate the findings in published case reports and relevant prior literature reviews regarding the formation of retro-odontoid pseudotumor. We address the pathophysiology involved in acquired and congenital pseudotumor formation, including those associated with rheumatoid arthritis (panni). Additionally, we discuss past and current operative techniques designed to curtail and ultimately regress a retro-odontoid pseudotumor and pannus. Surgical techniques that are addressed include ventral decompression (both transoral and transnasal), dorsal decompression, and indications for posterior instrumentation in pannus formation, particularly in cases that may be sufficiently treated in lieu of an anterior approach. Finally, we will examine the role of external orthoses as both a method of conservative treatment as well as a potential adjunct to the aforementioned surgical procedures.

Focused endoscopic endonasal craniocervical junction approach for resection of retro-odontoid lesions: surgical techniques and nuances

BACKGROUND

Lesions posterior to the odontoid process pose a surgical challenge. Posterolateral approaches to this region are considerably risky for the spinal cord. Transoral approaches are limited in terms of exposure and can also carry morbidity.

METHODS

We describe a focused endoscopic endonasal approach (EEA) for removing an osteochondroma located dorsal to the odontoid process. The surgical pearls and pitfalls using stepwise image-guided EEA cadaveric dissections are highlighted defining the importance of various craniocervical junction (CCJ) lines on imaging.

CONCLUSION

EEA to CCJ can be offered, with lower morbidity than other approaches, even for lesions that extend posterior and caudal to the odontoid process. Radiologic predictors of exposure and intraoperative techniques to enhance endoscopic visualization are discussed.