The selective odontoidectomy: endoscopic endonasal approach to the craniocervical junction

Craniovertebral Junction Instability after Oncological Resection: A Narrative Review

The craniovertebral junction (CVJ) is a complex transition area between the skull and cervical spine. Pathologies such as chordoma, chondrosarcoma and aneurysmal bone cysts may be encountered in this anatomical area and may predispose individuals to joint instability. An adequate clinical and radiological assessment is mandatory to predict any postoperative instability and the need for fixation. There is no common consensus on the need for, timing and setting of craniovertebral fixation techniques after a craniovertebral oncological surgery. The aim of the present review is to summarize the anatomy, biomechanics and pathology of the craniovertebral junction and to describe the available surgical approaches to and considerations of joint instability after craniovertebral tumor resections. Although a one-size-fits-all approach cannot encompass the extremely challenging pathologies encountered in the CVJ area, including the possible mechanical instability that is a consequence of oncological resections, the optimal surgical strategy (anterior vs posterior vs posterolateral) tailored to the patient's needs can be assessed preoperatively in many instances. Preserving the intrinsic and extrinsic ligaments, principally the transverse ligament, and the bony structures, namely the C1 anterior arch and occipital condyle, ensures spinal stability in most of the cases. Conversely, in situations that require the removal of those structures, or in cases where they are disrupted by the tumor, a thorough clinical and radiological assessment is needed to timely detect any instability and to plan a surgical stabilization procedure. We hope that this review will help shed light on the current evidence and pave the way for future studies on this topic.

Transnasal Endoscopic and Transoral Approaches in the Biopsies of Ventral Atlas and Axis Vertebrae: A Comprehensive Retrospective Study for Preprocedural Scheme, Biopsy Procedure, Core Technique Analysis, Diagnostic Yield and Clinical Outcome

OBJECTIVE

This study aims to describe and analyze the transoral and transnasal approaches for pathologies of the ventral atlas and axis vertebrae, which are considered technically challenging regions for diagnostic biopsy.

METHODS

A series of transnasal endoscopic approach (TNA) and transoral approach (TOA) biopsies for the pathologies of the first and second cervical vertebrae were conducted and retrospectively analyzed from July 2014 to May 2021. The depth of the biopsy trajectory was measured on computed tomography images for all nine patients (eight males and one female with an average age of 58.11 ± 11.60 years), as were the coronal, sagittal, and vertical biopsy safe ranges. The characteristics of each lesion, including radiographic features, blood supply, and destruction of anterior or posterior vertebral body edges, were evaluated to guide the biopsy. Four biopsy core techniques (BCTs), including "lesion perforating", "aspiration", "cutting-and-scraping" and "biopsy forceps utilization" were elaborated in this study. The biopsy procedures and periprocedural precautions were demonstrated. Patient demographics, clinical data, lesion characteristics, diagnostic yield, and complications were recorded for each case.

RESULTS

Eight TOA biopsies for the axis vertebral body and one TNA biopsy for the atlas anterior arch were successfully performed and yielded adequate pathologies. All biopsies were organized based on the preprocedural radiographic measurements, which showed that the average length of biopsy trajectory and coronal, sagittal, and vertical safe biopsy ranges were 85.00 ± 5.88, 20.63 ± 4.75, 16.25 ± 1.49, and 24.63 ± 2.26 mm, respectively, and these corresponding data were 95, 36, 9, and 26 mm in the TNA patient. Six osteolytic lesions (66.7%), one osteoblastic lesion (11.1%), and two mixed lesions (22.2%) were observed, among which seven lesions had a rich blood supply. Biopsy forceps and core needles were utilized to obtain samples in six and three patients, respectively. All the TNA and TOA biopsies were performed with cooperative application of multiple BCTs under compound anatomic and stereotactic navigations. Intraprocedural or postprocedural complications occurred in no patients who underwent the biopsy in the follow-up period (1-39 months). No significant differences were found between the preprocedural and postprocedural blood indexes and visual analogue scale scores.

CONCLUSION

With a sophisticated preprocedural arrangement, cooperative application of BCTs, and careful periprocedural precautions, transnasal endoscopic and transoral biopsies are two feasible, efficient, and well-tolerated procedures that achieve satisfactory diagnostic yield, complication rate, and clinical outcome.

Reconsideration of the transoral odontoidectomy in complex craniovertebral junction patients with irreducible anterior compression

Background

Although the single-stage posterior realignment craniovertebral junction (CVJ) surgery could treat most of the basilar invagination (BI) and atlantoaxial dislocation (AAD), there are still some cases with incomplete decompression of the spinal cord, which remains a technique challenging situation.

Methods

Eleven patients were included with remained myelopathic symptoms after posterior correction due to incomplete decompression of the spinal cord. Transoral odontoidectomy assisted by image-guided navigation and intraoperative CT was performed. Clinical assessment and image measurements were performed preoperatively and at the most recent follow-up.

Results

Eleven patients were followed up for an average of 47 months. Symptoms were alleviated in 10 of 11 patients (90.9%). One patient died of an unknown reason 1 week after the transoral approach. The clinical and radiological parameters pre- and postoperatively were reported.

Conclusion

Transoral odontoidectomy as a salvage surgery is safe and effective for properly selected BI and AAD patients after inadequate indirect decompression from posterior distraction and fixation. Image-guided navigation and intraoperative CT can provide precise information and accurate localization during operation, thus enabling complete resection of the odontoid process and decompression of the spinal cord.

Navigation-Guided Measurement of the Inferior Limit Through the Endonasal Route to the Craniovertebral Junction

BACKGROUND

The endoscopic endonasal approach (EEA) has been accepted as an alternative option for diseases at the craniovertebral junction. However, the inferior destination through the endoscopic endonasal approach is anatomically higher than that of the transoral approach. Therefore, preoperative assessment of accessibility is mandatory for appropriate selection of indication. Using a navigation system, we examined the inferior limit through the endonasal route and evaluated the relationships between surrounding anatomicl structures and the lowest point.

METHODS

This study included patients who underwent endoscopic transsphenoidal surgery for intrasellar lesions at our hospital (N = 23). At the start of surgery, the lowest point (target point [TP]) was marked with a straight probe under guidance of the navigation system. We measured 4 parameters on preoperative computed tomography: nasal length, hard palate length, anterior-posterior diameter of the nasopharynx, and nasopalatine angle. Patients were classified into groups depending on whether the TP was at or above (group A) or below (group B) the hard palatine line.

RESULTS

TPs were above the hard palatine line in 15 patients (group A) and below the hard palatine line in 8 patients (group B). No TPs reached the nasopalatine line. Nasal length (P = 0.03) and nasopalatine angle (P = 0.01) were larger in group B than in group A. There were no significant differences in anterior-posterior diameter of the nasopharynx or hard palate length.

CONCLUSIONS

The hard palatine line is a reliable parameter for assessing the inferior limit of the endoscopic endonasal approach. Nostril size affects accessibility with surgical instruments.

Endoscopic Transseptal Approach with Posterior Nasal Spine Removal: A Wide Surgical Corridor to the Craniovertebral Junction and Odontoid: Technical Note and Case Series

BACKGROUND

The transnasal approach to lesions involving the craniovertebral junction represents a technical challenge because of limited inferior exposure. The endoscopic transseptal approach (EtsA) with posterior nasal spine (PNS) removal is described. This technique can create a wide exposure of the craniovertebral junction, thereby increasing the caudal exposure.

METHODS

On patients undergoing anterior craniovertebral junction decompression, we calculated the degree of exposure on the sagittal plan through a paraseptal route, an EtsA without and with PNS removal. The horizontal exposure and working area with the latter approach were also evaluated.

RESULTS

Five patients underwent the transnasal procedure. The age of patients ranged from 34-71 years. All patients harbored basilar impression. The mean postoperative Nurick grade (1, 8) was improved versus the average preoperative grade (3). The average follow-up duration was 16 months. All patients underwent occipitocervical fixation. The mean vertical distances, from the clinoid recess to the inferior most limit with the paraseptal approach, EtsA without and with PNS removal were 38.52, 44.12, and 51.16 mm, respectively. The difference between our approach and a standard paraseptal route was statistically significant (P = 0.041; P< 0.05). The mean horizontal distances were 31.68 mm (mononostril entry) and 35.37 mm (binostril entry). The mean working area was 1795.53 mm².

CONCLUSIONS

Endoscopic endonasal approaches to the craniovertebral junction are increasing, but the downward extension on the anterior cervical spine represents a limit. Therefore, many surgeons prefer transoral or transcervical approaches. The EtsA with PNS removal allows for a more caudal exposure than the standard paraseptal approach, with reduced nasal trauma.

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

We aim to establish a complete summary on the Endoscopic Endonasal Approach (EEA) to Cranio Cervical Junction (CCJ): evolution since first description, criteria to predict the feasibility and limitations, anatomical landmarks, indications and biomechanical evaluation after performing the approach. A comprehensive literature search to identify all available literature published between March 2002 and June 2015, the articles were divided into four categories according to their main purpose: 1- surgical technique, 2- anatomical landmarks and limitations, 3- literature reviews to identify main indications, 4- biomechanical studies. Thereafter, we demonstrate the approach step-by-step, using 1 fresh and 3 silicon injected embalmed cadaveric specimen heads. 61 articles and one poster were identified. The approach was first described on cadaveric study in 2002, and firstly used to perform odontoidectomy in 2005. The main indication is odontoid rheumatoid pannus and basilar invagination. The nasopalatine line (NPL), the superior nostril-hard palate Line (SN-HP), the naso-axial line (NAxL), the rhinopalatine Line (RPL) and other methods were described to predict the anatomical feasibility of the approach. The craniocervical fusion is potentially unnecessary after removal of < 75% of one occipital condyle. A recent cadaveric study stated the possibility of C1-C2 fusion via EEA. This paper reviews all available clinical and anatomical studies on the EEA to CCJ. The approach marked a significant evolution since its first description in 2002. Because of its lesser complications compared to the transoral approach, the EEA became when feasible, the approach of choice to the ventral CCJ.

Endonasal Endoscopic Odontoidectomy in Ventral Diseases of the Craniocervical Junction: Results of a Multicenter Experience

BACKGROUND

Over the past decades, supported by preliminary anatomic and clinical studies exploring its feasibility and safety, experience has increased of the use of the endoscopic endonasal approach (EEA) to ventral diseases at the craniocervical junction (CCJ).

METHODS

A multicenter study was carried out over a 4-year period of 14 patients managed by EEA odontoidectomy for CCJ diseases causing irreducible atlantoaxial dislocation. The surgical setup included an IGS system based on computed tomography and magnetic resonance images fusion, and 0° and 30° angled endoscopes with dedicated endoscopic tools.

RESULTS

Nine men and 5 women, with a mean age of 60.7 years, were included. The mean follow-up was 28.5 months; 9 patients had basilar impression, whereas 5 had a degenerative pannus. The quality of anterior decompression was excellent in all cases; nonetheless, a posterior stabilization was deemed necessary in 13 patients, and no external orthosis was used during the postoperative course. No tracheostomy or gastrostomy was required after surgery; no deaths, no new neurologic deficits/complications, and no postoperative cerebrospinal fluid leak were recorded. At follow-up, the neurologic status assessed with Frankel grade did not deteriorate in any of the patients but improved in 13 of them; and no new listhesis was shown on neuroradiologic follow-up.

CONCLUSIONS

The results show that EEA provides a direct surgical corridor to the CCJ, allowing an adequate decompression as with the more invasive transoral route. Morbidity is less than with a transoral approach, resulting in higher patient comfort and faster recovery.

Endoscopic Endonasal Approach to the Odontoid Pathologies

BACKGROUND

Surgical anterior decompression represents the treatment of choice for symptomatic irreducible ventral craniovertebral junction (CVJ) compression. With the refinement of the endoscopic techniques, the endonasal route has been proposed as alternative to the classic transoral approach to CVJ. Some reports assess the effectiveness and safety of endoscopic endonasal approaches to CVJ pathologies.

MATERIALS AND METHODS

From July 2011 to February 2014, 12 patients with symptomatic nonreducible ventral spinal cord compression underwent purely 3-dimensional endoscopic endonasal odontoidectomy in our department. The surgical technique is described.

RESULTS

A good brainstem-medullary decompression was achieved in all patients. In 10 of 12 patients the endotracheal tube was removed just after the procedure with good recovery of the respiratory function. We report no cases of velopharyngeal insufficiency. In 5 of 12 patients the preservation of C1 anterior was achieved, without the need for posterior cervical fixation.

DISCUSSION AND CONCLUSIONS

Endoscopic endonasal odontoidectomy has proven to be safe and effective in selected patients. Soft and hard palate preservation dramatically reduces the risk of postoperative velopharyngeal insufficiency. Moreover, the endonasal endoscopic approach provides a direct access to the dens. Three-dimensional high-definition endoscope, laser, and ultrasound bony curettes revealed to be useful tools for this approach that, however, remains a demanding one.

The rhinopalatine line as a reliable predictor of the inferior extent of endonasal odontoidectomies

OBJECT

The endoscopic endonasal approach (EEA) provides a minimally invasive corridor through which the cervicomedullary junction can be decompressed with reduced morbidity rates compared to those with the classic transoral approaches. The limit of the EEA is its inferior extent, and preoperative estimation of its reach is vital for determining its suitability. The aim of this study was to evaluate the actual inferior limit of the EEA in a surgical series of patients and develop an accurate and reliable predictor that can be used in planning endonasal odontoidectomies.

METHODS

The actual inferior extent of surgery was determined in a series of 6 patients with adequate preoperative and postoperative imaging who underwent endoscopie endonasal odontoidectomy. The medians of the differences between several previously described predictive lines, namely the nasopalatine line (NPL) and nasoaxial line (NAxL), were compared with the actual surgical limit and the hard-palate line by using nonparametric statistics. A novel line, called the rhinopalatine line (RPL), was established and corresponded best with the actual limit of the surgery.

RESULTS

There were 4 adult and 2 pediatric patients included in this study. The NPL overestimated the inferior extent of the surgery by an average (± SD) of 21.9 ± 8.1 mm (range 14.7-32.5 mm). The NAxL and RPL overestimated the inferior limit of surgery by averages of 6.9 ± 3.8 mm (range 3.7-13.3 mm) and 1.7 ± 3.7 mm (range -2.8 to 8.3 mm), respectively. The medians of the differences between the NPL and NAxL and the actual surgery were statistically different (both p = 0.0313). In contrast, there was no statistically significant difference between the RPL and the inferior limit of surgery (p = 0.4375).

CONCLUSIONS

The RPL predicted the inferior limit of the EEA to the craniovertebral junction more accurately than previously described lines. The use of the RPL may help surgeons in choosing suitable candidates for the EEA and in selecting those for whom surgery through the oropharynx or the facial bones is the better approach.

Endoscopic endonasal transclival transodontoid approach for ventral decompression of the craniovertebral junction: operative technique and nuances

The transoral approach is considered the gold-standard surgical route for performing anterior odontoidectomy and ventral decompression of the craniovertebral junction for pathological conditions that result in symptomatic cervicomedullary compression, including basilar invagination, rheumatoid pannus, platybasia with retroflexed odontoid processes, and neoplasms. Extended modifications to increase the operative corridor and exposure include the transmaxillary, extended "open-door" maxillotomy, transpalatal, and transmandibular approaches. With the advent of extended endoscopic endonasal skull base techniques, there has been increased interest in the last decade in the endoscopic endonasal transclival transodontoid approach to the craniovertebral junction. The endonasal route represents an attractive minimally invasive surgical alternative, especially in cases of irreducible basilar invagination in which the pathology is situated well above the palatine line. Angled endoscopes and instrumentation can also be used for lower-lying pathology. By avoiding the oral cavity and subsequently using a transoral retractor, the endonasal route has the advantages of avoiding complications related to tongue swelling, tracheal swelling, prolonged intubation, velopharyngeal insufficiency, dysphagia, and dysphonia. Postoperative recovery is quicker, and hospital stays are shorter. In this report, the authors describe and illustrate their method of purely endoscopic endonasal transclival odonotoidectomy for anterior decompression of the craniovertebral junction and describe various operative pearls and nuances of the technique for avoiding complications.

Endoscopic Endonasal Approaches to the Craniovertebral Junction: A Systematic Review of the Literature

Background We reviewed the current literature pertaining to extended endoscopic endonasal approaches to the craniovertebral junction. Methods A systematic literature review was utilized to identify published surgical cases of endoscopic endonasal approaches to the craniovertebral junction. Full-text manuscripts were examined for various measures of surgical indications, patient characteristics, operative technique, and surgical outcomes. Results We identified 71 cases involving endoscopic endonasal approaches for surgical management of a variety of pathologies located within the craniovertebral junction. Patient ages ranged from 3 to 87 years, with 40 females and 31 males. Five patients required tracheostomy, two were reintubated, and all others experienced an average intubation duration of 0.54 days following surgery. Fifty-eight patients (81.7%) underwent an additional posterior decompression or fusion either before or after the endonasal procedure. A complete resection of the pathologic lesion was reported in 57 cases (83.8%), another five were successful biopsies, and four resulted in partial resection. The follow-up time ranged from 0.5 to 57 months. Conclusion Although the transoral approach has been the standard for anterior surgical management for the past several decades, our systematic review illustrates that the extended endoscopic endonasal approach is a safe and effective alternative for most pathologies affecting the craniovertebral junction.