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

Novelties for increased safety in cranio-vertebral surgery: a review

The cranio-vertebral junction (CVJ) was formerly considered a surgical "no man's land" due to its complex anatomical and biomechanical features. Surgical approaches and hardware instrumentation have had to be tailored in order to achieve successful outcomes. Nowadays, thanks to the ongoing development of new technologies and surgical techniques, CVJ surgery has come to be widely performed in many spine centers. Accordingly, there is a drive to explore novel solutions and technological nuances that make CVJ surgery safer, faster, and more precise. Improved outcome in CVJ surgery has been achieved thanks to increased safety allowing for reduction in complication rates. The Authors present the latest technological advancements in CVJ surgery in terms of imaging, biomaterials, navigation, robotics, customized implants, 3D-printed technology, video-assisted approaches and neuromonitoring.

A Pragmatic Neuro-Rehabilitation Approach for Basilar Invagination: A Case Report

Basilar invagination is a rare pathology of the occipital bone, along with prolapsing of the vertebral column. It is a narrowing in the opening of the foramen magnum of the odontoid process. It is a well-known cause of pain and tingling in the upper limbs. However, only a few afflictions requiring physiotherapy rehabilitation in basilar invaginations have been reported. Thus, this study was carried out to investigate a case of basilar invagination. A 51-year-old female visited the neuro-outpatient department. The chief complaints of the patient were restricted overhead activities, restricted neck and shoulder movements, upper limb weakness, and tingling of bilateral upper limbs for the past two months. Clinical examination revealed pain thresholds for the neck and shoulder at nine by ten on activity and five by ten on rest. Manual muscle testing revealed a significant reduction in the strength of muscles around the neck and shoulder at three by five on bilateral upper limbs. The patient was advised to have computed tomography (CT), magnetic resonance imaging (MRI), and a bone density test to confirm the diagnosis of the condition. Investigations revealed a case of basilar invagination. But due to the financial burden, surgery couldn't be opted for; therefore, she opted for physiotherapy rehabilitation. The patient was managed with neuro-physiotherapy rehabilitation exercises like neural tissue stretch, which included nerve gliding and nerve stretching exercises, vestibular rehabilitation exercises, and gaze stabilization exercises. The strengthening of weakened muscles was done using Delorme's technique. Cervical traction, electrotherapy, and moist heat modalities like interferential therapy and hydrocollator packs were given. It also included deep breathing exercises like diaphragmatic breathing and thoracic expansion exercises. The exercise was planned according to the frequency, intensity, time, and type (FITT) principle. Frequency: five days/week; intensity: slow to moderate pace with rest intervals; time: 60 minutes/day; type of exercise: strength training along with other exercises for a total of thirty days. The patient was able to resume her job after receiving physiotherapy rehabilitation, which played a pivotal role in decreasing her symptoms.

Endoscopic endonasal odontoidectomy: a long-term follow-up results for a cohort of 21 patients

BACKGROUND

Endoscopic endonasal odontoidectomy (EEO) has been described as a potential approach for craniovertebral junction (CVJ) disease which could cause anterior bulbomedullary compression and encroaching. Due to the atlantoaxial junction's uniqueness and complex biomechanics, treating CVJ pathologies uncovers the challenge of preventing C1-C2 instability. A large series of patients treated with endonasal odontoidectomy is reported, analyzing the feasibility and necessity of whether or not to perform posterior stabilization. Furthermore, the focus is on the long-term follow-up, especially those whom only underwent partial C1 arch preservation without posterior fixation.

METHODS

This study is a retrospective analysis of patients with ventral spinal cord compression for non-reducible CVJ malformation, consecutively treated with EEO from July 2011 to March 2019. Postoperative dynamic X-ray and CT scans were obtained in each case in order to document CVJ decompression as well as to exclude instability. The anterior atlas-dens interval, posterior atlas-dens interval and C1-C2 total lateral overhang were measured as a morphological criteria to determine upper cervical spine stability.

RESULTS

Twenty-one patients (11:10 F:M) with a mean age of 60.6 years old at the time of surgery (range 34-84 years) encountered the inclusion criteria. For all 21 patients, a successful decompression was achieved at the first surgery. In 11 patients, the partial C1 arch integrity did not require a posterior cervical instrumentation on the bases of postoperative and constant follow-up radiological examination. In 13 cases, an improvement of motor function was recorded at the time of discharge. Only one patient had further motor function improvement at follow-up. Among the patients that did not show any significant motor change at discharge, 4 patients showed an improvement at the last follow-up.

CONCLUSIONS

The outcomes, even in C1 arch preservation without posterior fixation, are promising, and it could be said that the endonasal route potentially represents a valid option to treat lesions above the nasopalatine line.

Trans-oral approach for occipital condyle biopsy: Case report and review of literature

Isolated occipital condyle lesions are commonly treated with empirical radiation, with the sole aim of relieving symptoms. Patients rarely undergo surgical biopsy, considering the morbidity associated with open surgery approaches and the importance of surrounding structures limiting the application of computed tomography (CT) scan or fluoroscopic percutaneous needle biopsies. We describe the case of a 66-year-old woman who was admitted on an emergency basis. Her clinical presentation included unilateral occipital headache and ipsilateral hypoglossal nerve palsy. Imaging revealed findings consistent with an isolated right occipital condyle lesion. In order to pursue a tissue diagnosis, essential to dictate medical management accurately, a minimally invasive biopsy of the occipital condyle through the trans-oral route was performed. Combined fluoroscopy, cone-bean CT and angiography allowed safe access to the lesion.

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.

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.

Minimally Invasive Tubular Approach for Occipital Condylar Biopsy and Resection: Case Report and Review of Literature

BACKGROUND

Patients with isolated occipital condyle lesions concerning for metastases rarely undergo surgical biopsies and are more commonly treated with empirical radiation with or without chemotherapy. This is likely related to the morbidity associated with open condylar approaches and the importance of surrounding structures. We present a minimally invasive technique to approach the occipital condyle using a tubular dilating retractor system.

CASE DESCRIPTION

A 38-year-old woman with medical history of breast cancer presented with a 2-month history of headache localizing to the right occipital area and right tongue deviation. Magnetic resonance imaging revealed a heterogeneously enhancing mass within the right occipital condyle. The patient was brought into the operating room and placed in prone position. A 2-cm paramedian incision was made on the right approximately 2.5 cm off midline at the level of C1. Sequential dilation using a tubular retractor system was performed under fluoroscopic guidance. Once the condylar cortex was identified and entered, the tumor was immediately visualized and resected. Operative time was 65 minutes and estimated blood loss was 5 mL. The patient was discharged to home on postoperative day 1.

CONCLUSIONS

This report, to our knowledge, presents the first case of a minimally invasive tubular retractor system-based approach for biopsy and resection of an occipital condylar metastasis causing occipital condyle syndrome. This approach allows for tissue diagnosis to precisely dictate medical management and minimizes the morbidity associated with traditional open surgical approaches.

Clinical Outcomes of Endoscopic Endonasal Odontoidectomy: A Single-Center Experience

BACKGROUND

Odontoidectomy for basilar invagination and craniovertebral junction pathology traditionally has been performed using a transoral route. However, the endoscopic endonasal approach to the anterior craniovertebral junction may offer safer and more effective access when compared with transoral approaches. The objective of this study is to review the surgical outcomes and complications associated with endoscopic endonasal odontoidectomy.

METHODS

This study is a retrospective chart review of all adult patients who underwent an endoscopic endonasal odontoidectomy at a single tertiary care center between January 2011 and May 2019.

RESULTS

Seventeen patients who underwent endoscopic endonasal odontoidectomy were included. The median age at admission was 67 years (range: 33-84 years) and 65% of the patients were female. One patient (1/17, 6%) had vertebral artery injury, which had to be coiled with no neurologic deficits, and 4 patients (4/17, 24%) had intraoperative CSF leaks with no postoperative leak. Fourteen (14/17, 82%) patients were extubated by postoperative day 1. Three patients (3/17, 18%) developed postoperative sinus infections and required antibiotics. Eight patients (8/17, 47%) developed transient postoperative dysphagia. One patient (1/17, 6%) had postoperative epistaxis and 1 patient (1/17, 6%) had postoperative lower cranial nerve symptoms. The median length of hospital stay was 13 days (range: 2-44 days).

CONCLUSIONS

Although the transoral approach has been the traditional route for anterior decompression of the craniovertebral junction, endoscopic endonasal odontoidectomy is a feasible and well-tolerated procedure associated with satisfactory patient outcomes and low morbidity.

Endoscopic transmastoid posterior petrosal approach for locally aggressive tumors in the petrous part of the temporal bone involving the internal auditory canal, jugular foramen, and hypoglossal canal

OBJECTIVE

The posterior petrosal approach is an established surgical method offering wide access to skull base lesions through mastoid air cells. The authors describe their experience with the endoscopic transmastoid "posterior petrosal" approach (EPPAP) for skull base tumors involving the internal auditory canal (IAC), jugular foramen, and hypoglossal canal.

METHODS

The EPPAP was performed for 7 tumors (3 chordomas, 2 chondrosarcomas, 1 schwannoma, and 1 solitary fibrous tumor). All surgical procedures were performed under endoscopic visualization with mastoidectomy. The compact bone of the mastoid air cells and posterior surface of the petrous bone are carefully removed behind the semicircular canals. When removal of cancellous bone is extended superomedially through the infralabyrinthine space, the surgeon can expose the IAC and petrous portion of the internal carotid artery to reach the petrous apex (infralabyrinthine route). When removal of cancellous bone is extended inferomedially along the sigmoid sinus, the surgeon can safely reach the jugular foramen (transjugular route). Drilling of the inferior surface of petrous bone is extended further inferoposteriorly behind the jugular bulb to approach the hypoglossal canal and parapharyngeal space through the lateral aspect of the occipital condyle (infrajugular route).

RESULTS

Of the 7 tumors, gross-total resection was achieved in 4 (57.1%), subtotal resection (> 95% removal) in 2 (28.6%), and partial resection (90% removal) in 1 (14.2%). Postoperatively, 2 of 3 patients with exudative otitis media showed improvement of hearing deterioration, as did 2 patients with tinnitus. Hypoglossal nerve palsy and swallowing difficulty were improved after surgery in 2 patients and 1 patient, respectively. In 1 patient with severe cranial nerve deficits before surgery, symptoms did not show any improvement.

CONCLUSIONS

The authors present their preliminary experience with EPPAP for skull base tumors in the petrous part of the temporal bone and the lateral part of the occipital condyle involving the cranial nerves and internal carotid arteries. The microscope showed a higher-quality image and illumination in the low-power field. However, the endoscope could offer wider visualization of the surgical field and contribute to minimizing the size of the surgical pathways, necessity of brain retraction, and eventually the invasiveness of surgery. Thus, the EPPAP may be safe and effective for skull base tumors in the petrous region, achieving balance between the radicality and invasiveness of the skull base surgery.

How I do it? Cranial setup for cranial settling

BACKGROUND

Expanded endonasal endoscopic techniques allow us to treat several pathologies related to the odontoid process and craniocervical junction. Cases such as giant basilar invagination represent a surgical challenge.

METHODS

The authors provide technical nuances and describe how to complete an endoscopic endonasal odontoidectomy and release the craniocervical junction with the aim of restoring a correct sagittal balance in cases with giant basilar invagination. The study of cadaveric specimens adds clarifying dissections.

CONCLUSIONS

Endonasal endoscopic odontoidectomy and craniocervical junction joint release allow the treatment of irreducible basilar invagination and restoration of better sagittal balance before posterior cervical occipitocervical fusion.

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.

Transnasal Endoscopic Biopsy Approach to Atlas Tumor with X-ray Assisted and Related Radiographic Measure

OBJECTIVE

To develop an endoscopic transnasal approach to atlas tumors and study its practicability.

METHODS

This article comprises two components: an illustrative case report and observational data on 50 volunteers. As to the case report, a 34 year old man presented with occipital pain for more than 3 months and underwent systematic investigation in Qilu Hospital of Shandong University. CT and MRI scans showed bony destruction in the craniovertebral junction (CVJ) suggestive of tumor. Via an endoscopic transnasal approach to the suspected atlas tumor through the inferior nasal meatus, a Gallini biopsy needle was used to obtain tissue for examination. The procedure was performed endoscopically with double orientation X-ray guidance and coaxial technology after establishing the shortest distance for the biopsy track and range of target tissue and was assisted by manual palpation. As to the observational data, 50 volunteers underwent atlas-related morphometric image measurement using gemstone CT equipment. Biopsy track angles, range for biopsy of the atlas and biopsy track distances were measured by a blinded operator on CT images.

RESULTS

CASE REPORT

pathological examination of the biopsy resulted in diagnosis of a chordoma. There were no complications such as bleeding, infection or spinal cord injury. One month later, the patient underwent tumor resection and reconstruction in other hospital and the diagnosis of chordoma was confirmed by pathological examination of the resected specimen. Observational data: measurements obtained from CT scans of the 50 volunteers were as follows. Biopsy track angles: mean leaning inside angle 3.53° ± 0.39° and mean posterior slope angle 13.05° ± 1.39°. Range for atlas biopsy: transverse diameter 11.84 ± 1.24 mm and longitudinal diameter 9.67 ± 0.90 mm. Biopsy track distances: from atlas to nostril, and to anterior and posterior edges of the inferior turbinate mucosa were 94.52 ± 5.03 mm, 78.21 ± 4.63 mm, and 33.51 ± 3.13 mm, respectively.

CONCLUSIONS

An endoscopic transnasal approach enables biopsy and diagnosis of tumors in the anterior arch of the atlas. Relevant measurements were obtained by assessing CT scans of 50 volunteers to assist operators to determine the effective and safe range for transnasal atlas biopsy.

Endoscopic endonasal approach to the ventral brainstem: anatomical feasibility and surgical limitations

OBJECTIVE Sporadic cases of endonasal intraaxial brainstem surgery have been reported in the recent literature. The authors endeavored to assess the feasibility and limitations of endonasal endoscopic surgery for approaching lesions in the ventral portion of the brainstem. METHODS Five human cadaveric heads were used to assess the anatomy and to record various measurements. Extended transsphenoidal and transclival approaches were performed. After exposing the brainstem, white matter dissection was attempted through this endoscopic window, and additional key measurements were taken. RESULTS The rostral exposure of the brainstem was limited by the sella. The lateral limits of the exposure were the intracavernous carotid arteries at the level of the sellar floor, the intrapetrous carotid arteries at the level of the petrous apex, and the inferior petrosal sinuses toward the basion. Caudal extension necessitated partial resection of the anterior C-1 arch and the odontoid process. The midline pons and medulla were exposed in all specimens. Trigeminal nerves were barely visible without the use of angled endoscopes. Access to the peritrigeminal safe zone for gaining entry into the brainstem is medially limited by the pyramidal tract, with a mean lateral pyramidal distance (LPD) of 4.8 ± 0.8 mm. The mean interpyramidal distance was 3.6 ± 0.5 mm, and it progressively decreased toward the pontomedullary junction. The corticospinal tracts (CSTs) coursed from deep to superficial in a craniocaudal direction. The small caliber of the medulla with very superficial CSTs left no room for a safe ventral dissection. The mean pontobasilar midline index averaged at 0.44 ± 0.1. CONCLUSIONS Endoscopic endonasal approaches are best suited for pontine intraaxial tumors when they are close to the midline and strictly anterior to the CST, or for exophytic lesions. Approaching the medulla is anatomically feasible, but the superficiality of the eloquent tracts and interposed nerves limit the safe entry zones. Pituitary transposition after sellar opening is necessary to access the mesencephalon.

Image-guided transoral approach in severe craniovertebral junction malformations at the golden age of endoscopy: Regarding 2 cases

INTRODUCTION

The image-guided transoral approach (IGTOA) provides a safe exposure to skull base midline lesions and the ventral aspect of the craniovertebral junction (CVJ). The IGTOA has several advantages: the head being placed in the extended position, it decreases the brainstem angulation during surgery; the approach being done through the avascular median pharyngeal raphe, not only lowers the bleeding risk but also provides a direct access to the bony pathology and granulation tissue accessible only via the ventral route. Wide field exposure and maneuverability are necessary to deal with the entire ventral brainstem compression in case of severe CVJ malformation to safely perform partial clivectomy and odontoidectomy.

PRESENTATION OF TWO CASES

We illustrate the cases of two patients, 52-year-old and 42-year-old males, who presented with an impressive craniovertebral junction malformation, confirmed on CT and MRI images. They first underwent surgery by IGTOA, later completed by occipitocervical fixation. For the two patients, outcomes were assessed respectively at 4 and 5 years and showed satisfactory results both clinically and radiologically.

CONCLUSION

In patients with marked ventral compression, the IGTOA provides direct and guided access to the anterior aspect of the CVJ and effective means for odontoidectomy and clivectomy. This approach is more easily maneuverable compared to the endonasal endoscopic approach. The IGTOA approach is quite a complex technique, requiring multidisciplinary skills, but it should primarily be used in difficult situations. We suggest that endonasal endoscopy is over-utilized. We consider that endoscopy should not be routinely performed and kept only for well-selected cases.