Radiographic and anatomic basis of endoscopic anterior craniocervical decompression: a comparison of endonasal, transoral, and transcervical approaches

Endoscopy-assisted high cervical anterolateral retropharyngeal approach to clivus: a cadaveric study

Introduction

The surgical management of pathologies involving the clivus and craniocervical junction has always been considered a complex procedure because of the deeply located surgical targets and the surrounding complex neural and vascular anatomical structures. The most commonly used approaches to reach this area are the transnasal, transoral, and transcervical approaches.

Material and Methods

This approach was performed unilaterally on five cadaver heads and bilaterally on one cadaver head.

Results

We described a modified endoscope-assisted high cervical anterolateral retropharyngeal approach in which each stage of the procedure was demonstrated on human cadavers in a step-by-step manner using endoscopic camera views. This approach was broken down into nine steps. The neurovascular structures encountered at each step and their relationships with each other are demonstrated.

Discussion

The advantages and disadvantages of our modified approach were compared to the conventional transcervical, transoral, and endoscopic endonasal approaches.

Lesson learned in endoscopic endonasal dens resection for C1-C2 spinal cord decompression

PURPOSE

Endoscopic endonasal approach (EEA) is the safest and most effective technique for odontoidectomy. Nevertheless, this kind of approach is yet not largely widespread. The aim of this study is to share with the scientific community some tips and tricks with our ten-year-old learned experience in endoscopic endonasal odontoidectomy (EEO), which remains a challenging surgical approach.

MATERIAL AND METHODS

Our case series consists of twenty-one (10 males, 11 females; age range of 34-84 years) retrospectively analyzed patients with ventral spinal cord compression for non-reducible CVJ malformation, treated with EEA from July 2011 to March 2019.

RESULTS

The results have recently been reported in a previous paper. The only intraoperative complication observed was intraoperative cerebrospinal fluid (CSF) leak (9.5%), without any sign of post-operative CSF leak.

CONCLUSIONS

Considering our experience, EEO represents a valid and safe technique to decompress neural cervical structures. Despite its technical complexity, mainly due to the use of endoscope and the challenging surgical area, with this study we encourage the use of EEO displaying our experience-based surgical tips and tricks.

Gamma Knife radiosurgery for meningiomas of the confluence of the falx and tentorium

PURPOSE

Meningiomas arising from the confluence of the falx and tentorium (CFT) are a rare and challenging subset of meningiomas. Gamma Knife radiosurgery (GKRS) is well-established as a safe and effective management strategy for intracranial meningiomas, but its role in treating CFT meningiomas is not well-described. This paper reports the largest series focused exclusively on the outcomes of GKRS for CFT meningiomas.

METHODS

We retrospectively identified 20 CFT meningiomas out of 2031 meningioma patients who underwent GKRS at our institution between 1987 and 2021. Tumor control, overall survival (OS), and complications were recorded and analyzed. The median tumor margin dose was 13 Gy at the 50% isodose line. The median tumor volume treated was 4.4 cc (IQR 3.5-7.7). The median patient age was 58 years (range 33-83), the median MRI surveillance duration was 59 months (IQR 34-92), and the median overall follow-up duration was 92 months (IQR 42-201).

RESULTS

The local tumor control rate (PFS) at 5 and 10-years were 100% (N=10) and 83% (N=4), respectively. Eight patients had stable tumor volumes and 11 patients had regression. One patient with a twice-operated tumor had delayed progression at 7.5 years and was retreated with GKRS. No patient had adverse radiation effects during the period of MRI surveillance. The 5 and 10-year OS were 100% (N=13) and 100% (N=7), respectively.

CONCLUSIONS

GKRS is a valuable therapeutic strategy for patients with newly diagnosed CFT meningiomas or progressive residual tumors after surgical resection.

Endoscopic Endonasal Transodontoid Treatment of a Ruptured Anterior Spinal Artery Aneurysm

Isolated spinal artery aneurysms are a rare cause of intracranial subarachnoid hemorrhage (SAH). A 49-year-old female presented with severe headache. Initial imaging showed SAH and intraventricular hemorrhage (IVH), but no clear source of bleeding was identified. One week into being observed in the intensive care unit, she reported another severe headache. Computed tomography head showed more SAH and IVH. A second angiogram revealed a ruptured small anterior spinal artery (ASA) aneurysm at the craniocervical junction. She underwent a C1–2 fusion followed by an endoscopic endonasal transodontoid approach and wrapping of the ASA aneurysm. At 2 years' follow-up, there was no sign of aneurysm growth or rerupture. This is the first reported case of an endoscopic endonasal transodontoid approach to an aneurysm.

Endoscopy-assisted anterior cervical debridement combined with posterior fixation and fusion for the treatment of upper cervical spine tuberculosis: a retrospective feasibility study

Background

This retrospective study aimed to determine the feasibility and efficacy of endoscopy-assisted anterior cervical debridement combined with posterior fixation and fusion in patients with upper cervical spine tuberculosis.

Methods

Between June 2008 and January 2016, 17 patients (10 men and 7 women) with upper cervical spine tuberculosis underwent endoscopy-assisted anterior cervical debridement combined with posterior fixation and fusion. Anti-tuberculosis treatment was administered for 2–4 weeks preoperatively and 12–18 months postoperatively. The clinical and radiographic data of the patients were analyzed.

Results

The operation was successfully completed in all patients. Neck pain and stiffness were relieved after the surgery in all patients. The mean operation time was 210.0 ± 21.2 min, and the mean intraoperative blood loss was 364.7 ± 49.6 mL. The mean follow-up duration was 68.1 ± 6.7 months. The erythrocyte sedimentation rate returned to normal by 3 months postoperatively. Visual analog scale scores for neck pain were significantly lower postoperatively than preoperatively. All patients had significant postoperative neurological improvement. Patient-reported outcomes, as measured using the Kirkaldy-Willis criteria, were as follows: excellent, 12 patients; good, 4 patients; fair, 1 patient; and poor, 0 patients. Bone fusion was achieved at 10.9 ± 1.9 months after the surgery; no cases of instrument loosening or fracture occurred.

Conclusion

Endoscopy-assisted anterior cervical debridement combined with posterior fixation and fusion is a feasible and effective surgical method for the treatment of upper cervical spine tuberculosis. It can be used to restore upper cervical spine stability and facilitate spinal healing.

Management of non-vestibular schwannomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section Part II: Trigeminal and facial nerve schwannomas (CN V, VII)

BACKGROUND

Non-vestibular schwannomas are relatively rare, with trigeminal and jugular foramen schwannomas being the most common. This is a heterogenous group which requires detailed investigation and careful consideration to management strategy. The optimal management for these tumours remains unclear and there are several controversies. The aim of this paper is to provide insight into the main principles defining management and surgical strategy, in order to formulate a series of recommendations.

METHODS

A task force was created by the EANS skull base section committee along with its members and other renowned experts in the field to generate recommendations for the surgical management of these tumours on a European perspective. To achieve this, the task force performed an extensive systematic review in this field and had discussions within the group. This article is the second of a three-part series describing non-vestibular schwannomas (V, VII).

RESULTS

A summary of literature evidence was proposed after discussion within the EANS skull base section. The constituted task force dealt with the practice patterns that exist with respect to pre-operative radiological investigations, ophthalmological assessments, optimal surgical and radiotherapy strategies, and follow-up management.

CONCLUSION

This article represents the consensually derived opinion of the task force with respect to the treatment of trigeminal and facial schwannoma. The aim of treatment is maximal safe resection with preservation of function. Careful thought is required to select the appropriate surgical approach. Most middle fossa trigeminal schwannoma tumours can be safely accessed by a subtemporal extradural middle fossa approach. The treatment of facial nerve schwannoma remains controversial.

Surgical Approaches to Tumors of the Occipito-Cervical, Subaxial Cervical, and Cervicothoracic Spine: An Algorithm for Standard versus Extended Anterior Cervical Access

OBJECTIVE

To propose a surgical approach algorithm for the tumors of the cervicothoracic spine.

METHODS

All patients operated for vertebral column tumors involving the occipito-cervicothoracic spine were reviewed. Oncologic characteristics and surgical approach were gathered. Approach was classified by the use of staging and trajectory (posterior, transnasal, transoral, transmandibular, transcervical, transsternal). Angle of attack was defined for the occipitocervical junction tumor as the angle inscribed by the inferior mandibular plane and line connecting the superior tumor pole and mandibular angle. For lesions extending below the thoracic inlet, angle of attack was that inscribed by the plane of the thoracic inlet and the line connecting the jugular notch and inferior tumor pole.

RESULTS

In total, 115 patients were included (mean age 56.7 years, 64 [56%] male, average size 26.5 cm³, 39 [34%] primary tumors). Sixty-nine (60%) of patients had single-stage procedures (57 [49.6%] posterior-only, 12 [10.4%] anterior-only), 35 (30.4%) had 2-stage procedures, and 11 (9.6%) had 3- or 4-stage approaches. Lesions requiring a combined transmandibular-transcervical approach all involved the C2 and C3 levels and had a significantly steeper angle of attack (42.5 ± 9.5 vs. 6.1 ± 13.3°; P = 0.01) and greater superior tumor extent above the inferior plane of the mandible (3.69 ± 2.18 vs. 0.33 ± 0.78; P = 0.002). Lateral tumor extent, tumor size, nor inferior angle of attack differed significantly between approach groups.

CONCLUSIONS

Here, we present a preliminary decision-making algorithm for the management of vertebral column tumors of the cervicothoracic spine. Based on this single-center experience, we suggest which patients, assessed via a combination of tumor histology and regional anatomy, may benefit from extended anterior surgical access.

Anterior cervical osteophytes causing dysphagia: Choice of the approach and surgical problems

Background

Anterior cervical osteophytes (ACOs) may rarely cause dysphagia, dysphonia, and dyspnea. Symptomatic ACOs are most commonly located between C3 and C7, whereas those at higher cervical (C1-C2) levels are rarer. We report a case series of 4 patients and discuss the best surgical approach according to the ostheophyte location and size, mainly for those located at C1-C2, and the related surgical problems.

Materials and Methods

Four patients (two males and two females) aged from 57 to 72 years were operated on for ACOs, causing variable dysphagia (and dyspnea with respiratory arrest in one). Three patients with osteophytes between C3 and C5 were approached through antero-lateral cervical approach, and one with a large osteophyte between C1 and C3-C4 level underwent a two-stage transcervical and transoral approach. All had significant postoperative improvement of dysphagia.

Results

The patient operated on though the transoral approach experienced postoperative flogosis of the prevertebral tissues and occipital muscles and thrombosis of the right jugular vein and transverse-sigmoid sinuses (Lemierre syndrome).

Conclusion

The transoral approach is the best surgical route to resect C1 and C2 ACOs, whereas the endoscopic endonasal approach is not indicated. The anterior transcervical approach is easier to resect osteophytes at C3, as well as those located below C3. A combined transoral and anterior cervical approach may be necessary for multilevel osteophytes.

[Anatomy of anterior craniovertebral junction in endoscopic transnasal approach]

Modern achievements in endoscopic technologies ensure extending the indications for endoscopic transnasal approach in skull base surgery. Knowledge on topographic anatomy of craniovertebral junction is a prerequisite for surgical interventions in this area. Transnasal endoscopic surgery of craniovertebral junction is a relatively new field. Therefore, this manuscript and similar anatomical studies are extremely important for neurosurgeons.

Endoscopic endonasal approaches to the craniovertebral junction: The Otolaryngologist's perspective

Objective

To review indications and techniques for the endoscopic endonasal approach to the craniovertebral junction (CVJ), analyze postoperative outcomes, and discuss important technical considerations.

Methods

A retrospective analysis was performed on all patients undergoing endonasal endoscopic approaches to the CVJ from May 2007 to June 2017. Demographic information, presenting symptoms, imaging results, treatment course, postoperative functional status, and follow-up were recorded.

Results

There was a total of 30 patients in this series, with a mean follow-up of 11.7 months. The average age was 33.6 years (range, 5–75 years), with 18 females and 12 males. The majority of patients (n = 22, 73.3%) had Chiari malformation type 1 with basilar invagination and symptomatic cervicomedullary compression as the indication for surgery. Intraoperative cerebrospinal fluid leak (CSF) was noted in 3 cases of odontoid resection and a single case of skull base resection. There were no postoperative CSF leaks. Overall, 81% of patients resumed regular diet by post-operative day 2 (range, 0–8 days). Severe postoperative dysphagia occurred in two cases with one requiring gastrostomy tube placement and another utilizing total parenteral nutrition for support prior to eventual gastrostomy. On average, patients were extubated by postoperative day 0.93 (range 0–3 days), with 85% extubated by postoperative day 1. A tracheotomy was required in one patient.

Conclusion

The endonasal endoscopic approach is a valuable technique for access to the CVJ with minimal disruption of respiratory and alimentary function.

The full-endoscopic uniportal technique for decompression of the anterior craniocervical junction using the retropharyngeal approach: an anatomical feasibility study in human cadavers and review of the literature

Objective

Acute or progressive myelopathy may necessitate direct anterior decompression of the craniocervical junction and odontoidectomy. Different techniques with individual advantages and disadvantages can be used. In addition to the gold standard-the transoral approach-there is also increasing experience with the endoscopic transnasal technique. Other alternative methods are also being developed to reduce technical and perioperative problems. The aim of this anatomical study was to investigate the feasibility of the full-endoscopic uniportal technique with a retropharyngeal approach for decompression of the craniocervical junction, taking into consideration the specific advantages and disadvantages compared with conventional methods and the currently available data in the literature.

Methods

Five fresh adult cadavers were operated on. The endoscope used has a shaft cross-section of 6.9 × 5.9 mm and a 25° viewing angle. It contains an eccentric intraendoscopic working channel with a diameter of 4.1 mm. An anterior retropharyngeal approach was used. The anatomical structures of the anterior craniocervical junction were dissected and the bulbomedullary junction was decompressed.

Results

The planned steps of the operation were performed in all cadavers. The retropharyngeal approach allowed the target region to be accessed easily. The anatomical structures of the anterior craniocervical junction could be identified and dissected. The bulbomedullary junction could be adequately decompressed. No resections of the anterior arch of the atlas were necessary in the odontoidectomy.

Conclusions

Using the full-endoscopic uniportal technique with an anterior retropharyngeal approach, the craniocervical region can be adequately reached, dissected, and decompressed. This is a minimally invasive technique with the known advantages of an endoscopic procedure under continuous irrigation. The retropharyngeal approach allows direct, sterile access. The instruments are available for clinical use and have been established for years in other operations of the entire spine.

Endoscopic Endonasal Resection of the Odontoid Process in a Patient with Chronic Injury of the C1 Transverse Ligament

Atlas dislocation after transverse ligament injury is one of the most rare types of trauma to the upper cervical level. If magnetic resonance imaging of the craniovertebral junction reveals the Kassam line passing through the cervix of the odontoid process, a transnasal approach can be used for surgical treatment. Here, we present a case in which an endoscopic endonasal approach was used to treat chronic traumatic transligamentous atlas dislocation. A 26-year-old male underwent two-stage surgical treatment; during the first stage, posterior decompression and fixation were performed under halo immobilization. In the second stage, a transnasal endoscopic approach to the odontoid process was used. A transnasal approach permitted complete decompression of the medulla oblongata and facilitated early extubation of the patient without any postoperative complications such as respiratory or pharyngopalatine deficiency. The patient was discharged in good condition 9 days after the surgery.

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.

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 craniocervical junction: the importance of anterior C1 arch preservation or its reconstruction

We report our experience with the endoscopic endonasal approaches (EEA) for different craniocervical junction (CCJ) disorders to analyse outcomes and demonstrate the importance and feasibility of anterior C1 arch preservation or its reconstruction. Between January 2009 and December 2013, 10 patients underwent an endoscopic endonasal approach for different CCJ pathologies at our Institution. In 8 patients we were able to preserve the anterior C1 arch, while in 2 post-traumatic cases we reconstructed it. The CCJ disorders included 4 cases of irreducible anterior bulbo-medullary compression secondary to rheumatoid arthritis or CCJ anomalies, 4 cases of inveterate fractures of C1 and/or C2 and 2 tumours. Pre- and postoperative neuroradiological evaluation was always obtained by magnetic resonance imaging (MRI), computed tomographic (CT) scanning and dynamic cranio-vertebral junction x-ray. Pre- and postoperative neurologic disability assessment was obtained by Ranawat classification for patients with rheumatoid arthritis and by Nurick classification for the others. At a mean follow-up of 31 months (range: 14-73 months), an improvement of at least one Ranawat or Nurick classification level was observed in 6 patients, while in another 4 patients neurological conditions were stable. Radiological follow-up revealed an adequate bulbo-medullary decompression in all patients and a regular bone fusion in cases of C1 and/or C2 fractures. In all patients spinal stability was preserved and none required subsequent posterior fixation. The endoscopic endonasal surgery provided adequate exposure and a low morbidity minimally invasive approach to the antero-medial located lesions of the CCJ, resulting in a safe, effective and well-tolerated procedure. This approach allowed preservation of the anterior C1 arch and the avoidance of a posterior fixation in all patients of this series, thus preserving the rotational movement at C0-C2 segment and reducing the risk of a subaxial instability development.

Variations of mucosal-sparing septectomy for endonasal approach to the craniocervical junction

OBJECTIVES/HYPOTHESIS

Recent advances in surgical techniques have rendered the craniocervical junction (CCJ) accessible transnasally. Endoscopic endonasal transclival and transodontoid approaches are routinely performed in leading skull base centers. Usually, these approaches involve a posterior bony and mucosal septectomy, which may compromise the vascularized pedicled nasoseptal flap (PNSF), a robust reconstructive option for repair of large skull base defects. With the possibility of an intraoperative cerebrospinal fluid leak and the reported success of the PNSF for repair of these defects, preserving the integrity of the PNSF is beneficial during the endoscopic endonasal approach to the CCJ. We describe three new variations/refinements of the endoscopic endonasal approach to the CCJ that preserve the mucosal integrity of the posterior nasal septum and PNSF.

METHODS

Photo and video documentation of cadaveric dissections.

RESULTS

The steps required for the different variations in approaching the CCJ are demonstrated. These three options are: 1) nonopposing Killian incisions with submucosal elevation of PNSFs laterally under the inferior turbinates (the PNSFs are retracted laterally and left attached superiorly onto the nasal septum and laterally under the inferior turbinate); 2) bilateral non-opposing PNSFs tucked beneath their respective middle turbinate or into the sphenoid sinus; and 3) a hybrid approach combining option 1 performed on one side and option 2 on the contralateral side. All three options allowed for a mucosal-sparing septectomy to provide ample access to the CCJ.

CONCLUSION

These variations/refinements of the mucosal-sparing approach to the CCJ allowed adequate surgical access with sufficient maneuverability while preserving both PNSFs.

LEVEL OF EVIDENCE

NA. Laryngoscope, 126:2220-2225, 2016.

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.

Quantification and comparison of neurosurgical approaches in the preclinical setting: literature review

There is a growing awareness of the need for evidence-based surgery and of the issues that are specific to research in surgery. Well-conducted anatomical studies can represent the first, preclinical step for evidence-based surgical innovation and evaluation. In the last two decades, various reports have quantified and compared neurosurgical approaches in the anatomy laboratory using different methods and technology. The aim of this study was to critically review these papers. A PubMed and Scopus search was performed to select articles that quantified and compared different neurosurgical approaches in the preclinical setting. The basic characteristics that anatomically define a surgical approach were defined. Each study was analyzed for measured features and quantification method and technique. Ninety-nine papers, published from 1990 to 2013, were included in this review. A heterogeneous use of terms to define the features of a surgical approach was evident. Different methods to study these features have been reported; they are generally based on quantification of distances, angles, and areas. Measuring tools have evolved from the simple ruler to frameless stereotactic devices. The reported methods have each specific advantages and limits; a common limitation is the lack of 3D visualization and surgical volume quantification. There is a need for a uniform nomenclature in anatomical studies. Frameless stereotactic devices provide a powerful tool for anatomical studies. Volume quantification and 3D visualization of the surgical approach is not provided with most available methods.

Videoassisted anterior surgical approaches to the craniocervical junction: rationale and clinical results

PURPOSE

In this narrative review, we aim to give an update on the anatomic fundamentals of endoscopic assisted surgery to the craniocervical junction (transnasal, transoral and transcervical), and to report on the available clinical results.

METHODS

A non-systematic review and reporting on the anatomical and clinical results of endoscopic assisted approaches to the craniocervical junction (CVJ) is performed.

RESULTS

Pure endonasal and cervical endoscopic approaches still have some disadvantages, including the learning curve and the lack of 3-dimensional perception of the surgical field. Endoscopically assisted transoral surgery with 30° endoscopes represents an emerging alternative to standard microsurgical techniques for transoral approaches to the anterior CVJ. Used in conjunction with traditional microsurgery and intraoperative fluoroscopy, it provides a safe and improved method for anterior decompression with or without a reduced need for extensive soft palate splitting, hard palate resection, or extended maxillotomy.

CONCLUSIONS

Transoral (microsurgical or video-assisted) approach with sparing of the soft palate still remains the gold standard compared to the "pure" transnasal and transcervical approaches due to the wider working channel provided by the former technique. Transnasal endoscopic approach alone appears to be superior when the CVJ lesion exceeds the upper limit of the inferior third of the clivus. Combined transnasal and transoral procedures can be tailored according to the specific pathological and radiological findings.

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.

Mucosal-sparing posterior septectomy for endoscopic endonasal approach to the craniocervical junction

Recent technological advances and developments in surgical technique have made the craniocervical junction (CCJ) accessible through the transnasal surgical corridor. Endoscopic endonasal transclival and transodontoid approaches have been previously described in the literature. Traditionally, these approaches entail a posterior bony and mucosal septectomy. This posterior bony and mucosal septectomy can compromise the integrity of the posterior septum and damage the vascularized pedicled nasoseptal flap (PNSF), a robust reconstructive option. With the possibility of an intraoperative cerebrospinal fluid (CSF) leak and the reported success of the PNSF for repair of these defects, preserving the integrity of the PNSF is beneficial during the endoscopic endonasal approach to the CCJ. Here, we present a new variation which preserves the mucosal integrity of the posterior nasal septum and PNSF. This mucosal-sparing variation of the traditional endoscopic endonasal transclival and transodontoid approaches allows for the preservation of posterior mucosal nasoseptal integrity, and salvages a reconstructive option for future usage. This is accomplished at no expense to visualization, surgical access, or maneuverability.

Endonasal Access to the Upper Cervical Spine: Part 2-Cadaveric Analysis

Objectives The study aims to determine factors that augment endonasal exposure of the cervical spine. Setting We used fluoroscopy and endoscopy to study endonasal visualization of the upper cervical spine. Participants Ten cadavers with normal anatomy were studied. Main Outcome Measures Endoscopic visualization was simulated with projected lines from an endoscope to the cervical spine in multiple positions. Results Neck position alone did not affect the extent of endonasal exposure of the upper cervical spine, although there was a trend correlating the extended neck position with more caudal exposure. The greatest impact was with concurrent use of a 30-degree endoscope and neck extension, and more caudal access was achieved by tilting the endoscope against the piriform aperture, using the posterior tip of the hard palate as the fulcrum. Conclusions Concurrent use of a 30-degree endoscope and neck extension increased the degree of exposure down the cervical spine. Maximum endonasal exposure of the upper cervical spine was obtained by maneuvering instruments at the fulcrum of the posterior hard palate and the nares, rather than changing the position of the neck alone. These results complement radiographic morphometric data in Part 1 of this study for preoperative assessment and surgical planning.

Endoscopic transcervical anterior release and posterior fixation in the treatment of irreducible vertical atlantoaxial dislocation

Vertical atlantoaxial dislocation is a type of atlantoaxial instability with upper cervical spinal cord compression. The transoral ondontoid resection with posterior fixation is the gold standard for ventral decompression. Results are satisfying though surgery can be challenging due to its invasiveness. The endoscopic transcervical anterior release could provide sufficient ventral decompression with less collateral damage. In the illustrative case, anatomic reduction was achieved with significant improvement in neurological function and radiographic parameters. Endoscopic transcervical anterior release and posterior fixation appears to be a viable and interesting alternative for the treatment of vertical atlantoaxial dislocation in properly selected individuals, and its implementation could significantly reduce the post-surgical complications.

Endonasal access to the upper cervical spine, part one: radiographic morphometric analysis

Objectives To determine the anatomical relationships that may influence endonasal access to the upper cervical spine. Setting We retrospectively analyzed computed tomography of 100 patients at a single institution. Participants Participants included adults with imaging of the hard palate, clivus, and cervical spine without evidence of fracture, severe spondylosis, or previous instrumentation. Main Outcome Measures Morphometric analyses of hard palate length and both distance and angle between the hard palate and odontoid process were based on radiographic measurements. Descriptive zones were assigned to cervical spine levels, and endoscopic visualization was simulated with projected lines at 0, 30, and 45 degrees from the hard palate to the cervical spine. Results We found an inverse relationship between hard palate length and the lowest zone of the cervical spine potentially visualized by nasal endoscopy. The distance between the posterior tip of the hard palate and the odontoid tip, and the angle formed between the two, directly influenced the lowest possible cervical exposure. Conclusions Radiographic relationships between hard palate length, distance to the odontoid, and the angle formed between the two predict the limits of endonasal access to the cervical spine. These results are supported by cadaveric data in Part Two of this study.

Endoscopic transnasal odontoidectomy to treat basilar invagination with congenital osseous malformations

PURPOSE

Transoral resection of the odontoid has been accepted as a standard procedure to decompress the cervicomedullary junction during the past several decades. The endoscopic transnasal odontoidectomy is emerging as a feasible surgical alternative to conventional microscopic transoral approach. In this article, we describe several operative nuances and pearls from our experience about this approach, which provided successful decompression.

METHODS

From September 2009 to April 2010, three consecutive patients with basilar invagination, of which the etiology was congenital osseous malformations, underwent endoscopic transnasal odontoidectomy. All patients presented with myelopathy. The last two cases also received occipitocervical fixation and bone fusion during the same surgical episode to ensure stability.

RESULTS

All the patients were extubated after recovery from anesthesia and allowed oral food intake the next day. Cerebrospinal fluid rhinorrhea was found in the second case and cured by continuous lumber drainage of cerebrospinal fluid. No infection was noted. The average follow-up time was more than 24 months. Remarkable neurological recovery was observed postoperative in all patients.

CONCLUSION

The endoscopic transnasal odontoidectomy is a feasible approach for anterior decompression of pathology at the cervicomedullary junction. The advantages over the standard transoral odontoidectomy include elimination of risk of tongue swelling and teeth damaging, improvement of visualization, alleviation of prolonged intubation, reduction of need for enteral tube feeding and less risk of affecting phonation. The minimally invasive access and faster recovery associated with this technique make it a valid alternative for decompression of the ventral side of the cervicomedullary junction.

Morphometric measurements of the anterior skull base for endoscopic transoral and transnasal approaches

The objective of this study is to determine the bony limits of the transnasal and transoral approaches to the anterior skull base. The data we present are meant to assist surgeons in preoperative planning for lesions of the sella, clivus, foramen magnum, and odontoid. Using precise measurements undertaken on 41 high-resolution computed tomography scans from patients at the University of Pennsylvania without any history of sinus or sellar pathology, we sought to define the bony limits of transoral and transnasal approaches. Direct measurements and calculated angles were used to assess the dimensions of the anterior skull base. Using our measurements, a transnasal approach can reach an average of 22.5 mm below the plane of the hard palate to the body of C2, and a transoral route can reach 38 mm above the basion along the length of the clivus. Analysis of variance demonstrated no significant differences when subjects were grouped based on race or gender. The measurements outlined within this article help to define the relative dimensions necessary for adapted transoral and transnasal skull base surgeries.

Endoscopic transnasal odontoid resection to decompress the bulbo-medullary junction: a reliable anterior minimally invasive technique without posterior fusion

PURPOSE

Anterior decompression of the craniovertebral junction is reserved to patients with irreducible ventral bulbo-medullary lesions and rapidly deteriorating neurological functions. Classically performed through the transoral approach, the exposure of this region can be now achieved by a minimally invasive endonasal endoscopic approach (EEA).

METHODS

Four patients with irreducible, anterior bulbo-medullary compression due to rheumatoid pannus and basilar invagination were enrolled. The imaged-guided EEA was used to resect the odontoid process, trying to preserve the C1 anterior arch.

RESULTS

Neurological improvement and adequate bulbo-medullary decompression were obtained in all patients. In two cases, anterior C1 ring was preserved. These patients did not required a posterior fusion.

CONCLUSIONS

Compared with the standard transoral technique, the EEA provides the same good exposure but with potentially less complications. The preservation of the anterior C1 arch can contribute to avoid cranial settling and posterior fusion with its related risk of subaxial instability.

The importance of platybasia and the palatine line in patient selection for endonasal surgery of the craniocervical junction: a radiographic study of 12 patients

OBJECTIVE

Ventral decompressive surgery of the craniocervical junction is performed to manage a variety of conditions, including basilar invagination, which can be associated with platybasia. We have noted that the anatomic changes of platybasia could affect the height of the odontoid over a line drawn along the nasal cavity floor, the palatine line (PL). This anatomic change may influence the use of nasal endoscopic surgery for patients with platybasia who also have basilar invagination. We investigated whether the height of the craniocervical junction is elevated over the PL in patients with and without platybasia.

METHODS

We conducted a retrospective review of consecutive craniovertebral junction surgical cases during a 14-month period. During that time we treated 12 patients, including 4 with platybasia and 8 without. The average age was 50 years (range, 18-64 years). Preoperative and postoperative radiographic images were evaluated and charts reviewed.

RESULTS

The mean height of the odontoid over the PL without platybasia was 3.5 mm (range, 0-19.0 mm). In those with platybasia, it was 15.5 mm (range, 7-26.0 mm; P=.021). There was a statistically significant increase in the height of the clival tip and C1 ring in patient with platybasia as well.

CONCLUSIONS

Platybasia is associated with an increase in the odontoid and craniocervical junction over the PL. This increase in height has implications for endoscopic approach selection in patients with platybasia. Platybasia patients with basilar invagination may be better suited to a transnasal approach.

Degenerative Pannus Mimicking Clival Chordoma Resected via an Endoscopic Transnasal Approach

Lesions of the lower clivus represent a technically challenging subset of skull base disease that requires careful treatment. A 75-year-old woman with tongue atrophy was referred for resection of a presumed clival chordoma. The lesion was resected via an endoscopic transnasal transclival approach with no complications. Pathology revealed only chronic inflammatory tissue consistent with a degenerative pannus. Degenerative pannus should be included in the differential diagnosis of lower clival extradural lesions. The endoscopic transnasal transclival corridor should be considered for resection of such lesions as an alternative to larger, more morbid, traditional skull base approaches.

Anterior endoscopically assisted transcervical reconstruction of the upper cervical spine

Anterior decompression and/or reconstruction can be an effective method for the surgical treatment of ventral spinal cord compression in the upper cervical spine. Options for traditional surgical approaches include transoral, transnasal, and extraoral. The risk and complex anatomy with the aforementioned approaches induces surgeons to use the transcervical route to expose the upper cervical spine. A traditional transcervical approach, however, carries the disadvantages of a deep operative field and steep trajectory. We performed a new endoscopically assisted method of anterior reconstruction for the treatment of ventral lesions in upper cervical spine. Six patients were treated from January 2005 to December 2007. Among those six patients, three patients were diagnosed with fixed atlantoaxial dislocations, two with plasmacytomas, and one with a giant cell tumor. All patients were treated by combined endoscopically assisted anterior reconstruction and posterior fusion. One patient with a fixed atlantoaxial dislocation sustained a cerebrospinal fluid leak in the immediate postoperative period, which spontaneously resolved 7 days after surgery. None of the patients had any neurologic deterioration following surgery, nor did any require admission to the intensive care unit for any reason. At the final follow-up, all patients were found to have evidence of a successful clinical outcomes and radiographic fusion. There were no implant failures or radiographic signs of implant migration or loosening. In conclusion, this study demonstrates that an anterior transcervical decompression using endoscopic visualization combined with a posterior arthodesis can achieve good clinical and radiographic outcomes.

Endoscopic transnasal resection of the odontoid: case series and clinical course

The transoral route is the gold standard for odontoid resection. Results are satisfying though surgery can be challenging for patients and surgeons due to its invasiveness. A less invasive transnasal approach could provide a sufficient extent of resection with less collateral damage. The technique of transnasal endoscopic odontoid resection is demonstrated by a case series of three patients. A fully endoscopic transnasal odontoid resection was conducted by use of CT-based neuronavigation. A complete odontoid resection succeeded in all patients. Symptoms such as dysarthria, swallowing disturbance, salivary retention, myelopathic gait disturbances, neck pain, and tetraparesis improved in all patients markedly. Transnasal endoscopic odontoid resection is a feasible alternative to the transoral technique. It leaves the oropharynx intact, which could result in lower approach related complications especially in patients with bulbar symptoms.