Endoscopic image-guided transoral approach to the craniovertebral junction: an anatomic study comparing surgical exposure and surgical freedom obtained with the endoscope and the operating microscope

Correlation Among Syrinx Resolution, Cervical Sagittal Realignment, and Surgical Outcome After Posterior Reduction for Basilar Invagination, Atlantoaxial Dislocation, and Syringomyelia

BACKGROUND

The correlation among syrinx resolution, occipitoaxial sagittal alignment, and surgical outcome in long-term follow-up seems to have not been clarified.

OBJECTIVE

To further explore the relationship between the syrinx resolution and occipitoaxial realignment after posterior reduction and fixation in basilar invagination (BI)-atlantoaxial dislocation (AAD) patients with syringomyelia.

METHODS

A continuous series of 32 patients with BI-AAD and syringomyelia who received direct posterior reduction met the inclusion criteria of this study. Their clinical and imaging data were analyzed retrospectively. Before surgery and at the last follow-up, we used the Japanese Orthopedic Association (JOA) score and the Neck Disability Index (NDI) to assess the neurological status, respectively. The Pearson correlation coefficient and multiple stepwise regression analysis were used to explore the relevant factors that may affect surgical outcomes.

RESULTS

There were significant differences in atlantodental interval, clivus-axial angle, occiput-C2 angle (Oc-C2A), cervicomedullary angle (CMA), subarachnoid space (SAS) at the foramen magnum (FM), syrinx size, NDI, and JOA score after surgery compared with those before surgery. ΔCMA and the resolution rate of syrinx/cord as relevant factors were correlated with the recovery rate of JOA (R 2 = 0.578, P < .001) and NDI (R 2 = 0.369, P < .01). What's more, ΔSAS/FMD (SAS/FM diameter) and ΔOc-C2A were positively correlated with the resolution rate of syrinx/cord (R 2 = 0.643, P < .001).

CONCLUSION

With medulla decompression and occipital-cervical sagittal realignment after posterior reduction and fusion for BI-AAD patients with syringomyelia, the structural remodeling of the craniovertebral junction and occipitoaxial realignment could contribute to syringomyelia resolution.

Transtubular Transoral Approach for Irreducible Ventral Craniovertebral Junction Compressive Pathologies: Surgical Technique and Outcome

Introduction

To investigate the use of a tubular retractor to provide access to the craniovertebral junction (CVJ) sparing the soft palate with the aim of reducing complications associated with traditional transoral approach but yet allowing adequate decompression of the CVJ.

Materials and methods

Twelve consecutive patients with severe myelopathy (JOA-score less than 11) from ventral CVJ compression were operated between 2014-2020 using a tubular retractor assisted transoral decompression.

Results

All patients improved neurologically statistically (p=0.02). There were no posterior pharynx wound infections or rhinolalia. There was one case with incomplete removal of the lateral wall of odontoid and one incidental durotomy.

Conclusions

A Tubular retractor provides adequate access for decompression of the ventral compression of CVJ. As the tubular retractor pushed away the uvula, soft palate and pillars of the tonsils as it docked on the posterior pharyngeal wall, the traditional complications associated with traditional transoral procedures is completely avoided.

Multidisciplinary approach to the craniovertebral junction. Historical insights, current and future perspectives in the neurosurgical and otorhinolaryngological alliance

Historically considered as a nobody’s land, craniovertebral junction (CVJ) surgery or specialty recently gained high consideration as symbol of challenging surgery as well as selective top level qualifying surgery. The alliance between Neurosurgeons and Otorhinolaringologists has become stronger in the time. CVJ has unique anatomical bone and neurovascular structures architecture. It not only separates from the subaxial cervical spine but it also provides a special cranial flexion, extension, and axial rotation pattern. Stability is provided by a complex combination of osseous and ligamentous supports which allows a large degree of motion. The perfect knowledge of CVJ anatomy and physiology allows to better understand surgical procedures of the occiput, atlas and axis and the specific diseases that affect the region. Although many years passed since the beginning of this pioneering surgery, managing lesions situated in the anterior aspect of the CVJ still remains a challenging neurosurgical problem. Many studies are available in the literature so far aiming to examine the microsurgical anatomy of both the anterior and posterior extradural and intradural aspects of the CVJ as well as the differences in all the possible surgical exposures obtained by 360° approach philosophy. Herein we provide a short but quite complete at glance tour across the personal experience and publications and the more recent literature available in order to highlight where this alliance between Neurosurgeon and Otorhinolaringologist is mandatory, strongly advisable or unnecessary.

Volume of Surgical Freedom: The Most Applicable Anatomical Measurement for Surgical Assessment and 3-Dimensional Modeling

Surgical freedom is the most important metric at the disposal of the surgeon. The volume of surgical freedom (VSF) is a new methodology that produces an optimal qualitative and quantitative representation of an access corridor and provides the surgeon with an anatomical, spatially accurate, and clinically applicable metric. In this study, illustrative dissection examples were completed using two of the most common surgical approaches, the pterional craniotomy and the supraorbital craniotomy. The VSF methodology models the surgical corridor as a cone with an irregular base. The measurement data are fitted to the cone model, and from these fitted data, the volume of the cone is calculated as a volumetric measurement of the surgical corridor. A normalized VSF compensates for inaccurate measurements that may occur as a result of dependence on probe length during data acquisition and provides a fixed reference metric that is applicable across studies. The VSF compensates for multiple inaccuracies in the practical and mathematical methods currently used for quantitative assessment, thereby enabling the production of 3-dimensional models of the surgical corridor. The VSF is therefore an improved standard for assessment of surgical freedom.

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.

Contralateral Transfalcine Versus Ipsilateral Anterior Interhemispheric Approach for Midline Arteriovenous Malformations: Surgical and Anatomical Assessment

BACKGROUND

The contralateral anterior interhemispheric approach (CAIA) is considered to provide surgical advantages to access deep midline lesions: wider working angle, gravity enhanced dissection and retraction, more efficient lighting, and ergonomics. Our team has previously published on the merits of using a contralateral trajectory for medial frontoparietal arteriovenous malformations (AVMs) compared with the conventional anterior interhemispheric approach (IAIA). In this article, we compare the IAIA and CAIA for the resection of medial frontoparietal AVMs using quantitative surgical and anatomical analysis.

METHODS

Two models were designed mimicking the most common features of midline AVMs. The CAIA and IAIA were performed bilaterally in 10 specimens. Variables to compare technical feasibility (surgical window [SW] and surgical freedom [SF], target exposure, and angle of attack) were independently assessed using stereotactic navigation. The average SW, SF, and angle of attack were compared with the Student t test. Significance threshold was set at 0.05.

RESULTS

The CITA and IAIA were similar in terms of SW, target exposure, and SF in the superior aspect of the AVM. In the depth of the interhemispheric fissure, the CAIA was significantly superior to IAIA in both AVM models: 77% wider AA for the inferior aspect of the AVM (P < 0.01) and greater SF for the draining vein (54%, P = 0.01), ipsilateral (98%, P = 0.02), and contralateral ACA (117%, P < 0.01).

CONCLUSIONS

This study suggests technical superiority of the CAIA for the resection of deep midline AVMs. No objective difference was noted in the superficial areas of our models, denoting that IAIA is a safer choice for superficial AVMs. Our results set the foundation for further clinical analysis comparing both approaches.

Endoscopic Transnasal Odontoidectomy

Transoral microscopic odontoidectomy followed by posterior fixation has been accepted as a standard procedure to treat nonreducible basilar invagination during the half past century. In recent years, the development of endoscopic techniques has raised challenges regarding the traditional treatment algorithm. The endoscopic transnasal odontoidectomy is a feasible and effective method in the treatment of irreducible ventral cervicomedullary junction compression, which has several advantages over the transoral approach. The endoscopic odontoidectomy includes transnasal, transoral, and transcervical approaches. The 3 different approaches for endoscopic odontoidectomy present complementary advantages and limitations. The necessity of posterior fixation after odontoidectomy should be considered in every single case on the basis of the peculiar anatomic and clinical conditions.

Endoscopic Approaches to the Craniovertebral Junction

The endoscopic endonasal approach provides a direct surgical trajectory to anteriorly located lesions at the craniovertebral junction. The inferior limit of surgical exposure is predicted by the nasopalatine line, and the lateral limit is demarcated by the lower cranial nerves. Endoscopic endonasal odontoidectomy allows preservation of the soft palate, and patients can restart an oral diet on the first postoperative day. Treating the condition at the craniovertebral junction using this approach requires careful preoperative planning and endoscopic endonasal surgical experience with a 2-surgeon 4-handed approach combining expertise in otolaryngology and neurosurgery.

Quantitative analysis of surgical exposure and surgical freedom to the anterosuperior pons: comparison of pterional transtentorial, orbitozygomatic, and anterior petrosal approaches

Surgical approaches to the pons lump together different areas of the pons, such as the anterosuperior and the anteroinferior pons. These areas are topographically different, and different approaches may be best suited for one or the other area. We evaluated the exposure of the anterosuperior pons using different surgical approaches. We quantify the surgical exposure and surgical freedom to the anterosuperior pons afforded by the pterional transtentorial (PT), the orbitozygomatic with anterior clinoidectomy (OZ), and the anterior petrosal (AP) approaches. Five embalmed cadaver heads were used. The three approaches were executed on each side, for a total of 30 approaches. The area of maximal exposure of the anterosuperior pons was measured with the aid of neuronavigation. We also evaluated the feasible angles of approach in the vertical and horizontal planes. We were able to successfully expose the anterosuperior pons using all the selected approaches. In the PT and OZ approaches, mobilization of the sphenoparietal sinus can prevent over-retraction of the temporal bridging veins, while use of the endoscope can help in preserving the integrity of the fourth nerve while cutting the tentorium. The mean exposure area was largest for the AP and smallest for the PT; the surgical freedom was similar among all the approaches. However, there was no statistically significant difference among all the approaches in the exposure area or in the surgical freedom. There is no significant difference among the three evaluated approaches in exposure of the anterosuperior pons.

Experimental Endoscopic Angular Domains of Transnasal and Transoral Routes to the Craniovertebral Junction: Light and Shade

STUDY DESIGN

We investigate on the surgical reliability of nasal palatine line for the transnasal approach and introduce a conceptually analogue radiological line as a reliable predictor of the maximal superior extension of the transoral approach. We have also compared radiological and surgical lines to find possible radiological references points to predict preoperatively the maximal extent of superior dissection for the transoral approach.

OBJECTIVE

After comparing the surgical exposition angle and the working channel volume of both the approaches in our previous article, now we compare the radiological (theoretical) with the "surgical" (effective) Nasopalatine line and the latter with the recently introduced Nasal Axial Line. We conceived a radiological line with a similar significance for the transoral approach and we called it Mandibulopalatine line; then we compared the radiological with the "surgical" one.

SUMMARY OF BACKGROUND DATA

Endoscopy represents both an alternative and a useful complement to the standard microsurgical approach to the anterior craniovertebral junction (CVJ). Both the surgical routes have a limitation caused by the hard palate.

METHODS

Ten fresh nonperfused cadavers were studied. Transnasal and transoral linear and angled exposure of the CVJ were evaluated by means of X-ray and CT scan in the sagittal plane.

RESULTS

The angular difference between the radiological and surgical transoral endoscopic lines was significantly smaller compared with the difference between the radiological and surgical transnasal lines. Finally we found how to calculate preoperatively the "surgical" (effective) Mandibulopalatine line by a simple lateral preoperative radiological study of the CVJ.

CONCLUSION

Naso-axial line is confirmed to be a reliable preoperative predictor of the maximal extent of inferior dissection for transnasal approach. Surgical Palatine Inferior dental Arch line will draw the maximal extent of superior dissection for the transoral approach with simple lateral head X-ray examination by open mouth.

LEVEL OF EVIDENCE

3.

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.

Ventral Decompression in Chiari Malformation, Basilar Invagination, and Related Disorders

Ventral brainstem compression is an uncommon clinical diagnosis seen by pediatric neurosurgeons and associated with Chiari malformation, type I. Presenting clinical symptoms often include headaches, lower cranial neuropathies, myelopathy, central sleep apnea, ataxia, and nystagmus. When ventral decompression is required, both open and endoscopic transoral/transnasal approaches are highly effective.

The 20-item prosopagnosia index (PI20): a self-report instrument for identifying developmental prosopagnosia

Self-report plays a key role in the identification of developmental prosopagnosia (DP), providing complementary evidence to computer-based tests of face recognition ability, aiding interpretation of scores. However, the lack of standardized self-report instruments has contributed to heterogeneous reporting standards for self-report evidence in DP research. The lack of standardization prevents comparison across samples and limits investigation of the relationship between objective tests of face processing and self-report measures. To address these issues, this paper introduces the PI20; a 20-item self-report measure for quantifying prosopagnosic traits. The new instrument successfully distinguishes suspected prosopagnosics from typically developed adults. Strong correlations were also observed between PI20 scores and performance on objective tests of familiar and unfamiliar face recognition ability, confirming that people have the necessary insight into their own face recognition ability required by a self-report instrument. Importantly, PI20 scores did not correlate with recognition of non-face objects, indicating that the instrument measures face recognition, and not a general perceptual impairment. These results suggest that the PI20 can play a valuable role in identifying DP. A freely available self-report instrument will permit more effective description of self-report diagnostic evidence, thereby facilitating greater comparison of prosopagnosic samples, and more reliable classification.

Anterior video-assisted approach to the craniovertebral junction: transnasal or transoral? A cadaver study

BACKGROUND

Endoscopy represents both an alternative and useful complement to the standard microsurgical approach to the anterior craniovertebral junction (CVJ). Nevertheless, few studies provide an experimental comparison between transnasal and transoral endoscopic control on CVJ. We compared the surgical exposition angle and the working channel volume of both the transnasal and transoral approaches in the cadaver.

METHODS

Eleven fresh non-perfused cadavers were studied. Transnasal and transoral linear and angled exposure of the CVJ were evaluated by means of X-ray and CT scan both in sagittal and lateral planes.

RESULTS

The transoral endoscopic surgical exposition was wider compared with the transnasal in anterior and lateral projections:(1)in the sagittal plane, both in vertical exposition (transnasal inferior to transoral from 5.89 % to 76.48 %, average 35.89 %) and in vertical surgical angle (from 22 % to 77.42 %, average 56.53 %); (2)in the coronal plane, both in coronal exposition (transnasal inferior to transoral from 50.77 % to 83.88 %, average 70.34 %) and in coronal surgical angle (from 65.58 % to 86.71 %, average 76.70 %). The sagittal surgical domain was found to spanning from the inferior third of the clivus to C3 with the transoral and from the middle third of the clivus to the nasopalatal line (NPL) with the transnasal approach. The overlapping surgical domain area was found to be the inferior third of the clivus.

CONCLUSIONS

The endoscope assisted transoral approach allows a better surgical control of the CVJ. It provides a better CVJ exposure, in sagittal and transverse planes, providing a larger working channel and an easier manoeuvrability. The transnasal approach is limited in caudal direction down to the NPL, otherwise the transoral approach is limited in the rostral direction with a maximum to the foramen magnum in normal specimen. In every individual case, pros and cons of the appropriate approach have to be taken into account as well as the choice of a combined transnasal and transoral approaches strategy.

The influence of cervical spine position on the three anterior endoscopic approaches to the craniovertebral junction: an imaging study

BACKGROUND CONTEXT

Three endoscopic anterior approaches, the transnasal, transoral, and transcervical approaches, are used for ventral lesions of the craniovertebral junction and have been compared regarding surgical working distances and approach angles. However, how the position of the cervical spine influences the depths of surgical corridors and approach angles for the three approaches has not been evaluated.

PURPOSE

To evaluate the depths of surgical corridors and the approach angles for the three endoscopic approaches, taking the influence of cervical spine position into account.

STUDY DESIGN

A radiographic study comparing three anterior endoscopic approaches to the craniovertebral junction.

PATIENT SAMPLE

Cervical extension and flexion radiographs for 34 patients and cross-sectional computed tomography scans for 30 additional patients were assessed.

OUTCOME MEASURES

The depths of the surgical corridors and the approach angles for the three endoscopic approaches in the midsagittal planes.

METHODS

We determined the mean angles of the surgical trajectories for the endoscopic transoral and transcervical approaches on cervical extension and flexion radiographs. In addition, we measured the depths of the surgical corridors and the approach angles for the three approaches in the midsagittal plane.

RESULTS

The average depths of surgical corridors were as follows: endonasal, 93.65 mm; transoral, 85.27 mm; transcervical, 62.97 mm (in extension). The average approach angles were as follows: endonasal, 31.22°; transoral, 30.87°; transcervical, 36.58° (in extension).

CONCLUSIONS

The position of the cervical spine does not influence the surgical convenience of the endoscopic transnasal approach, but it can influence the endoscopic transoral and transcervical approaches, especially the latter. The endoscopic transcervical approach offers several advantages over the endoscopic transoral and endonasal approaches.

Quantitative study on endoscopic endonasal approach to the posterior sino-orbito-cranial interface: implications and clinical considerations

The posterior sino-orbito-cranial interface is a critical area in the skull base since it represents a gateway to deeper vital regions. Quantification of the surgical freedom for any given point/area is an objective method for comparing in a reproducible way different surgical approaches. Three freshly injected cadaver heads (six sides) were dissected under the magnetic navigation control system. The surgical freedom (SF) and the angle of attack of fixed target points were determined from the ipsilateral nasal fossa, from the contralateral nasal fossa (after posterior septectomy), and after an anteromedial maxillotomy (according to the Denker procedure). The mean pre-operative SF value resulted to be 403.07 ± 102.73 mm(2) for the ipsilateral nostril, increasing by 126.97 % for the binostril approach, by 118.45 % for the monolateral nostril approach after anteromedial maxillotomy, and by 310.48 % for the binostril approach after bilateral anteromedial maxillotomy. Laterally extended lesions require an anteromedial maxillotomy, while more medially located lesions can be managed by means of a posterior septectomy. When addressing the posterior sino-orbito-cranial interface, the transnasal binostril approach and anteromedial maxillotomy both increase the SF. The choice between them depends on exact position, relationship and clinical behaviour of the lesion to treat.

A new methodology for laboratory evaluation of neurosurgical approaches based on the volume and shape of the surgical space with a mathematical model to quantify the surgical maneuverability in laboratory settings

We conducted this study to validate the volume/shape of the surgical exposure and to introduce a mathematical model to quantify the maneuverability in a surgical space. We executed the pterional and lateral supraorbital approach four times in fresh cadavers in skull base laboratory. The surgical volumes were filled with a computed tomography (CT)-imageable mixture; CT scans were obtained to evaluate the volume and shape of the surgical space. The volume of the surgical space was 23.60 and 32.90 mL for the lateral supraorbital and pterional approach, respectively, (p < 0.05). The three-dimensional shape of the lateral supraorbital approach was cylindrical and that of the pterional approach pyramidal. The volume of the surgical approach can be used to define, together with other variables, the maneuverability (maneuvering in a surgical volume) by using the following formula [Formula: see text] where M, A, V, and L represent the maneuverability, the degree of the surgical freedom, the volume of the surgical exposure, and the surgical depth, respectively. Volume and shape of the surgical exposure are two objective parameters that can be used to define and contrast different microsurgical approaches in a laboratory setting. The volume of the surgical exposure may be integrated into a mathematical formula defining maneuverability.

Intraoperative computed tomography guidance to confirm decompression following endoscopic endonasal approach for cervicomedullary compression

Introduction Cervicomedullary compression often requires an anterior approach to address the compressive vector. In certain cases an endoscopic endonasal approach (EEA) is ideal for decompression. It is essential that an adequate decompression be achieved and verified before the patient leaves the operating room. The purpose of this study was to evaluate the use intraoperative computed tomography (IO-CT) in assessing the adequacy of decompression. Methods A retrospective chart review revealed 11 cases of EEA odontoid resection IO-CT verification of decompression. Operative reports and review of imaging was used to determine if further decompression was performed following the intraoperative scan. Results Out of 11 EEA cases, 4 (36%) patients showed evidence of residual compression following an initial IO-CT. Further operative decompression was undertaken following the first scan in all cases. A second intraoperative scan was then used to confirm complete decompression. No patient left the operating room with residual compression. Discussion IO-CT provided valuable utility in 36% of the cases after the initial resection was incomplete. The standard fluoroscopic guidance may not provide adequate resolution and enhanced utility like IO-CT.

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.

Endoscope-assisted microsurgical transoral approach to the anterior craniovertebral junction compressive pathologies

At the present time, an update to the classical microsurgical transoral decompression is strongly provided by the most recent literature dealing with the introduction of the endoscopy in spine surgery. In this paper, we present our experience on the endoscope-assisted microsurgical transoral approach to anterior craniovertebral junction (CVJ) compressive pathology. We analysed seven patients (3 paediatrics and 4 adults ranging from 6 to 78 years) operated on for CVJ decompressive procedures using an open access, microsurgical technique, neuronavigation and endoscopy. All techniques mentioned were simultaneously employed. Among the endoscopic routes described in the literature, we have preferred the transoral using 30° endoscopes. In all the cases endoscopy allowed a radical decompression compared to the microsurgical technique alone, as confirmed intraoperatively with contrast medium fluoroscopy. In conclusion, endoscopy represents a useful complement to the standard microsurgical approach to the anterior CVJ; it provides information for a better decompression with no need for soft palate splitting, hard palate resection, or extended maxillotomy. Moreover, intraoperative fluoroscopy helps to recognize residual compression. Virtually, in normal anatomic conditions, no surgical limitations exist for endoscopically assisted transoral approach, compared with the pure endonasal and transcervical endoscopic approaches. In our opinion, the endoscope deserves a role as "support" to the standard transoral microsurgical approach since 30° angulated endoscopy significantly increases the surgical area exposed at the level of the anterior CVJ.

Combined transnasal and transoral endoscopic approaches to the craniovertebral junction

Objectives:

To describe and evaluate a new technique of a combined endoscope-assisted transnasal and transoral approach to decompress the craniovertebral junction.

Materials and Methods:

A retrospective cohort of patients requiring an anterior decompression at the craniovertebral junction over a 12-month period was studied. Eleven patients were identified and included in the study. Eight of the patients had an endoscopic approach [endonasal (2), endooral (2), and combined (4)]. Four of the 8 patients in the endoscopic group had a prior open transoral procedure at other institutions. These 8 patients were compared with a contemporary group of 3 patients who had an open, transoral–transpalatal approach. Charts, radiographic images, and pathologic diagnosis were reviewed. We evaluated the following issues: airway obstruction, dysphagia, velopharyngeal insufficiency (VPI), length of hospital stay (LOS), adequate decompression, and the need for revision surgery.

Results:

Adequate anterior decompression was achieved in all the patients. The endoscopic cohort had a reduced LOS (P = 0.014), reduced need for prolonged intubation/tracheotomy (P =0.024) and a trend toward reduced VPI (P = 0.061) when compared with the open surgery group. None of the patients required a revision surgery.

Conclusion:

Proper choice of endoscopic transnasal, transoral, or combined approaches allows anterior decompression at the craniovertebral junction, while avoiding the need to split the palate. A combined transnasal–transoral approach appears to reduce procedure-related morbidity compared with open, transoral, and transpalatal surgeries.