Endoscopic endonasal transclival approach

• Modified graded skull base reconstruction for intraoperative CSF leak repair in endoscopic endonasal surgeries: a single-surgeon experience in initial years of practice and nuances in the early learning curve
• Pons herniation after skull base chondrosarcoma surgery: A rare complication after transclival endoscopic endonasal approach
• Preservation of Olfactory Function After Pediatric Endoscopic Endonasal Skull Base Surgery with Nasoseptal Flap Reconstruction
• Endoscopic endonasal intradural pituitary hemitransposition via the transtuberculum/transclival approach for retroinfundibular interpeduncular fossa craniopharyngiomas
• Transclival endoscopic approach for prepontine cistern neurocysticercosis causing trigeminal neuralgia: illustrative case
• Commentary: Endoscopic, Endonasal, Transsphenoidal, Transclival Approach for Resection of Odontoid Process: 2-Dimensional Operative Video
• Endoscopic, Endonasal, Transsphenoidal, Transclival Approach for Resection of Odontoid Process: 2-Dimensional Operative Video
• Development and Validation of a Novel Human-Fixed Cadaveric Model Reproducing Cerebrospinal Fluid Circulation for Simulation of Endoscopic Endonasal Skull Base Surgery

The endoscopic endonasal transclival approach is a surgical technique to access and treat lesions located in the clivus region of the skull base.

1. Endoscopic Endonasal Transsphenoidal Approach:

Endoscopic: This approach involves the use of an endoscope, a thin, flexible tube with a light and camera on its end. The endoscope is inserted through the nostrils to reach the surgical site, eliminating the need for external incisions on the face or head.

2. Transclival Approach:

Clivus Region: The clivus is an area where the basilar artery, brainstem, and other critical structures are located. Accessing lesions in this region can be challenging due to its deep location and proximity to vital structures.

Patient Positioning: The patient is typically positioned supine (lying on their back).

Anesthesia: General anesthesia is administered. Endoscope Insertion: The endoscope is inserted through the nostrils and navigated through the nasal passages to reach the clivus.

Bone Removal: The surgeon may need to remove a portion of the sphenoid bone to access the clivus.

Lesion Treatment: Once access is achieved, the surgeon can visualize and treat the lesion using the endoscope and specialized instruments.

Closure: The surgical site is then closed, and nasal packing may be used temporarily.

Minimally Invasive: The endoscopic transnasal approach is minimally invasive compared to traditional open approaches, leading to potentially faster recovery times and reduced postoperative complications.

Direct Visualization: The endoscope provides a direct and magnified view of the surgical field.

Learning Curve: The procedure requires specialized training in endoscopic skull base surgery.

Anatomical Variability: The anatomy in the clivus region can vary among individuals, requiring a thorough understanding of the patient's unique anatomy.

This approach is part of the broader field of skull base surgery, and its use depends on the specific characteristics of the lesion and the patient. Surgeons carefully evaluate the risks and benefits of this approach for each case to optimize outcomes.

An extended transnasal endoscopic access has to be performed according to a bilateral sphenoethmoidectomy with harvesting of a vascularized septomucosal flap for later skull base reconstruction. In such a way a broad access to the central skull base is gained under endoscopic view, thus allowing removal of the tumor in a four-hand technique with one surgeon holding the endoscope and a sucker while the second surgeon was able to use two instruments. The clivus is reduced by the use of a high-speed drill and Kerrison punches. Tumor removal is performed using curettes and an ultrasound aspirator ¹⁾.

The 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.

Eloy et al. 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 ²⁾.

Endoscopic endonasal transclival approach for clivus chordoma

Endoscopic endonasal transclival approach for petroclival meningioma

Endoscopic endonasal transclival approach for clival chondroma.

Endoscopic endonasal transclival approach for trigeminal schwannoma.

Endoscopic endonasal transclival approach for vertebral artery aneurysm.

Endoscopic endonasal transclival approach for cerebellar arteriovenous malformation.

In a study, the authors presented a rare case of a symptomatic ectopic retrosellar RCC posterior to the pituitary gland, causing extensive clival erosion. The surgical nuances of the wide marsupialization of the cyst through the intraoperative ultrasound-assisted endoscopic endonasal transclival approach are described, and a systematic literature review of intracranial ectopic RCCs is conducted ³⁾.

Corecha Santos et al. describe and evaluate the steps required to perform a combined endoscopic endonasal/transoral transclival transodontoid approach for anterior decompression of the craniovertebral junction.

The endoscopic endonasal transclival transodontoid approach combined with endoscopic transoral decompression was performed on 4 cadaveric specimens. Evaluation of this combined technique; a review of the literature; and the nuances, advantages, and pitfalls are reported.

Adequate wide anterior decompression was achieved in all specimens. This combined approach allowed the preservation of the anterior arch of C1 without injuring the eustachian tube anatomy and avoiding internal carotid artery manipulation.

Mastery of both techniques allows for a safe and comfortable surgical corridor. The transoral and transnasal approaches should not be considered as either/or techniques, but rather as a complement to each other. However, as with all new or developing techniques, there is a steep learning curve, which requires ample training in the skull base laboratory ⁴⁾.

Endoscopic Trans-Clival Approaches - Professor Ramez Kirollos

A 46-year-old woman with a 10-year history of sudden and transitory diplopia and right hemiparesis, followed by five more episodes of mild right hemiparesis. Brain MRI showed a 2.6-cm cavernous malformation in the pons with an exophytic portion in the prepontine cistern. The patient underwent an endoscopic endonasal transclival approach for a complete resection of the lesion. CSF leak was noted and corrected on the sixth postoperative day. The patient progressed with complete motor deficit recovery.

Endoscopic transsphenoidal transclival approaches have been developed and their role is widely accepted for extradural pathologies. Their application to intradural pathologies is still debated but is undoubtedly increasing. Different authors have reported various extracranial, anterior transclival approaches for intradural pathologies. A review of Belotti et al. aimed to provide a historical overview of transclival approaches applied to intradural pathologies. PubMed was searched in October 2018 using the terms transcliv*, cliv* intradural, transsphenoidal transcliv*, transoral transcliv*, transcervical transcliv*, transsphenoidal brainstem, and transoral brainstem. Exclusion criteria included not reporting reconstruction techniques, anatomical studies, reviews without new data, and transcranial approaches. Ninety-one studies were included in the systematic review. Since 1966, transcervical, transoral, transsphenoidal microsurgical, and, recently, endoscopic routes have been used as a corridor for transclival approaches to treat intradural pathologies. Each approach presents a curve that follows Scott's parabola, with evident phases of enthusiasm that quickly faded, possibly due to high post-operative CSF leak rates and other complications. It is evident that the introduction of the endoscope has led to a significant increase in reports of transclival approaches for intradural pathologies. Various reconstruction techniques and materials have been used, although rates of CSF leak remain relatively high. Transclival approaches for intradural pathologies have a long history. We are now in a new era of interest, but achieving effective dural and skull-base reconstruction must still be definitively addressed, possibly with the use of newly available technologies ⁵⁾.

Penetration of the clivus is required for surgical access of the brainstem. The endoscopic transclivus approach is a difficult procedure with high risk of injury to important neurovascular structures.

Cheng et al. undertook a novel anatomical and radiological investigation to understand the structure of the clivus and neurovascular structures relevant to the Extended endoscopic endonasal approach and determine a safe corridor for the penetration of the clivus.

They examined the clivus region in the Computed tomography angiography (CTA) images of 220 adults, magnetic resonance (MR) images of 50 adults, and dry skull specimens of 10 adults. Multiplanar reconstruction (MPR) of the CT images was performed, and the anatomical features of the clivus were studied in the coronal, sagittal, and axial planes. The data from the images were used to determine the anatomical parameters of the clivus and neurovascular structures, such as the internal carotid artery and inferior petrosal sinus.

The examination of the CTA and MR images of the enrolled subjects revealed that the thickness of the clivus helped determine the depth of the penetration, while the distance from the sagittal midline to the important neurovascular structures determined the width of the penetration. Further, data from the CTA and MR images were consistent with those retrieved from the examination of the cadaveric specimens.

The findings provided certain pointers that may be useful in guiding the surgery such that inadvertent injury to vital structures is avoided and also provided supportive information for the choice of the appropriate endoscopic equipment ⁶⁾.

Transsellar-transclival endoscopic endonasal approach allows complete resection of lesions located in the sellar region and infrasellar region with a low rate of complications ⁷⁾.

Lateral extension and previous treatment are factors that could make the surgery more difficult. Intradural extension did not limit the radicality of the removal ⁸⁾.

see Expanded endonasal transclival approach.

Two hundred twelve patients (mean age 47.9 years, 57.1% male) underwent transclival endoscopic endonasal approach (EEA) for lower clivus lesions. In addition to the lower clivus, resection involved the occipital condyle in 14.2% of patients, the foramen magnum in 16.5%, and the atlantooccipital joint (AO) in 1.4%. Quantification of condyle resection revealed complete resection in 3 cases, 75% resection in 8 cases, 50% resection in 6 cases, and 25% resection in 13 cases. Seven of these patients had EEA combined with an open, far lateral approach. In total, 7 patients required arthrodesis following EEA (3.3%), 4 of them after a combined approach. All patients who underwent arthrodesis had primary bone tumors such as chordoma, chondrosarcoma, or osteosarcoma (P = .022). The degree of condyle resection was a significant factor predisposing to occipitocervical instability (P = .001 and P < .001 for 75% and 100% condyle resection, respectively). Use of a combined approach was significantly associated with arthrodesis (P < .001).

EEA resection of the occipital condyles that results in greater than 75% condyle resection or EEA in combination with an open approach significantly increases the risk of AO instability and likely necessitates AO fixation ⁹⁾.

From 2008 to the present time, the inpatient institution has operated on 140 patients with various tumors of the base of the skull, localized to the clivus and anterior region of the posterior cranial fossa (65 men and 75 women). The age of patients ranged from 3 to 74 years. Tumor distribution according to the histopathological features was as follows: chordomas, 103 (73.57%); meningiomas, 12 (8.57%); pituitary adenomas, 9 (6.43%); fibrous dysplasia, 4 (2.86%); cholesteatoma, 3 (2.14%); craniopharyngiomas, 2 (1.43%); plasmacytomas, 2 (1.43%); and other tumors (giant cell tumor, neurohypophyseal glioma, osteoma, carcinoid, chondroma), 5 (3.57%). The tumors had the following size distribution: giant (more than 60 mm), 35 (25%); large (35-59 mm), 83 (59.3%); medium (21-35 mm), 21 (15%); and small (less than 20 mm), 1 (0.7%). In 11 cases, intraoperative monitoring of the cranial nerves was performed (21 cranial nerves were identified).

Upper, middle, and lower transclival approaches provide access to the anterior surface of the upper, middle, and lower neurovascular complexes of the posterior cranial fossa. The chordoma cases were distributed as follows according to the extent of removal: total removal, 68 (66.02%); subtotal removal, 25 (24.27%); and partial removal, 10 (9.71%). The adenomas of the pituitary gland were removed totally in 6 cases, subtotally in 1 case and partially in 2 cases. The meningiomas were removed totally in 1 case, subtotally in 5 cases, and partially in 5 cases, with less than 50% of the tumor removed in 1 case. Other tumors (cholesteatoma, craniopharyngioma, fibrous dysplasia, giant cell tumor, glioma of the neurohypophysis, osteoma, plasmacytoma, carcinoid, and chondroma) were removed totally in 9 cases and subtotally in 7 cases. Postoperative CSF leaks occurred in 9 cases (6.43%) and meningitis in 13 cases (9.29%). Oculomotor disorders developed in 19 patients (13.57%), 12 of which regressed during the period from 4 to 38 days after surgery, and 7 of which were permanent. In 2 cases, surgical treatment had a lethal outcome (1.43%).

The endoscopic endonasal transclival approach can be used to obtain access to the centrally located tumors of the posterior cranial fossa. It is an alternative to transcranial approaches in the surgical treatment of tumors of the clivus. The results of using this approach are comparable with the results of transcranial and transfacial approaches and, in some cases, surpass them in effectiveness. The extended endoscopic endonasal posterior (transclival) approach, considering its minimally invasive nature, allows for radical and low-risk (in terms of postoperative complications and lethality) removal of various skull base tumors of central localization with the involvement and without the involvement of the clivus, which, until recently, were considered to be almost inoperable ¹⁰⁾