Endoscopic Endonasal Transclival Approach Research Articles

Endoscopic endonasal transclival clipping of a cerebellar arteriovenous malformation feeding vessel and associated aneurysm; a 2D operative video

Positioned along the ventral surface of the pons, proximal superior cerebellar artery (SCA) aneurysms account for only 1.7% of all intracranial aneurysms [1]. Unlike more commonly encountered basilar artery aneurysms, patients often experience good outcomes when treated via endovascular coiling or surgical clipping [1,2]. These lesions frequently have a lateral projection and paucity of perforator arteries [2]. With further development of endoscopic endonasal techniques, access to this region is possible via a direct frontal exposure to the ventral brainstem, basilar artery and branching vessels. To date, there are only a limited number of reports describing an endoscopic endonasal transclival (EETC) approach for surgical clipping [3–5]. In this operative video, we detail the surgical clipping of a cerebellar arteriovenous malformation feeding vessel and an associated aneurysm using the EETC approach in a 59-year-old woman who presented with sudden onset of a severe headache. The feeding vessel and aneurysm’s midline location, just below the take-off of the SCA made it a good candidate for this surgery. Major steps included in this video include 1) transsphenoidal exposure of and subsequent drilling of the clivus, 2) dural opening into the pre-pontine cistern and dissection of the aneurysm, 3) clipping of the aneurysm, and 4) multi-layered closure of the skull base defect. Overall, the patient tolerated the procedure well and was found to have no residual filling of the aneurysm or the AVM feeding vessel at 2-year follow-up. EETC is a viable surgical option for the treatment of aneurysm located along the midline of the pre-pontine cistern.

A rare case of multifocal chordoma involving the lower clivus and multiple spine levels: illustrative case.

Chordomas are rare bone tumors originating from notochord remnants with a predilection for the median axis of the body, primarily in the sacrococcygeal spine, skull base, and cervical spine. This paper presents the first reported case of simultaneous multilevel chordomas with various enhancements. A 40-year-old woman presented with right-sided otalgia, headache, nasal obstruction, and facial pressure. The patient's head and spinal magnetic resonance imaging (MRI) demonstrated a midline lesion in the clivus, C2, and T1-5 spinal levels. All lesions were T1 isointense and T2 hyperintense, consistent with chordoma. Interestingly, the clivus lesion was enhancing, whereas the C2 lesion was only slightly enhancing, and the rest of the lesions showed no enhancement. The patient underwent endoscopic endonasal transclival approach surgery for the clival lesion, followed by radiation to the surgical bed and the C2 lesion. The remaining lesions were monitored. Follow-up imaging showed stable disease in the C2 lesion and other lower lesions. The patient's severe pain in the posterior cervical spine was managed with cervical fusion, pain management, and physical therapy. This case underscores the importance of comprehensive spinal MRI in patients with chordomas, as multiple concurrent primaries may be present. The article summarizes the fundamental distinctions between ecchordosis physaliphora and chordoma and casts doubt on the capacity to always differentiate them.

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Endoscopic Endonasal Middle-Inferior Clivectomy, Odontoidectomy, and Far-Medial Approach

Abstract Introduction The clival, paraclival, and craniocervical junction regions are challenging surgical targets. To approach these areas, endoscopic endonasal transclival approaches (EETCAs) and their extensions (far-medial approach and odontoidectomy) have gained popularity as they obviate manipulating and working between neurovascular structures. Although several cadaveric studies have further refined these contemporary approaches, few provide a detailed step-by-step description. Thus, we aim to didactically describe the steps of the EETCAs and their extensions for trainees. Methods Six formalin-fixed cadaveric head specimens were dissected. All specimens were latex-injected using a six-vessel technique. Endoscopic endonasal middle and inferior clivectomies, far-medial approaches, and odontoidectomy were performed. Results Using angled endoscopes and surgical instruments, an endoscopic endonasal midclivectomy and partial inferior clivectomy were performed without nasopharyngeal tissue disruption. To complete the inferior clivectomy, far-medial approach, and partially remove the anterior arch of C1 and odontoid process, anteroinferior transposition of the Eustachian–nasopharynx complex was required by transecting pterygosphenoidal fissure tissue, but incision in the nasopharynx was not necessary. Full exposure of the craniocervical junction necessitated bilateral sharp incision and additional inferior mobilization of the posterior nasopharynx. Unobstructed access to neurovascular anatomy of the ventral posterior fossa and craniocervical junction was provided. Conclusion EETCAs are a powerful tool for the skull-base surgeon as they offer a direct corridor to the ventral posterior fossa and craniocervical junction unobstructed by eloquent neurovasculature. To facilitate easier understanding of the EETCAs and their extensions for trainees, we described the anatomy and surgical nuances in a didactic and step-by-step fashion.

The anterolateral triangle as window on the foramen lacerum from transorbital corridor: anatomical study and technical nuances

ObjectiveNeurosurgical indications for the superior eyelid transorbital endoscopic approach (SETOA) are rapidly expanding over the last years. Nevertheless, as any new technique, a detailed knowledge of the anatomy of the surgical target area, the operative corridor, and the specific surgical landmark from this different perspective is required for a safest and successful surgery. Therefore, the aim of this study is to provide, through anatomical dissections, a detailed investigation of the surgical anatomy revealed by SETOA via anterolateral triangle of the middle cranial fossa. We also sought to define the relevant surgical landmarks of this operative corridor.MethodsEight embalmed and injected adult cadaveric specimens (16 sides) underwent dissection and exposure of the cavernous sinus and middle cranial fossa via superior eyelid endoscopic transorbital approach. The anterolateral triangle was opened and its content exposed. An extended endoscopic endonasal trans-clival approach (EEEA) with exposure of the cavernous sinus content and skeletonization of the paraclival and parasellar segments of the internal carotid artery (ICA) was also performed, and the anterolateral triangle was exposed. Measurements of the surface area of this triangle from both surgical corridors were calculated in three head specimens using coordinates of its borders under image-guide navigation.ResultsThe drilling of the anterolateral triangle via SETOA unfolds a space that can be divided by the course of the vidian nerve into two windows, a wider “supravidian” and a narrower “infravidian,” which reveal different anatomical corridors: a “medial supravidian” and a “lateral supravidian,” divided by the lacerum segment of the ICA, leading to the lower clivus, and to the medial aspect of the Meckel’s cave and terminal part of the horizontal petrous ICA, respectively. The infravidian corridor leads medially into the sphenoid sinus. The arithmetic means of the accessible surface area of the anterolateral triangle were 45.48 ± 3.31 and 42.32 ± 2.17 mm2 through transorbital approach and endonasal approach, respectively.ConclusionSETOA can be considered a minimally invasive route complementary to the extended endoscopic endonasal approach to the anteromedial aspect of the Meckel’s cave and the foramen lacerum. The lateral loop of the trigeminal nerve represents a reliable surgical landmark to localize the lacerum segment of the ICA from this corridor. Nevertheless, as any new technique, a learning curve is needed, and the clinical feasibility should be proven.

How I do it: the endoscopic endonasal transclival approach for clipping of the ruptured vertebral artery aneurysm.

Vertebral artery aneurysms account for less than 5% of all cerebral aneurysms. They have a high risk of rupture and are associated with threatening clinical outcomes compared with anterior circulation aneurysms. The endoscopic endonasal transclival approach (EETA) was used. During the temporary clipping, the neck of the aneurysm was dissected, and a permanent clip was applied. The repair of the skull base defect was carried out with the nasoseptal mucoperiosteal flap on the vascular pedicle. The EETA is a feasible alternative for the clipping of the medially located ruptured vertebral artery aneurysm. EETA can be recommended for centers with a large volume of cerebrovascular and endoscopic neurosurgical procedures.

Endoscopic endonasal transclival petroclival meningioma resection.

Petroclival meningiomas are surgically challenging due to the surrounding neurovascular structures. Petroclival meningiomas located inferior to the oculomotor nerve and superior or medial to the abducens nerve are ideal for an endoscopic endonasal transclival approach because this prevents the need to work across cranial nerves, limiting operative risk. The authors present a case of a 45-year-old woman with a growing petroclival meningioma that was distorting the pons. In the video they demonstrate the technique and discuss nuances of petroclival meningioma resection via an endoscopic endonasal transclival approach with posterior clinoidectomy.The video can be found here: https://stream.cadmore.media/r10.3171/2022.1.FOCVID21209

The benefits of inferolateral transtubercular route on intradural surgical exposure using the endoscopic endonasal transclival approach.

Surgical access to the ventral pontomedullary junction (PMJ) can be achieved through various corridors depending on the location and extension of the lesion. The jugular tubercle (JT), a surgically challenging obstacle to access the PMJ, typically needs to be addressed in transcranial exposures. We describe the endoscopic endonasal transclival approach (EETCA) and its inferolateral transtubercular extension to assess the intradural surgical field gained through JT removal. We also complement the dissections with an illustrative case. EETCA was surgically simulated, and the anatomical landmarks were assessed in eight cadaveric heads. Microsurgical dissections were additionally performed along the endoscopic surgical path. Lastly, we present an intraoperative video of the trans-JT approach in a patient with lower clival chordoma. The EETCA allowed adequate extracranial visualization and removal of the JT. The surgical bony window-obtained along the clivus and centered at the JT via the EETCA-measured 11 × 9 × 7 mm. Removal of the JT provided an improved intradural field within the lower third of the cerebellopontine cistern to expose an area bordered by the cranial nerves VII/VIII and flocculus superior and anterior margin of the lateral recess of the fourth ventricle and cranial nerves IX-XI inferiorly, centered on the foramen of Luschka. Removal of the JT via EETCA improves exposure along the lower third of the cerebellopontine and upper cerebellomedullary cisterns. The inferolateral transtubercular extension of the EETCA provides access to the lateral recess of the fourth ventricle, in combination with the ventral midline pontomedullary region.

Basilar Artery Injury During Endonasal Surgery: Stepwise to Control Bleeding.

Intraoperative injury during endoscopic endonasal surgery of the carotid artery has been previously described in the literature. However, the accidental damage of the basilar artery in such scenario is not defined. To define the protocol of action for massive bleeding from an artery in the posterior fossa. The reported patient was diagnosed with a partially calcified clival chordoma featured by a huge intradural component. An endoscopic endonasal transpterygoid transclival approach was selected for the treatment of this tumor. During the surgical procedure, the basilar artery injury was injured, causing intense bleeding. We present and discuss the surgical maneuvers that could save a patient's life after this dramatic complication. Different techniques were performed in order to control the massive bleeding, including injection of hemotastic matrix with thrombin (Floseal©), bipolar coagulation, and vessel reconstruction by means of a vascular clip. Finally, an autologous muscle graft reinforced with an overlying fibrin sealant patch (Tachosil©) was chosen and was an effective technique. Afterwards, the patient was treated with a flow diverter device to occlude an iatrogenic pseudoaneurysm. A monoplegia of the right upper limb was the only remarkable sequel 6 mo after surgery. The muscle graft together with the coordinated action with interventional neuroradiology for the reconstruction of the vessel are possibly the best options to try to preserve the neurological function. In such a scenario, the assumption of potential ischemic events prevails over the intraoperative death of the patient.

Endoscopic Endonasal Transclival Odontoidectomy for Basilar Invagination: Operative Video and Technical Nuances.

Basilar invagination is a congenital or acquired craniovertebral junction abnormality where the tip of the odontoid process projects through the foramen magnum which can cause severe symptomatic compression of the brainstem and spinal cord. If left untreated, patients can develop progressive quadriparesis. Traditionally, basilar invagination can be treated with cervical traction and posterior stabilization. However, in irreducible cases, anterior decompression via a transoral or endonasal approach may be necessary. In this operative video, we demonstrate an endoscopic endonasal transclival approach for odontoidectomy to successfully treat a 37-year-old female with severe basilar invagination causing symptomatic compression on the cervicomedullary junction resulting in unsteady gait and motor weakness. The patient had Klippel–Feil syndrome where the C1 arch was assimilated to the foramen magnum and transclival drilling was needed to adequately access the odontoid process for removal. A second-stage posterior occipitocervical stabilization and fusion was performed the following day. Immediate postoperative imaging showed excellent decompression of the cervicomedullary junction. Postoperatively, the patient had significant improvement in gait and motor strength in all extremities, and was ambulating independently without assistance at 1 year after surgery. The endoscopic endonasal transclival odontoidectomy is a useful strategy to treat severe irreducible basilar invagination causing symptomatic neural compression. The surgical technique and nuances are described in a step-by-step fashion in this illustrative operative video.The link to the video can be found at: https://youtu.be/HL4K7KqJEJM.

The management of clival chordomas: an Italian multicentric study.

In the last 2 decades, the endoscopic endonasal approach in the treatment of clival chordomas has evolved to be a viable strategy to achieve maximal safe resection of this tumor. Here, the authors present a multicentric national study, intending to analyze the evolution of this approach over a 20-year time frame and its contribution in the treatment of clival chordomas. Clival chordoma cases surgically treated between 1999 and 2018 at 10 Italian neurosurgical departments were included in this retrospective study. Clinical, radiological, and surgical findings, adjuvant therapy, and outcomes were evaluated and compared according to classification in the treatment eras from 1999 to 2008 and from 2009 to 2018. One hundred eighty-two surgical procedures were reviewed, with an increase in case load since 2009. The endoscopic endonasal transclival approach (EETA) was performed in 151 of 182 cases (83.0%) and other approaches were performed in 31 cases (17%). There was an increment in the use of EETA, neuronavigation, and Doppler ultrasound after 2008. The overall postoperative complication rate was 14.3% (26 of 182 cases) consisting of 9 CSF leaks (4.9%), 7 intracranial hemorrhages (3.8%), 5 cases of meningitis (2.7%), and 5 cerebral ischemic injuries (2.7%). Gross-total resection (GTR) was achieved in 93 of 182 cases (51.1%). Extent of resection (EOR) improved in the second era of the study. Signs and/or symptoms at presentation worsened in 27 cases (14.8%), and the Katz Index worsened in 10 cases (5.5%). Previous treatment, dural involvement, EETA, and intraoperative Doppler ultrasound correlated with GTR. Patients received adjuvant proton beam radiation in 115 of 182 cases (63.2%), which was administered more in the latter era. Five-year progression-free survival (PFS) and overall survival (OS) were 62.3% and 73.5%, respectively. GTR, EETA, proton beam therapy, and the chondroid subtype correlated with a better survival rate. The mean follow-up was 62 months. Through multicentric data collection, this study encompasses the largest series in the literature of clival chordomas surgically treated through an EETA. An increase in the use of this approach was found among Italian neurosurgical departments together with an improved extent of resection over time. The satisfactory rate of GTR was marked by low surgical morbidity and the preservation of patient quality of life. Surgical outcome was reinforced, in terms of PFS and OS, by the use of proton beam therapy, which was increasingly performed along the period of study.

Endoscopic transsphenoidal drainage of a petrous apex cholesterol granuloma using a frontal sinus nasal stent: a case report with long term follow up

Background Cholesterol granulomas of the petrous apex are benign cysts affecting 0.6 patients per 1 million. The pathophysiology involves cholesterol crystals and lipids that are surrounded by giant cells. The cholesterol deposits induce an inflammatory response likely from acute hemorrhage leading to the formation of a fibrous capsule. The capsule expands over time compressing nearby cranial nerves (VI–VIII), which can cause worsening symptoms. Surgical resection has been shown to provide excellent improvement in symptoms. Historically, open approaches such as the infracochlear, infralabyrinthine, and middle fossa have been used. Herein we present a case showing the feasibility and clinical utility of using an endoscopic endonasal transclival approach for treatment of these tumors. Case A 44-year-old female presented with history of intermittent double vision, dizziness, nausea, and headaches for 3 years. She developed a partial left CN6 palsy with significant diplopia and episodes of left facial weakness. The worsening symptoms prompted presentation to the ED where MRI and CT scan revealed a left petrous apex lesion (1.8 × 1.7 cm) with hyperintensity on T1 and T2 imaging, suggestive of cholesterol granuloma. She underwent an endoscopic transclival resection of the lesion: drainage of left petrous apex cholesterol granuloma and stent placement from left petrous apex into sphenoid sinus (novel technique). This was done to allow continued communication and drainage of the tumor bed from the petrous apex into the sphenoid sinus with the intent to minimize the risk of recurrence. At the postop visit both 6th nerve palsy and diplopia had resolved. Imaging is stable 2 years after the surgery. Discussion The placement of the stent in this case was done to prevent symptom recurrence. 11% of patients that do not receive a stent will have symptom recurrence within one year. From the historical literature, only 4% of patients who had stent placement developed cyst recurrence or expansion on follow-up imaging. Stent placement has been shown to prevent cyst enlargement within the first few months after surgery. We demonstrate that the endoscopic endonasal transclival approach provided good visualization of the tumor, allowed for an adequate working window for resection, and provided a sufficient approach for stent placement.

Sellar trough technique for endoscopic endonasal transclival repair

Background: Endoscopic endonasal transclival approaches provide direct access to the ventral skull base allowing the treating of clival and paraclival pathology without the manipulation of the brain or neurovascular structures. Postoperative spinal fluid leak, however, remains a challenge and various techniques have been described to reconstruct the operative defect. The “gasket seal” has been well-described, but has anatomic challenges when applied to clival defects. We describe a modification of this technique for use in endonasal transclival approaches.Methods: Two patients who underwent an endoscopic endonasal transclival approach for tumor resection with an intraoperative spinal fluid leak underwent a modified “gasket seal” closure technique for skull base reconstruction.Results: A 71-year-old woman with a petroclival meningioma and a 22 year old with a clival chordoma underwent endoscopic endonasal transclival resection with the modified repair. No new postoperative deficits occurred and no postoperative spinal fluid leak was seen with a follow-up of 17 and 23 months, respectively.Conclusion: We describe the successful use of a simple, low risk, and technique modification of the “gasket seal” technique adapted to the clivus that allows for hard reconstruction and facilitates placement of the nasoseptal flap.

Endoscopic endonasal resection of a clival chordoma with massive brainstem compression.

Chordomas are rare tumors that occur at an incidence rate of 0.8 per 100,000. Thirty-five percent of chordomas occur in the spheno-occipital region. We present a case of a clival chordoma that had severe brainstem compression. The patient had a 1-year history of slurred speech and left facial weakness (House-Brackmann 3). The endoscopic endonasal transclival approach gave a panoramic view of the region without the necessity of brain retraction or manipulation of the surrounding cranial nerves. Gross-total resection was achieved and no CSF leak was encountered postoperatively. The left facial weakness improved to House-Brackmann 1.The video can be found here: https://youtu.be/DzW9Q6ckTHw.

Endoscopic endonasal transclival approach to the ventral brainstem: Radiologic, anatomic feasibility and nuances, surgical limitations and future directions

The endoscopic endonasal transclival approach (EETA) is less invasive than traditional open approaches; however, there is currently limited data on the pre-operative features that may predict success of the EETA. Surgical landmarks and exposure of the EETA and expanded EETA are assessed. We retrospectively measured multiple anatomic features in 154 adult dry skulls, 22 C1 and C2 dry bone vertebrae, and 500 paranasal sinus computed tomography (CT) scans. We also dissected 13 formalin-fixed, silicone-injected adult cadaveric heads. Relevant qualitative and quantitative data were obtained with CT (n = 10) and cadaveric dissection (n = 13). They are expressed as mean (SD), as appropriate and compared with unpaired t tests. Categorical variables were compared with χ2 tests. We determined the prevalence of clival and sphenoid sinus anatomic variations and assessed potential exposure of the craniovertebral region, based on the relative position of the nasal bone tip, posterior point of the hard palate, and their relation to the position of C1 and C2. Depending on anatomic features, EETA should allow visualization of the ventral brainstem. The mean (SD) dimensions of the surgical window for EETA were 43.2 (5.1) × 18.3 (1.1) mm, in the craniocaudad and horizontal dimensions, respectively. The craniocaudad dimension enlarged to 60.2 (4.7) mm with expanded EETA. The EETA allowed satisfactory exposure for odontoid and C1 anterior arch resection (expanded EETA) in all specimens, regardless of the orientation of the palate. The combination of preoperative radiographic assessment and intraoperative considerations allows safe and effective application and facilitate selection of the most appropriate approach.

Anatomical Assessment of the Endoscopic Assisted Lateral Supraorbital Approach and Endoscopic Endonasal Transclival Approach to Basilar Apex Aneurysms.

To assess the feasibility of using an endoscopic-assisted lateral supraorbital (LSO) approach and an endoscopic endonasal transclival approach (EETA) for basilar apex (BAX) aneurysms. Ten cases with LSO approaches, with or without posterior clinoidectomy and endoscopic assistance, and 10 cases with EETA, with or without drilling of the dorsum sellae, were performed on 20 cadaveric heads. Anatomical exposure and surgical freedom at the BAX were evaluated. Anatomical exposure provided by the LSO approach was limited to the BAX and ipsilateral posterior cerebral artery (PCA) and increased with a mean value of 5.0 mm after posterior clinoidectomy; the basilar artery, contralateral PCA, and superior cerebellar arteries (SCAs) were visualized in all cases. Accordingly, surgical freedom was larger. Endoscopic assistance provided a significant increase in basilar artery exposure; however, surgical freedom did not increase markedly. The main advantage of EETA was the greatest exposure of the basilar artery. With drilling of the dorsum sellae, anatomical exposure increased by a mean value of 3.4 mm, and provided the greatest amount of surgical freedom and visualization of the basilar artery terminal bifurcation and of the SCAs in all cases. The endoscopic-assisted LSO approach and the EETA may represent a feasible approach for treatment of BAX aneurysms lying within 5.0 mm below and within 3.4 mm above the dorsum sellae.

Transclival clipping for giant vertebral artery aneurysm: A case report

Abstract Background Endovascular treatment often achieves complete obliteration of VA giant aneurysm; however, retreatment may be required because of late recanalization. We report a case of giant VA aneurysm that showed regrowth after endovascular treatment and was treated with VA clipping using the endoscopic endonasal transclival approach. Case description A 47-year-old man with chief complaint of ataxia underwent endovascular treatment of giant VA aneurysm. One year later, he needed additional treatment to regrowth of the aneurysm. We were not able to accomplish aneurysmectomy via the transcondylar fossa approach because of difficulty in achieving hemostasis and ended with partial thrombectomy. Digital subtraction angiography (DSA) performed after 4 months revealed coil compaction and distal flow due to recanalization. Right VA elongation and position of anterior spinal artery (ASA), these factors made possible for us to perform transclival approach to VA. Despite the limited indications for its use, endonasal endoscopic transclival clipping may be effective in limited anatomical cases. Conclusion We report the use of endonasal endoscopic transclival clipping for giant VA aneurysm. This endonasal endoscopic treatment may be an optional alternative in only limited cases depending upon the anatomical location of the lesion because of limitations of vascular control and the inability to visualize the field in the presence of major bleeding. For treatment of progressive giant VA aneurysm, it is very important to avoid optimistic strategy for giant VA aneurysm initially.

Endoscopic endonasal transclival approach for resection of a pontine cavernous malformation.

Symptomatic cavernous malformations in the ventral region of the pons are difficult to access surgically. The authors present a case of 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.The video can be found here: https://youtu.be/ePgpyij2Wpo.

Supratotal Resection of Residual Clival Chordoma With Combined Endoscopic Endonasal and Contralateral Transmaxillary Approaches: 2-Dimensional Operative Video.

The optimal treatment for skull base chordomas is gross total resection followed by radiotherapy and not radiation of partially resected tumors. Supratotal resection, defined as removal beyond all involved bone and dura, is ideal but difficult to achieve.  In this video, we present the case of a 37-yr-old man with new onset of progressive cranial nerve sixth palsy and a skull base lesion compatible with clival chordoma. He underwent partial surgical resection at an outside institution via transcranial approach, with significant tumor residual at the clivus, dorsum sella, posterior clinoids, and petrous apex, extensive dural invasion, and intradural extension with attachment to the basilar artery and its long perforating branches.  Supratotal surgical resection was achieved using an endoscopic endonasal transclival approach, ipsilateral transpteryoid approach to the foramen lacerum for carotid artery mobilization, bilateral interdural transcavernous approach with posterior clinoidectomies, and con-tralateral transmaxillary approach to the petrous apex. Reconstruction was performed in a multilayer fashion with fascia lata and fat grafts, extended nasoseptal flap, a lumbar drainage for 3 d. No cerebrospinal fluid leak occurred, and the abducens nerve palsy significantly improved at 3-mo follow-up. Proton therapy is planned.  Recent advances in endoscopic endonasal surgery allow for very high rates of complete and even supratotal resection despite the challenging location. A long learning curve to acquire the technical skills and complex surgical anatomy is required to decrease complication rates and achieve maximal resection in chordomas. Reoperations are more challenging and risky; therefore, first attempt should have curative intent.  The patient signed informed consent including the use of photographic and video material for educational or academic purposes.

Endoscopic Endonasal Transclival Approach to the Ventral Brainstem: Anatomic Study of the Safe Entry Zones Combining Fiber Dissection Technique with 7 Tesla Magnetic Resonance Guided Neuronavigation.

Treatment of intrinsic lesions of the ventral brainstem is a surgical challenge that requires complex skull base antero- and posterolateral approaches. More recently, endoscopic endonasal transclival approach (EETA) has been reported in the treatment of selected ventral brainstem lesions. In this study we explored the endoscopic ventral brainstem anatomy with the aim to describe the degree of exposure of the ventral safe entry zones. In addition, we used a newly developed method combining traditional white matter dissection with high-resolution 7T magnetic resonance imaging (MRI) of the same specimen coregistered using a neuronavigation system. Eight fresh-frozen latex-injected cadaver heads underwent EETA. Additional 8 formalin-fixed brainstems were dissected using Klingler technique guided by ultra-high resolution MRI. The EETA allows a wide exposure of different safe entry zones located on the ventral brainstem: the exposure of perioculomotor zone requires pituitary transposition and can be hindered by superior cerebellar artery. The peritrigeminal zone was barely visible and its exposure required an extradural anterior petrosectomy. The anterolateral sulcus of the medulla was visible in most of specimens, although its close relationship with the corticospinal tract makes it suboptimal as an entry point for intrinsic lesions. In all cases, the use of 7T-MRI allowed the identification of tiny fiber bundles, improving the quality of the dissection. Exposure of the ventral brainstem with EETA requires mastering surgical maneuvers, including pituitary transposition and extradural petrosectomy. The correlation of fiber dissection with 7T-MRI neuronavigation significantly improves the understanding of the brainstem anatomy.

Endoscopic endonasal transclival removal of tumors of the clivus and anterior region of the posterior cranial fossa (results of surgical treatment of 140 patients)

BackgroundUntil recently, tumors of the clivus and the anterior region of the posterior cranial fossa were considered extremely difficult to access and often inoperable using standard transcranial approaches. With the introduction into the neurosurgical practice of minimally invasive methods utilizing endoscopic techniques, it became possible to effectively remove hard-to-reach tumors, including central tumors of the anterior region of the posterior cranial fossa.MethodsFrom 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).ResultsUpper, 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 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%).ConclusionThe 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 fora 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.