Techniques and challenges of the expanded endoscopic endonasal sellar and parasellar approaches to invasive pituitary tumors.

BACKGROUND: Superb knowledge of surgical anatomy and nuances to remove the natural barriers preventing full access to the paramedian skull base determines the ease of using the expanded sellar/parasellar approaches as the main gateway for all the parasagittal modules during endoscopic endonasal access (EEA) to pituitary tumors with cavernous sinus (CS) invasion. METHODS: Throughout stepwise-cadaveric dissections and pertinent intraoperative analysis, we describe surgical pearls and pitfalls of the parasellar-EEA with special references to the utility of various lines/classifications on neuroimaging correlated with strategies to enhance surgical safety and tumor resection. CONCLUSION: EEA to invasive parasellar pathologies needs to address strict bleeding control and displacement of neurovascular structures inside the CS, posing a chance for neurologic morbidities/ICA injury. Meticulous utilization of operative landmarks and strategies can help avoid and mitigate surgical complications.

Bony landmarks in the endoscopic endonasal transoculomotor approach.

The endoscopic endonasal transoculomotor approach (EETA) has been recently described as a doorway to access the parapeduncular space and treat pituitary adenomas with oculomotor extension. Intraoperative identification of the oculomotor triangle endonasally is challenging and dissection can put the internal carotid artery (ICA) at risk. The aim of the present study is to find reliable landmarks that identify the oculomotor triangle (OCMT) during the EETA and protect the ICA from injury. Several lines were defined for calculations. Among them, one oblique line that extends from the inferior margin of the lateral orbital canal recess to the vidian canal was named the clinoid-to-vidian line (CVL), while a vertical line that extends over the most medial point of the paraclival ICA was titled the sagittal paraclival line (SPL). Anatomic relationships between the OCMT to these lines were assessed in 7 cadaveric heads. The intersecting point between the CVL and SPL is located within 2 mm of the center of the OCMT (mean 0.8 ± 0.5 mm), and 1.1 ± 0.8 mm medially and above the parasellar ICA. CVL and SPL are reliable landmarks during the EETA that can both protect the parasellar ICA and anatomically orientate to the blind spot that corresponds with the OCMT. We recommend starting dissection medial and superior to the CVL-SPL intersecting point, and carry the dissection laterally thereafter to avoid inadvertent injury of the ICA.

Endoscopic approaches to skull base malignancies affecting the anterior fossa.

Anterior skull base malignancies are rare and comprise distinct histological entities. Surgery encompasses the traditional craniofacial resections (CFR), and more recently, endoscopic endonasal approaches (EEA) or a hybrid cranioendoscopic (CEA) technique. Although the CFR is still considered the "gold-standard;" there is growing evidence supporting that EEA yield equivalent oncologic outcomes with less morbidity in well-selected cases. Therefore, this article aims to review the current state-of-art in addressing anterior cranial base malignancies using expanded endoscopic endonasal approaches (EEA) with particular references to surgical anatomy and nuances of hybrid cranioendoscopic techniques. Cadaveric dissections and illustrative cases are presented to detail our current surgical technique allied with tailored adjuvant therapies, and treatment strategies are further discussed based on tumor histology.

Safety and effectiveness of endoscopic endonasal intracranial aneurysm clipping: a systematic review.

Once considered far-fetched, endoscopic endonasal clipping (EEC) has been reported as a feasible alternative route for treating intracranial aneurysms located in the midline. Appropriately, debates regarding EEC applicability have arisen amongst the neurosurgical community. We aim to define the safety, effectiveness, and current state-of-art in the use of EEC for intracranial aneurysms. Two databases (PubMed, Cochrane) were queried for intracranial aneurysms that underwent EEC between inception and 2019. Literature review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Data regarding clinical presentation, radiological imaging, and outcome were extracted and analyzed from selected publications. Nine studies with 27 patients (8 males, 19 females), harboring 35 aneurysms (9 ruptured, 26 nonruptured), met the predetermined inclusion criteria. Patient age range is from 34 to 70 (median = 50) years old. Four aneurysms were considered not suitable for EEC during the procedure, and two aneurysms required additional treatment, leading to an overall treatment success (obliteration) rate of 86%. Complications occurred in 7 patients (26%), including CSF leakage in 5 patients (18%) and ischemic complications in 4 (15%). Among the cases reported, complications occurred more frequently in posterior circulation aneurysms in comparison with anterior circulation aneurysms (62.5 vs 10.5%). Ischemic complications occurred in 4 out of 8 posterior circulation aneurysms. Although feasible, EEC is associated with a significant risk of complications, with rates identified that are significantly higher than established open clipping or endovascular management. The current data suggest that transcranial clipping and endovascular occlusion are still the primary indication for treating intracranial aneurysms.

The historical perspective in approaches to the spheno-petro-clival meningiomas.

The current literature regarding surgical treatment for tumors in the sphenopetroclival (SPC) region is merely scarce. Through a comprehensive literature review, we investigated the indications, outcomes, and complications of different surgical approaches to the SPC meningiomas. Given its complicated relationship between these slow-progression tumors and some critical neurovascular structures in the SPC region, surgical treatment of these tumors faces the challenge of achieving a maximal grade of resection, while preserving patient functionality. The development of new surgical techniques and approaches in recent years have permitted the advancement in the treatment of these tumors, with acceptable rates of morbidity and mortality. The choice of a surgical approach as a treatment for the lesion depends mainly on the type of tumor extension, surgeon's preferences, and the displacement of neurovascular structures. Rather than focusing on one single strategy of treatment, the skull-base surgeon should tailor the approach based on the origin and features of the lesion; as well as the peculiarities of the surgical anatomy. This strategy aims to decrease morbidity and to optimize tumor resection and patient quality of life.

Surgical anatomy and nuances of the expanded endonasal transdorsum sellae and posterior clinoidectomy approach to the interpeduncular and prepontine cisterns: a stepwise cadaveric dissection of various pituitary gland transpositions.

BACKGROUND: Excelsior knowledge of endoscopic anatomy and techniques to remove the natural barriers preventing full endonasal access to the interpeduncular and prepontine cisterns determines the ease of transposing the pituitary gland (hypophysiopexy) preserving the glandular function without manipulating the optic apparatus and the oculomotor nerves. METHODS: Throughout stepwise cadaveric dissections, we describe the expanded endonasal approach (EEA) to the interpeduncular and prepontine cisterns with special references to the intricate anatomy of the region and techniques for hypophysiopexy and posterior clinoidectomies. CONCLUSION: This article illustrates sellar-diaphragmatic dural incisions and various "pituitary gland transpositions" techniques performed via extradural (lifting the gland still covered by both dural layers), interdural (transcavernous), and intradural (between the medial wall of the cavernous sinus and the pituitary tunica) to access the prepontine and interpeduncular cisterns.

Surgical anatomy and nuances of the expanded transpterygoid approach to the pterygopalatine fossa and upper parapharyngeal space: a stepwise cadaveric dissection.

BACKGROUND: Superb knowledge of anatomy and techniques to remove the natural barriers preventing full access to the most lateral aspect of the skull base determines the ease of using the transpterygoid approach (ETPA) as the main gateway for all the coronal planes during endonasal surgeries. METHODS: Throughout stepwise image-guided cadaveric dissections, we describe the surgical anatomy and nuances of the ETPA to the pterygopalatine fossa (PPF) and upper parapharyngeal space (UPPS). CONCLUSION: The ETPA represents a lateral extension of the midline corridor and provides a valuable route to access the PPF/UPPS. Major landmarks for this EEA are the infraorbital canal, sphenopalatine foramen, and vidian nerve. It comprises the removal of the palatine bone, posterior wall of the maxillary sinus, and PPF transposition to drill the pterygoid process.

Surgical anatomy and nuances of the extended endoscopic endonasal transtuberculum sellae approach: pearls and pitfalls for complications avoidance.

BACKGROUND: Using the expanded endoscopic transtuberculum approach (EETA), the nuances of this technique have rendered a safe, direct, and feasible ventral corridor for the treatment of extending suprasellar pathologies. This study illustrates surgical landmarks and strategies of paramount importance for complications avoidance. METHODS: This study presents the surgical anatomy and nuances of EETA, which can be used to remove large pituitary adenomas with suprasellar extension. Special references to cadaveric dissections highlight anatomical landmarks and surgical key points for complications avoidance. CONCLUSION: The EETA represents a versatile route for the treatment of sellar/suprasellar pathologies. Although, sizeable extrasellar pituitary tumors still pose a threat due to displacement/encasement of surrounding structures, necessitating accurate knowledge of correlative operative anatomy with traditional landmarks. Complete resection of extrasellar components is essential to avoid postoperative apoplexy.

Endoscopic Endonasal Approach for Clival Chordoma with Subarachnoid Invasion: A Two-Dimensional Step-by-Step Operative Video.

Chordomas are slow-growing, low-grade, locally invasive, and locally aggressive tumors. They peak at 40-60 years of age, with a male preponderance (2:1). Belonging to the sarcoma family and thought to develop from the notochord remnant, they are most commonly found in the midline, with half located at the sacrum and about one third at the skull base.1 Their treatment mainly consists of surgical excision, followed by radiation therapy.2 The endoscopic endonasal approach provides direct access to the clival chordomas with no need for brain retraction or manipulation of neurovascular structures.3-5 Herein we present a step-by-step resection technique of a clival chordoma invading the subarachnoid space and touching the brainstem and vertebrobasilar vessels in a 46-year-old man with headaches, with a prior failed attempt of resection at an outside institution, resulting in a biopsy only in the palate. An endoscopic endonasal transclival approach was performed and gross total removal was achieved (Video 1). The patient had an uneventful recovery with no deficits, and he was then sent to proton beam therapy.

Expanded endoscopic endonasal approach for extending suprasellar and third ventricular lesions.

BACKGROUND: Expanded endonasal approaches can provide direct access to the midline skull base from the anterior cranial fossa to the ventral foramen magnum. Surgical strategies of bone drilling, dural opening, and intradural dissection can determine the area of surgical exposure and instrument handling, affecting the safety of devascularizing/debulking suprasellar tumors. METHODS: We describe an expanded endoscopic endonasal approach for suprasellar lesions, with stepwise image-guided dissections highlighting surgical pearls and pitfalls to enhance surgical safety. This article presents transnasal intra-third-ventricular anatomy from trans-tuber cinereum, and trans-lamina terminalis approaches, comparing subchiasmatic and suprachiasmatic trajectories. CONCLUSION: The rostral extension via endoscopic endonasal transsellar-transtubercular-transplanum approaches can provide a safe and feasible route for suprasellar lesions, in subchiasmatic, suprachiasmatic, and intraventricular regions.

Focused endoscopic endonasal craniocervical junction approach for resection of retro-odontoid lesions: surgical techniques and nuances.

BACKGROUND: Lesions posterior to the odontoid process pose a surgical challenge. Posterolateral approaches to this region are considerably risky for the spinal cord. Transoral approaches are limited in terms of exposure and can also carry morbidity. METHODS: We describe a focused endoscopic endonasal approach (EEA) for removing an osteochondroma located dorsal to the odontoid process. The surgical pearls and pitfalls using stepwise image-guided EEA cadaveric dissections are highlighted defining the importance of various craniocervical junction (CCJ) lines on imaging. CONCLUSION: EEA to CCJ can be offered, with lower morbidity than other approaches, even for lesions that extend posterior and caudal to the odontoid process. Radiologic predictors of exposure and intraoperative techniques to enhance endoscopic visualization are discussed.

Salvage Free Tissue Transfer for Clival Osteoradionecrosis After Repeat Proton Beam Therapy.

BACKGROUND: Craniocervical junction chordoma treated with surgery and Proton Beam Therapy evolved with Osteonecrosis and CSF leak. As the vascularization of the head was compromised, we harvested an Anterolateral thigh musculofascial flap to seal the leak. CASE DESCRIPTION: A 56-year-old man presented with a history of chronic headaches and dysarthria with tongue deviation to the right. Magnetic resonance imaging showed a lesion at the craniocervical junction with imaging characteristics compatible with chordoma. Endoscopic endonasal resection was followed by proton beam therapy. Recurrence of the chordoma was subsequently resected via far lateral approach again followed by proton beam therapy accumulating a total dose of 75 Gy. Unfortunately, this led to osteoradionecrosis of the skull base resulting in a cerebrospinal fluid (CSF) leak more than 1 year after treatment. After multiple failed attempts to seal the defect using local vascularized tissue and free fat grafts, the defect was reconstructed with a vastus lateralis free tissue transfer. Six weeks later, the flap had mucosalized, the patient was pain free, and there was no evidence of a CSF leak. CONCLUSIONS: In select cases, vascularized free flaps offer a superior reconstruction for osteoradionecrosis because radiotherapy often compromises the blood supply of local tissues.

Surgical nuances of the expanded endoscopic anterior skull base craniectomy for hyperostotic meningioma resection.

BACKGROUND: The rostral expanded endoscopic approach (EEA) to anterior cranial fossa (ACF) has several advantages over transcranial/craniofacial surgery, providing early access to the vascular supply of tumors and reducing morbidities of craniotomy especially that of brain retraction. This article presents endoscopic landmarks and nuances for a wide ACF corridor, with stepwise image-guided dissections highlighting surgical tricks and techniques to enhance surgical safety. METHODS: We describe an expanded endoscopic endonasal anterior skull base craniectomy for a recurrent large olfactory groove hyperostotic meningioma, with correlated cadaveric dissections. CONCLUSION: The widening of rostral EEA can provide a safe and feasible route to access ACF. This article highlights the specific landmarks in endoscopic anatomy with reference to the angle of visualization and bayonetted instruments.

Techniques and challenges of the expanded endoscopic endonasal access to the ventrolateral skull base during the "far-medial" and "extreme medial" approaches.

BACKGROUND: Expanding the ventrolateral skull base corridor from the midline of lower clivus to the petroclival fissure is a challenging endonasal surgical task. Resection of lytic lesions like chondrosarcoma can cause cranial nerve morbidities and injury of ICA, necessitating accurate knowledge of correlative endoscopic anatomy with stereotactic landmarks. METHODS: We describe an extended endoscopic endonasal approach (EEA) for a right petroclival chondrosarcoma with the demonstration of ipsilateral surgical landmarks with contralateral normal correlates, using a stepwise comparative image-guided cadaveric dissection study. CONCLUSION: EEA for lytic lesions like chondrosarcomas needs to address brain shift and displacement of ICA, posing a chance for cranial nerve morbidities and ICA injury. Meticulous utilization of intraoperative stereotactic landmarks can help avoid and mitigate surgical complications.

The importance of landmarks in endoscopic endonasal reinterventions: the transpterygoid transcavernous approach.

BACKGROUND: Sellar and parasellar regions are anatomically complex region and in close relationship with important neurovascular structures. Hence, surgical treatment of recurrent aggressive pituitary adenomas invading the cavernous sinus represents an operative challenge, given the lack of landmarks that are missed because of the scar tissue and previous interventions. METHODS: We describe in detail the surgical technique of the transpterygoid transcavernous approach (TPTCa) for the surgical re-operation of a recurrent pituitary adenoma invading the left cavernous sinus in the context of a Nelson syndrome after bilateral adrenalectomy. We highlight the main anatomical key elements involved in this approach as well as the technical aspects for avoiding surgical complications. CONCLUSION: The TPTCa is a versatile approach that uses the endoscopic transsphenoidal route and thereby, avoids brain retraction. Anatomic landmarks offer a good sense of the area that is exposed in reoperations and reduce the risk of injury of important neurovascular structures located within the cavernous sinus and the parasellar region.

Expanded endoscopic endonasal transpterygoid transmaxillary approach for a giant trigeminal schwannoma.

Atypical trigeminal schwannomas (ATSs) are notorious for their ability to invade the skull base. An expanded endoscopic endonasal approach (eEEA) provides direct access to the tumor with no need for cerebral retraction or manipulation of neurovascular structures. Herein, we present a case of a large temporal fossa extradural lesion with secondary invasion of the sella, clivus, and temporal and infratemporal fossae in a 49-year-old male with severe vision loss. A transpterygoid transmaxillary approach was performed. Gross-total removal was achieved and pathology revealed the diagnosis of ATS. Visual function fully recovered in the right side and the patient has been uneventfully followed since surgery. The video can be found here: https://youtu.be/6pSwdYsN9hk.

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.