Leo F. Ditzel Filho

Endonasal Endoscopic Approaches to the Paramedian Skull Base

OBJECTIVE To describe the technical and anatomic nuances related to endoscopic endonasal approaches (EEAs) to the paramedian skull base. METHODS Surgical indications, limitations, and technical aspects pertaining to EEAs designed to access areas oriented in the coronal plane are systematically reviewed with special attention to caveats, pitfalls, and common complications and how to avoid them. Case examples are presented. RESULTS The paramedian skull base may be divided into anterior (corresponding to the orbit and its contents), middle (corresponding to the middle cranial, pterygopalatine, and infratemporal fossae), and posterior (includes the craniovertebral junction lateral to the occipital condyles and the jugular foramen) segments. EEAs to the anterior segment offer access to the intraconal orbital space and the optic canal. A transpterygoid corridor typically precedes EEAs to the middle and posterior paramedian approaches. EEAs to the middle segment provide wide exposure of the petrous apex, middle cranial fossa (including cavernous sinus and Meckel cave), and infratemporal and pterygopalatine fossae. Finally, EEAs to the posterior segment access the hypoglossal canal, occipital condyle, and jugular foramen. CONCLUSIONS Approaches to the paramedian skull base are the most challenging and complex of all endoscopic endonasal techniques. Because of their technical complexity, it is recommended that surgeons master endoscopic endonasal anatomic approaches oriented to median structures (sagittal plane) before approaching paramedian (coronal plane) pathologies.

Expanded Endonasal Approaches to Middle Cranial Fossa and Posterior Fossa Tumors

Skull base lesions that involve the middle and posterior cerebral fossae have been historically managed through extensive transcranial approaches. The development of endoscopic endonasal techniques during the past decade has made possible a vast array of alternative routes to the ventral skull base, providing the ability to expose lesions in difficult-to-access regions of the cranial base in a less invasive manner. In this review, the authors detail the endoscopic surgical anatomy and the operative nuances of the expanded endoscopic endonasal approaches to tumors of the middle and posterior cranial fossae. These techniques offer excellent exposure of the targeted regions yielding optimal resections, while avoiding the morbidity associated with transcranial surgical approaches.

Endoscopic Endonasal Approach for Removal of Tuberculum Sellae Meningiomas

Tuberculum sellae meningiomas are challenging lesions; their critical location and often insidious growth rate enables significant distortion of the superjacent optic apparatus before the patient notices any visual impairment. This article describes the technical nuances, selection criteria and complication avoidance strategies for the endonasal resection of tuberculum sellae meningiomas. A stepwise description of the surgical technique is presented; indications, adjuvant technologies, pitfalls and the relevant anatomy are also reviewed. Tuberculum sellae meningiomas may be safely and effectively resected through the endonasal route; invasion of the optic canals does not represent a limitation.

Applications of transoral, transcervical, transnasal, and transpalatal corridors for Robotic surgery of the skull base

INTRODUCTION Endoscopic endonasal approaches (EEAs) provide an alternative surgical corridor to treat benign and malignant lesions of the sinonasal tract and skull base. According to the extent of the lesion and the surgical team experience, an endoscopic endonasal skull base approach can provide exposure of vital neurovascular structures and enable the surgeon to resect the lesion safely and completely. Similarly, robotic-assisted surgery facilitates the performance of highly complex surgeries in areas of the upper aerodigestive tract that are relatively difficult to access or to manipulate instruments, such as the oral cavity, nasopharynx, oropharynx or hypopharynx, supraglottis, glottis, parapharyngeal space and infratemporal fossa (ITF). Operative time and time of hospitalization are superior to those associated with open approaches and are associated with less morbidity. Various feasibility studies have suggested that robotic-assisted surgery may be applied to skull base surgery with similar results. In general, skull base surgery is difficult and complex due to its anatomical intricacies, deep-seated nature, and the presence of adjacent vital structures. In addition, the relative rarity of indications increases the difficulty for a surgeon to become familiar with the detailed anatomy and the various pathologies affecting the region. This study was undertaken to better define and understand the potential use and limitations of current robotic approaches to the skull base.

Comparative analysis of the anterior transpetrosal approach with the endoscopic endonasal approach to the petroclival region

OBJECTIVE The endoscopic endonasal approach (EEA) offers direct access to midline skull base lesions, and the anterior transpetrosal approach (ATPA) stands out as a method for granting entry into the upper and middle clival areas. This study evaluated the feasibility of performing EEA for tumors located in the petroclival region in comparison with ATPA. METHODS On 8 embalmed cadaver heads, EEA to the petroclival region was performed utilizing a 4-mm endoscope with either 0° or 30° lenses, and an ATPA was performed under microscopic visualization. A comparison was executed based on measurements of 5 heads (10 sides). Case illustrations were utilized to demonstrate the advantages and disadvantages of EEA and ATPA when dealing with petroclival conditions. RESULTS Extradurally, EEA allows direct access to the medial petrous apex, which is limited by the petrous and paraclival internal carotid artery (ICA) segments laterally. The ATPA offers direct access to the petrous apex, which is blocked by the petrous ICA and abducens nerve inferiorly. Intradurally, the EEA allows a direct view of the areas medial to the cisternal segment of cranial nerve VI with limited lateral exposure. ATPA offers excellent access to the cistern between cranial nerves III and VIII. The quantitative analysis demonstrated that the EEA corridor could be expanded laterally with an angled drill up to 1.8 times wider than the bone window between both paraclival ICA segments. CONCLUSIONS The midline, horizontal line of the petrous ICA segment, paraclival ICA segment, and the abducens nerve are the main landmarks used to decide which approach to the petroclival region to select. The EEA is superior to the ATPA for accessing lesions medial or caudal to the abducens nerve, such as chordomas, chondrosarcomas, and midclival meningiomas. The ATPA is superior to lesions located posterior and/or lateral to the paraclival ICA segment and lesions with extension to the middle fossa and/or infratemporal fossa. The EEA and ATPA are complementary and can be used independently or in combination with each other in order to approach complex petroclival lesions.

The Endoscopic Endonasal Approach for Removal of Petroclival Chondrosarcomas

Chondrosarcomas of the skull base are rare, locally invasive tumors that typically arise in the petroclival region, from degenerated chondroid cells located within the synchondrosis. Given their usually slow growth rate, they are capable of reaching sizable dimensions, promoting bone erosion and significant displacement of neurovascular structures before causing symptomatology that will eventually lead to diagnosis; cranial neuropathies and headaches are common complaints. This article discusses the pertinent surgical anatomy, patient selection criteria, technical nuances and complication management of the endonasal resection of skull base chondrosarcomas.

Effect of Incremental Endoscopic Maxillectomy on Surgical Exposure of the Pterygopalatine and Infratemporal Fossae

Objective Access to the pterygopalatine and infratemporal fossae presents a significant surgical challenge, owing to their deep-seated location and complex neurovascular anatomy. This study elucidates the benefits of incremental medial maxillectomies to access this region. We compared access to the medial aspect of the infratemporal fossa provided by medial maxillectomy, anteriorly extended medial maxillectomy, endoscopic Denker approach (i.e., Sturmann-Canfield approach), contralateral transseptal approach, and the sublabial anterior maxillotomy (SAM). Methods We studied 10 cadaveric specimens (20 sides) dissecting the pterygopalatine and infratemporal fossae bilaterally. Radius of access was calculated using a navigation probe aligned with the endoscopic line of sight. Area of exposure was calculated as the area removed from the posterior wall of maxillary sinus. Surgical freedom was calculated by computing the working area at the proximal end of the instrument with the distal end fixed at a target. Results The endoscopic Denker approach offered a superior area of exposure (8.46 ± 1.56 cm(2)) and superior surgical freedom. Degree of lateral access with the SAM approach was similar to that of the Denker. Conclusion Our study suggests that an anterior extension of the medial maxillectomy or a cross-court approach increases both the area of exposure and surgical freedom. Further increases can be seen upon progression to a Denker approach.

Extracapsular dissection technique with the Cotton Swab for pituitary adenomas through an endoscopic endonasal approach – How I do it

BackgroundPituitary adenomas are often encased in a histological pseudocapsule that separates the tumor from the normal gland. Transsphenoidal adenoma resection may be performed either in an intra- or an extracapsular technique. The extracapsular fashion offers anatomical orientation, removal of a security margin, reduced risk of opening the arachnoid layer with subsequent CSF flow and identification of invasion.MethodThe sella turcica is approached through the classic endoscopic endonasal route. After opening the dura of the sellar floor, the interface between the compressed tissue and the normal gland is used as a surgical plane for dissection. Performing slight counter-traction with the suction tube, the cleavage plane is identified and stepwise unsealed in an atraumatic fashion with the cotton swab. Once the cleavage plane is partially loosened, repeated twisting movements are performed with the cotton swab to enucleate the pseudocapsule and adenoma.ConclusionBoth micro- and macroadenomas presenting a pseudocapsule may be resected in the extracapsular dissection technique with the cotton swab. Operating in an endoscopic three- to four hands technique enables to visualize the anatomic planes and perform twisting movements with the cotton swab separating pseudocapsule and tumor in order to enucleate the adenoma.

Endoscopic endonasal technique: treatment of paranasal and anterior skull base malignancies

UNLABELLED Technical and technological innovations have spearheaded the expansion of the indications for the use of endoscopic endonasal approaches to extirpate malignancies of the sinonasal tract and adjacent skull base. OBJECTIVE Critical review of the available literature regarding the use of endoscopic endonasal approaches including indications, limitations, surgical techniques, oncologic outcome, and quality of life. METHOD Various endoscopic endonasal techniques are reviewed according to the origin and local extension of sinonasal and skull base malignancies including anterior cranial base, nasopharynx, clivus, and infratemporal fossa. In addition, the available literature is reviewed to assess outcomes. CONCLUSION Endoscopic endonasal approaches are an integral part of the armamentarium for the treatment of the sinonasal tract malignancies and skull base. In properly selected cases, it affords similar oncologic outcomes with lower morbidity than traditional open approaches. Nonetheless, these minimal access approaches should be considered a complement to well-established open approaches, which are still necessary in most advanced tumors.

Surgical management of craniopharyngioma with third ventricle involvement

Craniopharyngiomas are notorious for their ability to invade the hypothalamus and third ventricle. Although several transcranial approaches have been proposed for their treatment, the endonasal route provides direct access to the tumor with no need for cerebral retraction or manipulation of the optic apparatus. After the lesion is debulked, the unique angle of approach achieved with this technique enables the surgeon to perform an extra-capsular dissection and visualize the walls of the third ventricle, the foramina of Monro, and the anterior comissure. Moreover, the enhanced magnification and lighting afforded by the endoscope facilitate safe tumor removal, particularly in areas where there is loss of clear lesion delimitation and greater infiltration of the surrounding structures. Herein we present the case of a 68-year-old female patient with a 3-month history of visual deterioration accompanied by worsening headaches. Investigation with magnetic resonance imaging revealed a heterogeneous mass in the suprasellar region, extending into the third ventricle and displacing the pituitary gland and stalk inferiorly. Hormonal profile was within expected range for her age. An endonasal, fully endoscopic, transplanum transtuberculum approach was performed. Gross-total removal was achieved and pathology confirmed the diagnosis of craniopharyngioma. Postoperative recovery was marked by transient diabetes insipidus. Closure was achieved with a pedicled nasoseptal flap; despite exploration of the third ventricle, there was no cerebrospinal fluid leakage. Pituitary function was preserved. Visual function has fully recovered and the patient has been uneventfully followed since surgery. The video can be found here: http://youtu.be/it5mpofZl0Q. (http://thejns.org/doi/abs/10.3171/2013.V1.FOCUS12330)