Transantral endoscopic approach for the treatment of lesions affecting the maxillary nerve.

BACKGROUND: Surgical approaches to skull base lesions that affect the maxillary nerve are complex, due to deep location and presence of relevant neurovascular structures surrounding this area. METHOD: We propose the transantral endoscopic approach (TEA) for the treatment of lesions affecting the maxillary nerve or its vicinity. More specifically, the ones that are located anterior to the foramen rotundum. CONCLUSIONS: This technique represents a minimally invasive treatment option for these kind of cranial base lesions. It offers optimal visualisation similar to the endonasal approach, whereas less dissection is required.

Septal rhinopharyngeal flap: a novel technique for skull base reconstruction after endoscopic endonasal clivectomies.

Endoscopic endonasal reconstruction techniques have improved CSF leak rates that were initially reported after surgery for cranial base and intradural lesions. However, wide surgical defects still pose a problem, especially if located in the clival region. The authors propose and describe a novel reconstruction technique they call a septal rhinopharyngeal flap (SRF) specifically designed to address this issue. The SRF is formed by three components of mucosa: 1) septal, 2) rhinopharyngeal roof, and 3) rhinopharyngeal posterior wall components, which allows for the coverage of the tuberculum/sellar region, midclivus, and lower clivus, respectively. A step-by-step procedure is described and its results analyzed in cases in which it has been used. The SRF was performed in 8 patients, which included diagnoses of 4 chordomas, 2 petroclival meningiomas, 1 invasive pituitary adenoma, and 1 chondrosarcoma. The size of the flap was considered optimal in all patients (100%). Postoperative MRI revealed contrast enhancement covering the entire surface of the flap. No CSF leaks were encountered after at least 1 postoperative year. The SRF is a novel vascularized reconstruction technique specifically indicated for wide endosanasal clivectomies focused on the middle clivus with caudal extension into the lower clivus and craniocervical junction, as well as rostral extensions into the tubercular or planum sphenoidale. This new reconstruction technique could be added to the skull base reconstruction armamentarium as a safe and optimal option.

Spontaneous CSF rhinorrhea as a presenting symptom of a clival chordoma.

CSF rhinorrhea is a rare presenting symptom of a clival chordoma as these tumors do not tend to show dural invasion as a histological feature. Here we discuss the case of a 61 years old female with spontaneous rhinorrhea secondary to a clival chordoma, and the value of some specific MRI sequences in accurate identification of a tumor with such atypical presentation, enabling the surgeon to plan accordingly.

Impact of Multilayer Vascularized Reconstruction after Skull Base Endoscopic Endonasal Approaches.

Background The use of vascularized flap to reconstruct the skull base defects has dramatically changed the postoperative cerebrospinal fluid (CSF) leak rates allowing the expansion of endoscopic skull base procedures. At present, there is insufficient scientific evidence to permit identification of the optimal reconstruction technique after the endoscopic endonasal approach (EEA). Objective The main purpose of this article is to establish the risk factors for failure in the reconstruction after EEA and whether the use of a surgical reconstruction protocol can improve the surgical results. Material and Methods A retrospective cohort study was conducted in our institution, selecting patients that underwent EEA with intraoperative CSF leak. Two reconstructive protocols were defined based on different reconstructive techniques; both were vascularized but one monolayer and the other multilayer. A multivariate analysis was performed with outcome variable presentation of postoperative leak. Results One hundred one patients were included in the study. Patients reconstructed with protocol 1, with the diagnosis different to the pituitary adenoma and older than 45 years old had higher risk of presenting postoperative leak, and with statistically significant differences when we adjusted for the remaining variables. Conclusion The vascularized reconstructions after endoscopic endonasal skull base approaches have demonstrated to be able to obtain a low rate of postoperative CSF leak. The multilayer vascularized technique may provide a more evolved technique, even reducing the postoperative leak rates comparing with the monolayer vascularized one. The reconstructive protocol employed in each case, as well as age and histological diagnosis, is independent risk factor for presenting postoperative leak.

An Anatomically-Based Endoscopic Endonasal Model to Navigate the Anterior Ventral Skull Base.

BACKGROUND: Endoscopic endonasal approaches to access the sellar and parasellar regions are challenging in the face of anatomical variations or pathologic conditions. We propose an anatomically-based model including the orbitosellar line (OSL), critical oblique foramen line (COFL), and paramedial anterior line (PAL) facilitating safe, superficial-to-deep dissection triangulating upon the medial opticocarotid recess. METHODS: Five cadaveric heads were dissected to systematically expose the OSL, COFL, and PAL, illustrated with image guidance. Application of the coordinate system and a 6-step dissection sequence is described. RESULTS: The coordinate system consists of 1) the OSL, connecting a) the anterior orbital point, junction of the anterior buttress of the middle turbinate with the agger nasi region, located 34.3 ± 0.9 mm above the intersection of the vertical plane of the lacrimal crest, and the orthogonal plane of the maxillo-ethmoidal suture; b) the posterior orbital point, junction of the optic canal with the lamina papyracea, located 4 ± 0.7 mm below the posterior ethmoidal artery; and c) the medial opticocarotid recess; 2) COFL (15 ± 2.8 mm), connecting the palatovaginal canal, vidian canal, and foramen rotundum; and 3) PAL (39 ± 0.06 mm), connecting the vidian canal with the posterior ethmoidal artery. CONCLUSIONS: OSL, COFL, and PAL form an anatomically-based model for the systematic exposure when accessing the parasellar and sellar regions. Preliminary anatomical data suggest that this model may be of value when normal anatomy is distorted by pathology or anatomic variations.

Radiological Study of the Carotid-Clival Window and Its Application in Endoscopic Endonasal Expanded Approaches.

BACKGROUND: The surgical approach to the petrous apex (PA) and petroclival junction (PCJ) remains a challenge. The carotid-clival window (CCW) represents the widest window available to approach the PCJ from a mediolateral endoscopic route. Here we define the CCW radiologically in nonpathological conditions, to establish the anatomic variability of the PCJ, relate this variability to pneumatization patterns, and evaluate some technical concerns conditioned by the CCW. METHODS: This was an analytical study of 10 multislice computed tomography scans from patients without SB pathology. Bilateral measures were taken at the roof and floor levels of the lacerum canal (LC) and its posterior projection over the PCJ (segments DE and QR). All measures were compared across different pneumatization patterns. RESULTS: The DE and QR lengths were found to be the most important measures affecting the width of the CCW. Wide variability was observed, with a mean DE length of 8.52 mm (range, 2.4-12.8 mm) at the LC floor level and a mean QR length of 9.11 mm (range, 4.3-13.1 mm) at the LC roof level. The presence of retrocarotid pneumatization was statistically significantly associated with longer DE and QR segments. No differences were found among other pneumatization patterns. CONCLUSIONS: The CCW varies widely among individuals. The presence of pneumatization behind the paraclival carotid represents an advantageous characteristic when planning an endoscopic approach to the PCJ.