Endoscopic Petrous Apex Surgery: The Utilization of Frontal Sinus Instrumentation.

BACKGROUND: The petrous apex is a complex anatomic region for which each surgical approach each has distinct limitations. The authors describe the use of frontal sinus instrumentation for the endonasal endoscopic approach to petrous apex lesions OBJECTIVE:: To demonstrate that the angled design of frontal sinus instrumentation has pronounced clinical utility for the transsphenoidal transclival approach to the petrous apex. METHODS: The authors present cases of expansile petrous apex lesions approached endoscopically via transsphenoid and transclival corridors, and highlight the technique of using curved frontal sinus instruments and angled endoscopes for posterolateral reach in the petrous apex dissection. RESULTS: As demonstrated in the accompanying video, dissection with frontal sinus instrumentation allows the surgeon to navigate around the internal carotid artery. CONCLUSIONS: Significant technical and technological advances have been made in the field of expanded endoscopic endonasal skull base surgery in the past 3 decades. Increasing efforts are made to push the boundaries and access more laterally located lesions, such as those in the petrous apex. Surgical trajectory or vector is paramount to safely navigate around the internal carotid artery.

Quantifying Lateral Frontal Sinus Access: The Upper Blepharoplasty Approach.

OBJECTIVE: Despite advances in technology and instrumentation, access to the lateral frontal sinus remains a challenge for surgeons. We sought to quantify the reach and applicability of the upper blepharoplasty approach (UBA) to the frontal sinus. METHODS: Twelve cadaveric specimens were obtained for anatomic research and frontal sinuses divided into 3 zones. Zone 1 was defined as medial to the supraorbital neurovascular bundle (SON). The remaining orbit was then bisected to define zone 2 (centrally) and zone 3 (laterally). Twenty-four UBAs were performed followed by 12 modified endoscopic Lothrop procedures (MELP). The ability to instrument each wall of the frontal sinus was recorded for the MELP, UBA, and combined approach. RESULTS: The UBA provided excellent access to the lateral frontal sinus in zones 2 and 3 (89% and 100%). The MELP provided poorer access in zone 3 (67%) but improved access in zone 1 (83%-100%). Access for zone 1 through the UBA was limited. The combined approach yielded 100% access to each frontal sinus boundary. CONCLUSION: The MELP in combination with the UBA/lateral trephination provides excellent access to each frontal sinus boundary. The UBA provides excellent access to the lateral frontal sinus but is limited medially by the SON.

Frontal Sinus Pneumatization Affects Height of the Lateral Lamella and Position of Anterior Ethmoidal Artery.

Preoperative evaluation of the frontal sinus (FS) and associated anatomical structures may reduce the risk of intraoperative complications and facilitate the management of potential complications. In this study, the authors aimed to evaluate relationship between FS pneumatization and critical anatomical structures. Paranasal sinus computerized tomography scans of 350 sides of 175 patients were evaluated. The pneumatization pattern of the FS, FS dimensions (on the axial, coronal, and sagittal slices), anterior ethmoidal artery, and depth of the of olfactory fossa were evaluated for every patient on both sides. There were 111 (63.4%) male and 64 (36.6%) female patients. The authors found a statistically significant correlation between the depth of olfactory fossa and the anterior ethmoidal artery position (P <0.001). As the FS pneumatization increases, the likelihood of the anterior ethmoid artery to run separately from the skull base also increases. Also, there was a statistically significant difference among the types in terms of the depth of the olfactory fossa (Kruskal-Wallis P = 0.002). The depth of the olfactory fossa increases depending on the increase of FS pneumatization.Our study shows that the olfactory fossa depth (skull-base depth) increases as FS pneumatization increases. In light of this information, the evaluation of the preoperative sinus computerized tomography scans will help in performing safer endoscopic sinus surgeries.

Supraorbital ethmoid cell: a consistent landmark for endoscopic identification of the anterior ethmoidal artery.

OBJECTIVE: To demonstrate that the supraorbital ethmoid cell (SOEC) is a consistent and reliable landmark in identification of the anterior ethmoidal artery (AEA). STUDY DESIGN: Retrospective radiographic study. SETTING: Tertiary care rhinology practice. SUBJECTS AND METHODS: The computed tomography (CT) scans for 78 consecutive patients were evaluated for the presence of SOECs, degree of pneumatization, and location of the AEA in relation to fixed anatomic structures. Forty-one patients with normal SOECs were identified and compared with a group of 15 patients with pathological expansion of the SOEC secondary to inflammatory disease. The CT findings were correlated with endoscopic findings. RESULTS: The incidence of SOECs was 53%. Compared to normal SOECs, expanded SOECs had significantly greater pneumatization laterally (9.3 vs 18.5 mm, respectively; P < .0001) and AEAs that were significantly farther from the skull base (1.3 vs 6.6 mm, respectively; P < .0001). The distance between the AEA and the nasal beak was similar between the 2 groups (P = .1). More importantly, 68 of 68 sides with normal SOECs (100%) demonstrated the AEA within or in continuity with the posterior border of the SOEC opening. In patients with pathological expansion, the AEA remained within the posterior border of the SOEC opening in 19 of 19 sides (100%), despite significant expansion of the cell superolaterally. CONCLUSION: This is the first study to demonstrate a consistent landmark to identify the AEA even in cases of distorted anatomy of the frontal recess. Identifying the SOEC is a practical and reliable technique for minimizing the risk of injury to the AEA during frontal recess surgery.

Is there any relationship between the frontal cell and the Agger nasi cell and the localization of the anterior ethmoid artery?

OBJECTIVES: In this article, we examined the effect of the presence or absence of a frontal cell or an Agger nasi cell on the localization of the anterior ethmoid artery. PATIENTS AND METHODS: Coronal paranasal sinus computed tomography scans on 110 sides of 61 patients (35 males, 26 females; mean age 35.6 ± 12.7 years; range 15 to 72 years) who underwent surgery for septal deviation, concha bullosa, antrochoanal polyp between September 2006 and February 2008 were retrospectively evaluated and the anterior ethmoid foramen localization was measured according to the anterior nasal spine. The correlations of these measurements with the presence and absence of a frontal cell and an Agger nasi cell were investigated. RESULTS: The measurement of the anterior ethmoidal foramen according to anterior nasal spine was 18.2 ± 8.8 mm in the absence of an Agger nasi cell and was 20.3 ± 6.6 mm in the presence of an Agger nasi cell. This distance was measured as 20.0 ± 7.3 mm when the frontal cell was not determined. This measurement was 20.2 ± 6.5 mm in the presence of a frontal cell. According to the frontal cell types the results of the measurements were 20.5 ± 5.9 mm, 18.9 ± 8 mm, 20.6 ± 7.3 mm, for type 1, type 2 and type 3, respectively. Our results revealed that there were no significant relationship between the presence or absence of a frontal cell and an Agger nasi cell and the localization of the anterior ethmoidal foramen. CONCLUSION: The results of this study showed that the presence or absence of these cells does not affect localization of the anterior ethmoid artery.

Forehead anatomy: arterial variations and venous link of the midline forehead flap.

The largest prospective cadaver study done over a 3-year period to investigate the arterial variations of the forehead is presented. The primary goal was to find anatomical support for various forehead flaps previously designed. Thirty cadaver foreheads (60 hemi-foreheads) were dissected from deep to superficial to identify arterial variations. The arteries were filled with a latex solution prior to dissection. The results show that the supratrochlear and dorsal nasal arteries have a relatively constant origin. Vertical (VB), oblique (OB), medial (MB) and lateral branches (LB) of the supraorbital artery were identified. The frontal branch of the superficial temporal artery (FBSTA) was found to continue in the direction of the scalp at the lateral orbital rim vertical line and gave off a transverse branch, the transverse frontal artery (TFA), to supply the forehead. The oblique branch of the supraorbital artery (OBSOA) most often anastomosed with either the transverse frontal artery or the frontal branch of the superficial temporal artery at the lateral orbital rim vertical line. A central artery (CA) was consistently found originating from the dorsal nasal artery usually 5mm from its origin. The central artery had a constant anastomosis with the opposite central artery in the inferior transverse third of the forehead. The central artery was not easily identifiable in the superior third of the forehead. The angular artery (AA) was found to have a variable termination. The angular artery could communicate with the supratrochlear artery (STrA) at the supraorbital rim (SOR) or it could continue up into the forehead medial to the STrA. This artery was called the paracentral artery (PCA). The central artery, paracentral artery and supratrochlear artery have an important relationship with the most prominent central vein that is relevant to flap construction. The significance of the central artery and vein favours the median forehead flap as anatomically superior and the prominent central vein is a constant landmark on which to select the side of the pedicle. Clear landmarks for defining the pedicle base for the median forehead flap are provided.

Paranasal and orbital anatomy revisited: identification of the ethmoid arteries on coronal CT scans.

OBJECTIVE: The aim of this study was to identify recognizable landmarks on coronal CT (CCT) scans for the localization of the anterior and posterior ethmoid arteries, which are important anatomic structures and surgical landmarks within the ethmoid sinuses. MATERIALS AND METHODS: Four series of plastinated cadaver specimens and 80 CCT examinations were evaluated to identify the anatomical landmarks that define the course of the anterior and posterior ethmoid arteries within the ethmoid sinuses. RESULTS: The following anatomic landmarks: the indentations into the medial orbital wall, the relationship between the superior oblique and medial rectus orbital muscles, and the lateral ethmoid fovea wall thinning proved to be useful CCT landmarks for the localization of the anterior and posterior ethmoid arteries. CONCLUSION: The results of this study suggest that familiarity with the above-mentioned landmarks on routine CCT images facilitates the localization of the anterior and posterior ethmoid arteries as they enter the ethmoid sinus.

Mammalian frontal diploic vein and the human foramen caecum.

The course of the frontal diploic vein in the mole Talpa and the tree shrew Tupaia is described and compared to the frontal diploic vein of other mammals. The frontal diploic vein in Talpa and Tupaia connects the dorsal sagittal sinus to the veins of the orbit and has an emissary function. In certain other mammals it has a diploic function and may drain towards the orbit (e.g., Orycteropus) or towards the dorsal sagittal sinus (e.g., Didelphis). The frontal diploic vein of these mammals is not homologous to the vein of the human foramen caecum, but to the human frontal diploic vein. The vein of the foramen caecum is a problematic structure: its incidence in embryos and children is not clear.