Sellar, suprasellar, and parasellar masses: Imaging features and neurosurgical approaches

The sellar, suprasellar, and parasellar space contain a vast array of pathologies, including neoplastic, congenital, vascular, inflammatory, and infectious etiologies. Symptoms, if present, include a combination of headache, eye pain, ophthalmoplegia, visual field deficits, cranial neuropathy, and endocrine manifestations. A special focus is paid to key features on CT and MRI that can help in differentiating different pathologies. While most lesions ultimately require histopathologic evaluation, expert knowledge of skull base anatomy in combination with awareness of key imaging features can be useful in limiting the differential diagnosis and guiding management. Surgical techniques, including endoscopic endonasal and transcranial neurosurgical approaches are described in detail.

Skull Base Anatomy in Patients with Bilateral Choanal Atresia: A Radiographic Study

Background The risk of skull base injury during choanal atresia repair can be mitigated via thorough understanding of skull base anatomy. There is a paucity of data describing differences in skull base anatomy between patients with coloboma, heart defects, atresia choanae, growth retardation, genital abnormalities, and ear abnormalities (CHARGE) syndrome and those without. Objectives The aim of this study was to measure nasal and skull base anatomy in patients with isolated bilateral choanal atresia (BCA), CHARGE syndrome, and other syndromic congenital anomalies. Methods Retrospective chart review of patients with bilateral choanal atresia and computed tomography of the face between 2001 and 2019 were evaluated. Choanal width, height, mid-nasal height, and skull base slope were measured radiographically. Differences in anatomy between healthy patients, those with CHARGE syndrome, and those with other congenital anomalies were compared. Results Twenty-one patients with BCA and relevant imaging were identified: 7 with isolated BCA, 6 with CHARGE syndrome, and 8 with other congenital anomalies. A t-test indicated insignificant difference in skull base slope, choanal height, choanal width, or mid-nasal skull base height between isolate BCA cases and patients with any congenital anomaly. When comparing CHARGE to isolated BCA cases, mid-nasal height was shorter in CHARGE patients (p = 0.03). There were no differences in measurements between patients with congenital anomalies excluding CHARGE (p > 0.05). Two patients in the congenital anomaly group were found to have bony skull base defects preoperatively. Conclusion This study represents the largest description of skull base and nasal anatomy in patients with CHARGE syndrome and BCA. Surgeons should be aware of the lower skull base in CHARGE patients to avoid inadvertent skull base injury.

Minimally Invasive Mini-orbitozygomatic Approach for Clipping an Anterior Communicating Artery Aneurysm: Virtual Reality Surgical Planning

Virtual reality (VR) has increasingly been implemented in neurosurgical practice. A patient with an unruptured anterior communicating artery (AcoA) aneurysm was referred to our institution. Imaging data from computed tomography angiography (CTA) was used to create a patient specific 3D model of vascular and skull base anatomy, and then processed to a VR compatible environment. Minimally invasive approaches (mini-pterional, supraorbital and mini-orbitozygomatic) were simulated and assessed for adequate vascular exposure in VR. Using an eyebrow approach, a mini-orbitozygomatic approach was performed, with clip exclusion of the aneurysm from the circulation. The step-by-step process of VR planning is outlined, and the advantages and disadvantages for the neurosurgeon of this technology are reviewed.

Surgery for diaphragma sellae meningioma: how I do it

Background Surgery for diaphragma sellae meningiomas (DSM) remains challenging due to the intimate neurovascular relationships of the tumor. Excision of DSM along with a decompression of the optic apparatus requires a good knowledge of the skull base anatomy and a precise preoperative evaluation of the tumor extensions. Method We describe the key steps of transcranial approach for DSM with a video illustration. The surgical anatomy is described along with the advantages and limitations of this approach. Conclusions The transcranial approach allows a safe tumor excision with an early and adequate control of the neurovascular structures, while minimizing postoperative CSF rhinorrhea.

Radiological Anatomy of the Olfactory Fossa: Is Skull Base Anatomy Really Ever “Safe”?

Objective Computed tomography (CT) is a powerful tool for delineating the anatomy of the anterior skull base. The goal of this study is to further characterize the relevant anatomical features of this area, along with other parameters important for endoscopic sinus surgery. Design Retrospective case review. Setting Tertiary care hospital. Participants Thirty patients who had CT scans of the paranasal sinuses. Main Outcome Measures The following features were assessed using image analysis software: olfactory fossa depth, the length and angle of the lateral lamella, fovea ethmoidalis length and shape, ethmoid roof height and slope, and the position and course of the anterior ethmoid artery. Statistical analysis was performed assessing for differences in the above parameters. Results The mean olfactory fossa depth of the anterior and posterior skull base was 3.4 ± 1.1 and 2.4 ± 0.9 mm, respectively (p < 0.05). The mean lateral lamella length was 3.6 ± 0.9 mm, which did not demonstrate significant variability. The angle of the lateral lamella varied significantly by skull base position, measuring 63.1 ± 17.8 degrees anteriorly, and 39.1 ± 17.9 degrees posteriorly (p < 0.05). In scans classified as a Keros type I, 25.3% had lateral lamellae longer than 4 mm. Furthermore, 43.7% had lateral lamellae with angles less than 45 degrees. Moving anteriorly, the posterior skull base sloped downward in 46.7% of patients. Conclusion Thorough preoperative assessment of CT scans is crucial to understanding the inherent variability of skull base anatomy. Even “safe” anatomy can still contain features such as long and acutely angled lateral lamella, which may predispose patients to iatrogenic injury.