Radiological outcomes for endovascular treatment of posterior communicating artery aneurysms: a retrospective multicenter study of the occlusion rate.

Although several innovations in techniques and implantable devices were reported over the last decades, a consensus on the best endovascular treatment for intracranial aneurysms originating from the posterior communicating artery is still missing. This work investigates radiological outcomes of different endovascular techniques for posterior communicating artery aneurysms treatment in a retrospective multi-centric cohort. We included patients endovascularly treated for posterior communicating artery aneurysms from 2015 through 2020 in six tertiary referral hospitals. We evaluated the relationship between patients and aneurysms characteristics, baseline neurological status, radiological outcomes, and the different endovascular techniques. Overall, 250 patients were included in this study. Simple coiling was the most frequent treatment in 171 patients (68%), followed by flow-diverter stenting in 32 cases (13%). Complete occlusion was reported in 163 patients (65%), near-complete occlusion in 43 (17%), and incomplete occlusion in 44 (18%). Radiological follow-up was available for 247 (98%) patients. The occlusion rate was stable in 149 (60%), improved in 49 (19%), and worsened in 51 (21%). No significant difference in exclusion rate was seen between ruptured and unruptured aneurysms at the last follow-up (p = 0.4). Posterior communicating artery thrombosis was reported in 25 patients (9%), transient ischemic attack in 6 (2%), and in 38 patients (15%), subsequent procedures were needed due to incomplete occlusion or reperfusion. Endovascular strategies for posterior communicating artery aneurysms represent effective and relatively safe treatments. Simple coiling provides a higher immediate occlusion rate, although recanalization has been frequently reported, conversely, flow-diversion devices provide good long-term radiological outcomes.

Efficacy of Microsurgical Sublabial Approach (MSA) Versus Endoscopic Endonasal Approach (EEA) for the Treatment of Pituitary Adenomas Based on Radiological and Hormonal Outcome.

BACKGROUND: The purpose of this study was to compare the surgical efficacy of the microsurgical sublabial approach (MSA) versus the endoscopic endonasal approach (EEA) for the treatment of pituitary adenomas, based on short-term (12 months) radiological and endocrinological follow-up. METHODS: One hundred and fourteen patients affected by pituitary adenoma were enrolled at our Unit between January 2007 and February 2012; 72 were treated with MSA, and 42 with EEA. The preoperative parameters considered were: type of lesion (secreting or nonsecreting), lesion size, presence of intralesional hemorrhage, lesion perimeter (nodular vs. uniform), intrasellar vs. suprasellar, involvement of cavernous sinus, and osteodural infiltration. Hormonal assays and magnetic resonance imaging (MRI) scans were performed at 12 months after the surgical procedure. RESULTS: Univariate analysis of the data documented a statistically significant difference in favor of MSA for the subgroups of secreting adenomas (90.9 % vs. nonsecreting 48.3 %), microadenomas (100 % vs. macroadenomas 57.1 %), adenomas without osteodural infiltration (87.5 % vs. 55.5 % with the infiltration) or those without intralesional hemorrhage (75 % vs. 45.9 % with the hemorrhage), and growth hormone (GH) adenomas (88.8 % vs. 43.7 %). Multivariate analysis confirmed the greater effectiveness of MSA for the treatment of micro-secreting adenomas. CONCLUSIONS: Recent advances in the EEA for treating pituitary adenomas could lead to this modality replacing the microsurgical technique. In our experience the MSA allowed us to achieve better results in the treatment of microadenomas.

The artery of Wollschlaeger and Wollschlaeger: an anatomical-clinical illustration.

The artery of Wollschlaeger and Wollschlaeger is an underreported yet important branch of the superior cerebellar artery. This artery feeds the adjacent tentorium and becomes enlarged and elongated in cases of vascular tumours and malformations of the tentorium. The present report is the first anatomical depiction of this artery in the literature.

Early Neurosurgical Education in the Era of Distant Learning: Incorporating Virtual Reality and Cadaveric Specimen Demonstrations.

BACKGROUND: Virtual reality (VR) has emerged as a powerful tool for neuroanatomy education of post-graduated medical trainees. However, its use in early training, such as of undergraduate, medical and physician assistant students, in neurosurgery has not been evaluated. We also have limited insight into how VR may be integrated with traditional teaching methods. METHODS: We created the first of its kind elective course on neuroanatomy for medical students incorporating lecture-style didactics, case-based VR activities and cadaveric dissections. The course ran entirely remotely with each student tuning into class with their own VR headset. We asked the students to self-report their level of confidence with the material and complete knowledge quizzes, which were compared in aggregate between pre- vs post-course, and pre- vs post- each session. RESULTS: 66.6% of students rated teaching quality of the course as excellent, and 33.3% as satisfactory. Most students (77.7-88.8%) also described the course as having a positive impact on their training. On aggregate analysis, the cohort reported increased levels of confidence in their understanding of neuroanatomy (mean 2.75 vs 5.4, p=0.02), neurosurgical approaches (mean 1.25 vs 5.7, p<0.0001) and the use of VR in neurosurgery (mean 1.5 vs 6.1, p<0.0001). Objectively, the cohort also performed better on post-session assessments, a difference which was statistically significant at p<0.05, in all but the first assessment. CONCLUSIONS: Integration of VR with traditional pedagogical tactics is well received by the learners and contributes to measurable learning outcomes. Our experience informs the future use of VR tools in medical education.

Lateral compartment of the cavernous sinus from the endoscopic endonasal approach: anatomical considerations and surgical relevance to adenoma surgery.

OBJECTIVE: The cavernous sinus (CS) has 4 compartments: superior, inferior, posterior, and lateral. Among these, the lateral compartment is the most common location for residual tumor, given the risk of neurovascular injury. The authors' study aimed to delineate the anatomical landmarks in this area and illustrate the technical nuances of the lateral transcavernous approach. METHODS: Twenty-two colored silicone-injected specimens were dissected via an endoscopic endonasal approach to the lateral compartment of the CS. The anatomical landmarks and the internal carotid artery (ICA) mobilization technique were investigated. Two illustrative cases are provided. RESULTS: The lateral compartment of the CS is bounded by the carotid-oculomotor membrane (COM) and optic strut as the roof and the petrolingual ligament and lingual process as the floor. It is divided into 2 asymmetrical subcompartments: the upper, larger subcompartment, located superior to the abducens nerve, accommodates the lateral parasellar ligament (LPL), inferolateral trunk (ILT), and branches of the tentorial artery; and the lower, smaller subcompartment, inferior to the abducens nerve, accommodates only the sympathetic nerve branches as they join the abducens nerve. The LPL is a well-defined ligamentous band and was identified in 38 (86%) hemispheres with 2 distinct configurations: 1) robust LPL (59%), with highly compacted ligamentous bands tightly adherent to the ICA; and 2) dispersed LPL (27%), with less compaction and adherence to ICA. The main attachment of the LPL to the cavernous ICA was most commonly observed at the horizontal ICA segment (55%), followed by the anterior (18%) and posterior (14%) genua. The ILT, as the main vessel in the lateral compartment, was identified in 41 (93%) hemispheres and originated from the horizontal ICA segment (80%) or the anterior genu (14%), from either the lateral (52%) or inferior (41%) aspect of the cross-section of the ICA. In 64% of hemispheres, the LPL wrapped the ILT, abducens nerve, and sympathetic nerve to form a broad and firm neurovascular-ligamental complex. Transection of the LPL, ILT, and COM enables medial ICA mobilization and enhances access to the lateral compartment of the CS, potentially increasing the exposure width by 6 ± 1 mm. CONCLUSIONS: This study provides valuable insights into the anatomical intricacies of the lateral compartment of the CS and underscores the potential benefits of the endoscopic endonasal lateral transcavernous approach. Further clinical applications are essential for validating these findings and optimizing surgical outcomes.

Endoscopic endonasal pituitary sacrifice for select tumors with retrochiasmatic and/or retrosellar extension: surgical anatomy, operative technique, and case series.

OBJECTIVE: Tumors located in the retrochiasmatic region with extension to the third ventricle might be difficult to access when the pituitary-chiasmatic corridor is narrow. Similarly, tumor extension into the interpeduncular and retrosellar space poses a major surgical challenge. Pituitary transposition techniques have been developed to gain additional access. However, when preoperative pituitary function is already impaired or the risk of postoperative panhypopituitarism (PH) is considered to be particularly high, removal of the pituitary gland (PG) might be the preferred option to increase the working corridor. The aim of this study was to describe the relevant surgical anatomy, operative steps, and clinical experience with the endoscopic endonasal pituitary sacrifice (EEPS) and transsellar approach. METHODS: This study comprised anatomical dissections to highlight the relevant surgical steps and a retrospective case series reporting clinical characteristics, indications, and outcomes of patients who underwent EEPS. The surgical technique is as follows: both lateral opticocarotid recesses are exposed laterally, the limbus sphenoidale superiorly, and the sellar floor inferiorly. After opening the dura, the PG is detached circumferentially and mobilized off the medial walls of the cavernous sinuses. The descending branches of the superior hypophyseal artery are coagulated, and the stalk is transected. After removal of the PG, drilling of the dorsum sellae and bilateral posterior clinoidectomies are performed to gain access to the hypothalamic region, interpeduncular, and prepontine cisterns. RESULTS: From 2018 to 2023, 11 patients underwent EEPS. The cohort comprised mostly tuberoinfundibular craniopharyngiomas (n = 8, 73%). Seven (64%) patients had partial or complete anterior PG dysfunction preoperatively, while 4 (36%) had preoperative diabetes insipidus. Because of the specific tumor configuration, the chance of preserving endocrine function was estimated to be very low in patients with intact function. The main reasons for pituitary sacrifice were impaired visibility and surgical accessibility to the retrochiasmatic and retrosellar spaces. Gross-total tumor resection was achieved in 10 (91%) patients and near-total resection in 1 (9%) patient. Two (18%) patients experienced a postoperative CSF leak, requiring surgical revision. CONCLUSIONS: When preoperative pituitary function is already impaired or the risk for postoperative PH is considered particularly high, the EEPS and transsellar approach appears to be a feasible surgical option to improve visibility and accessibility to the retrochiasmatic hypothalamic and retrosellar spaces, thus increasing tumor resectability.

Impact of Frailty on Surgical Outcomes of Patients With Cushing Disease Using the Multicenter Registry of Adenomas of the Pituitary and Related Disorders Registry.

BACKGROUND AND OBJECTIVES: Despite growing interest in how patient frailty affects outcomes (eg, in neuro-oncology), its role after transsphenoidal surgery for Cushing disease (CD) remains unclear. We evaluated the effect of frailty on CD outcomes using the Registry of Adenomas of the Pituitary and Related Disorders (RAPID) data set from a collaboration of US academic pituitary centers. METHODS: Data on consecutive surgically treated patients with CD (2011-2023) were compiled using the 11-factor modified frailty index. Patients were classified as fit (score, 0-1), managing well (score, 2-3), and mildly frail (score, 4-5). Univariable and multivariable analyses were conducted to examine outcomes. RESULTS: Data were analyzed for 318 patients (193 fit, 113 managing well, 12 mildly frail). Compared with fit and managing well patients, mildly frail patients were older (mean ± SD 39.7 ± 14.2 and 48.9 ± 12.2 vs 49.4 ± 8.9 years, P < .001) but did not different by sex, race, and other factors. They had significantly longer hospitalizations (3.7 ± 2.0 and 4.5 ± 3.5 vs 5.3 ± 3.5 days, P = .02), even after multivariable analysis (ß = 1.01, P = .007) adjusted for known predictors of prolonged hospitalization (age, Knosp grade, surgeon experience, American Society of Anesthesiologists grade, complications, frailty). Patients with mild frailty were more commonly discharged to skilled nursing facilities (0.5% [1/192] and 4.5% [5/112] vs 25% [3/12], P < .001). Most patients underwent gross total resection (84.4% [163/193] and 79.6% [90/113] vs 83% [10/12]). No difference in overall complications was observed; however, venous thromboembolism was more common in mildly frail (8%, 1/12) than in fit (0.5%, 1/193) and managing well (2.7%, 3/113) patients (P = .04). No difference was found in 90-day readmission rates. CONCLUSION: These results demonstrate that mild frailty predicts CD surgical outcomes and may inform preoperative risk stratification. Frailty-influenced outcomes other than age and tumor characteristics may be useful for prognostication. Future studies can help identify strategies to reduce disease burden for frail patients with hypercortisolemia.

Multicenter Registry of Adenomas of the Pituitary and Related Disorders: Initial Description of Cushing Disease Cohort, Surgical Outcomes, and Surgeon Characteristics.

BACKGROUND AND OBJECTIVES: To address the lack of a multicenter pituitary surgery research consortium in the United States, we established the Registry of Adenomas of the Pituitary and Related Disorders (RAPID). The goals of RAPID are to examine surgical outcomes, improve patient care, disseminate best practices, and facilitate multicenter surgery research at scale. Our initial focus is Cushing disease (CD). This study aims to describe the current RAPID patient cohort, explore surgical outcomes, and lay the foundation for future studies addressing the limitations of previous studies. METHODS: Prospectively and retrospectively obtained data from participating sites were aggregated using a cloud-based registry and analyzed retrospectively. Standard preoperative variables and outcome measures included length of stay, unplanned readmission, and remission. RESULTS: By July 2023, 528 patients with CD had been treated by 26 neurosurgeons with varying levels of experience at 9 academic pituitary centers. No surgeon treated more than 81 of 528 (15.3%) patients. The mean ± SD patient age was 43.8 ± 13.9 years, and most patients were female (82.2%, 433/527). The mean tumor diameter was 0.8 ± 2.7 cm. Most patients (76.6%, 354/462) had no prior treatment. The most common pathology was corticotroph tumor (76.8%, 381/496). The mean length of stay was 3.8 ± 2.5 days. The most common discharge destination was home (97.2%, 513/528). Two patients (0.4%, 2/528) died perioperatively. A total of 57 patients (11.0%, 57/519) required an unplanned hospital readmission within 90 days of surgery. The median actuarial disease-free survival after index surgery was 8.5 years. CONCLUSION: This study examined an evolving multicenter collaboration on patient outcomes after surgery for CD. Our results provide novel insights on surgical outcomes not possible in prior single-center studies or with national administrative data sets. This collaboration will power future studies to better advance the standard of care for patients with CD.

Intraoperative augmented reality fiber tractography complements cortical and subcortical mapping.

Augmented reality (AR) has been found to be advantageous in enhancing visualization of complex neuroanatomy intraoperatively and in neurosurgical education. Another key tool that allows neurosurgeons to have enhanced visualization, namely of white matter tracts, is diffusion tensor imaging (DTI) that is processed with high-definition fiber tractography (HDFT). There remains an enduring challenge in the structural-functional correlation of white matter tracts that centers on the difficulty in clearly assigning function to any given fiber tract when evaluating them through separated as opposed to integrated modalities. Combining the technologies of AR with fiber tractography shows promise in helping to fill in this gap between structural-functional correlation of white matter tracts. This novel study demonstrates through a series of three cases of awake craniotomies for glioma resections a technique that allows the first and most direct evidence of fiber tract stimulation and assignment of function or deficit in vivo through the intraoperative, real-time fusion of electrical cortical stimulation, AR, and HDFT. This novel technique has qualitatively shown to be helpful in guiding intraoperative decision making on extent of resection of gliomas. Future studies could focus on larger, prospective cohorts of glioma patients who undergo this methodology and further correlate the post-operative imaging results to patient functional outcomes.

Reappraisal of the anatomy of the frontotemporal branches of the facial nerve.

OBJECTIVE: The anatomy of the temporal branches of the facial nerve (FN) has been widely described in the neurosurgical literature because of its relevance in anterolateral approaches to the skull base and implication in frontalis palsies from these approaches. In this study, the authors attempted to describe the anatomy of the temporal branches of the FN and identify whether there are any FN branches that cross the interfascial space of the superficial and deep leaflets of the temporalis fascia. METHODS: The surgical anatomy of the temporal branches of the FN was studied bilaterally in 5 embalmed heads (n = 10 extracranial FNs). Exquisite dissections were performed to preserve the relationships of the branches of the FN and their relationship to the surrounding fascia of the temporalis muscle, the interfascial fat pad, the surrounding nerve branches, and their final terminal endpoints near the frontalis and temporalis muscles. The authors correlated their findings intraoperatively with 6 consecutive patients with interfascial dissection in which neuromonitoring was performed to stimulate the FN and associated twigs that were observed to be interfascial in 2 of them. RESULTS: The temporal branches of the FN stay predominantly superficial to the superficial leaflet of the temporal fascia in the loose areolar tissue near the superficial fat pad. As they course over the frontotemporal region, they give off a twig that anastomoses with the zygomaticotemporal branch of the trigeminal nerve, which crosses the superficial layer of the temporalis muscle, spanning the interfascial fat pad, and then pierces the deep temporalis fascial layer. This anatomy was observed in 10 of the 10 FNs dissected. Intraoperatively, stimulation of this interfascial segment yielded no facial muscle response up to 1 mA in any of the patients. CONCLUSIONS: The temporal branch of the FN gives off a twig that anastomoses with the zygomaticotemporal nerve, which crosses the superficial and deep leaflets of the temporal fascia. Interfascial surgical techniques aimed at protecting the frontalis branch of the FN are safe in their efforts to protect against frontalis palsy with no clinical sequelae when executed properly.

Cytodifferentiation of pituitary tumors influences pathogenesis and cavernous sinus invasion.

OBJECTIVE: Pituitary tumors (PTs) continue to present unique challenges given their proximity to the cavernous sinus, whereby invasive behavior can limit the extent of resection and surgical outcome, especially in functional tumors. The aim of this study was to elucidate patterns of cavernoinvasive behavior by PT subtype. METHODS: A total of 169 consecutive first-time surgeries for PTs were analyzed; 45% of the tumors were functional. There were 64 pituitary transcription factor-1 (PIT-1)-expressing, 62 steroidogenic factor-1 (SF-1)-expressing, 38 T-box transcription factor (TPIT)-expressing, and 5 nonstaining PTs. The gold standard for cavernous sinus invasion (CSI) was based on histopathological examination of the cavernous sinus medial wall and intraoperative exploration. RESULTS: Cavernous sinus disease was present in 33% of patients. Of the Knosp grade 3 and 4 tumors, 12 (19%) expressed PIT-1, 7 (11%) expressed SF-1, 8 (21%) expressed TPIT, and 2 (40%), were nonstaining (p = 0.36). PIT-1 tumors had a significantly higher predilection for CSI: 53% versus 24% and 18% for TPIT and SF-1 tumors, respectively (OR 6.08, 95% CI 2.86-13.55; p < 0.001). Microscopic CSI-defined as Knosp grade 0-2 tumors with confirmed invasion-was present in 44% of PIT-1 tumors compared with 7% and 13% of TPIT and SF-1 tumors, respectively (OR 11.72, 95% CI 4.35-35.50; p < 0.001). Using the transcavernous approach to excise cavernous sinus disease, surgical biochemical remission rates for patients with acromegaly, prolactinoma, and Cushing disease were 88%, 87%, and 100%, respectively. The granule density of PIT-1 tumors and corticotroph functional status did not influence CSI. CONCLUSIONS: The likelihood of CSI differed by transcription factor expression; PIT-1-expressing tumors had a higher predilection for invading the cavernous sinus, particularly microscopically, compared with the other tumor subtypes. This elucidates a unique cavernoinvasive behavior absent in cells from other lineages. Innovative surgical techniques, however, can mitigate tumor behavior and achieve robust, reproducible biochemical remission and gross-total resection rates. These findings can have considerable implications on the surgical management and study of PT biology and behavior.

Endoscopic Endonasal Transtuberculum Approach for Pediatric Tuberoinfundibular Craniopharyngioma: 2-Dimensional Operative Video.

INDICATIONS CORRIDOR AND LIMITS OF EXPOSURE: The endoscopic endonasal transtuberculum approach grants access to suprasellar and retrochiasmatic lesions with hypothalamic involvement. Here, we present a case of a 13-year-old boy with a history of stunted growth, decreased vision, headaches, and low energy with a tuberoinfundibular craniopharyngioma. The patient consented to the procedure. ANATOMIC ESSENTIALS NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT: Evaluation of the sphenoid sinus pneumatization, internal carotid artery disposition, presence of clinoidal rings, variations of the infrachiasmatic corridor (optic chiasm location, height of dorsum sella), and location of the pituitary stalk are crucial for surgical strategy. ESSENTIALS STEPS OF THE PROCEDURE: Harvesting of nasoseptal flap and access to the sphenoid sinus; drilling the sella, tuberculum, and chiasmatic sulcus up to the limbus sphenoidalis and laterally exposing the clinoidal carotid artery segment; wide dural opening to the level of distal rings inferolaterally and falciform ligaments superolaterally; identification and coagulation of superior hypophyseal branches providing tumor supply; intracapsular dissection and debulking and subpial sharp dissection at the hypothalamic tumor interface to achieve complete removal; and reconstruction with inlay collagen, fascia lata, and nasoseptal flap. PITFALLS/AVOIDANCE OF COMPLICATIONS: Preservation of the superior hypophyseal arteries and stalk is essential for preventing pituitary dysfunction. Preoperative reckoning of hypothalamic invasion and identification of adequate interface aids in avoiding complications. To reduce CSF leak risk, multilayer reconstruction was performed and lumbar drain placed postoperatively. VARIANTS AND INDICATIONS FOR THEIR USE: For retroclival extension, intradural pituitary transposition should be considered to expand the corridor; in patients with preoperative hypopituitarism, pituitary sacrifice is most effective to increase retroclival access.

Combined transpetrosal approach for giant petroclival meningioma: 2-dimensional operative video.

Petroclival meningiomas are extremally challenging lesions due to their deep location and close relation to critical neurovascular structures. Several approaches have been described to achieve gross-total resection with low morbidity and mortality. In this 2-dimensional operative video, the authors show a simultaneous combined transpetrosal approach. The patient is a 44-year-old woman with an 8-month history of gait imbalance with evidence of a giant petroclival meningioma on neuroimaging. She underwent a combined middle fossa approach with anterior petrosectomy and retrosigmoid/retrolabyrinthine approach to achieve gross-total tumor resection. The postoperative course was characterized by trigeminal neuralgia, and neuroimaging showed gross-total resection of the tumor. The video can be found here: https://stream.cadmore.media/r10.3171/2022.1.FOCVID21248.

Anatomic Considerations in Endoscopic Pituitary Surgery.

The pituitary gland is a small gland at the base of the skull controlling many physiologic processes through its regulation of primary endocrine glands. Pathologies of the pituitary gland and sellar space are wide ranging and most commonly include pituitary adenomas but can also encompass pituitary hyperplasia, other benign nonadenomatous tumors, cysts, and primary and metastatic malignancy. At present, the endoscopic approach has been established as a safe and effective approach to surgical management of pituitary pathology. A detailed understanding of the sella and parasellar anatomy from an endoscopic approach is imperative to performing safe endoscopic surgery in this area.

Microsurgical anatomy of the dorsal clinoidal space: implications for endoscopic endonasal parasellar surgery.

OBJECTIVE: The clinoidal venous space dorsal to the internal carotid artery (ICA) has not been well studied given its inaccessibility due to obstruction by the ICA during transcranial surgery. The evolution of endoscopic endonasal surgery has provided a new perspective into the clinoidal space and a new route for paraclinoidal lesions. Understanding the dorsal clinoidal space (DCS) is vital in planning and performing endoscopic endonasal surgery in the parasellar region. A detailed and precise description of the DCS from the endonasal perspective has not yet been provided. The authors' goal in this study was to delineate the microsurgical anatomy of the DCS from an endoscopic endonasal perspective, emphasizing its surgical implications when treating invasive pituitary adenomas and other parasellar lesions. METHODS: An endoscopic endonasal transsellar approach was performed in 15 silicone-injected postmortem heads. Afterward, the sellar region was dissected through a transcranial approach using magnification ×3 to ×40 microscopy. The osseous, dural, and arterial relationships of the DCS and its architecture were investigated. The DCS's length, width, and depth were measured and its anatomical variations recorded. RESULTS: The DCS was identified in 90% of the specimens, and in most cases, its shape was a narrow rectangular pyramid, with its base oriented toward the sphenoid sinus and its apex toward the posterior clinoid process. It is delimited superiorly by the distal ring, inferiorly by the medial aspect of the proximal dural ring or caroticoclinoid ligament, laterally by the clinoidal ICA, and medially by the superior continuation of the medial wall of the cavernous sinus. The width, height, and length of the DCS were 4 ± 1, 4.5 ± 1.5, and 7 ± 2 mm, respectively. A fenestrated caroticoclinoid ligament is a potential route for tumor invasion from the cavernous sinus into the DCS. CONCLUSIONS: This report provides important anatomical descriptions of the DCS from endoscopic endonasal and transcranial perspectives that may facilitate the space's safe exposure for the removal of invasive adenomas, increasing total resection rates and minimizing the risk of injury to neurovascular structures.

Frontotemporal-Orbitozygomatic Approach and Its Variants: Technical Nuances and Video Illustration.

The frontotemporal-orbitozygomatic (FTOz) approach is an extension of the traditional pterional approach. It provides the neurosurgeon with a wide access to the skull base with minimal or no brain retraction needed; it also offers a panoramic view that enables various trajectories toward the anterior, middle, and central cranial fossae as well as the upper segment of the posterior cranial fossa. Intracranial lesions that can be addressed using the FTOz approach include large medial sphenoid wing and spheno-orbital meningiomas; suprasellar and parasellar tumors; lesions of the orbital apex, interpeduncular cistern, third ventricle, and upper paraclival regions; and anterior communicating artery and basilar-tip aneurysms. In this article, we discuss the advantages and disadvantages of the FTOz approach and describe related technical nuances and common pitfalls. Our goal was to provide an up-to-date report of this time-tested surgical approach using original high-quality dissections, 3-dimensional models, and 2-dimensional 4K videos to serve as a reliable and practical educational resource for neurosurgery trainees and junior neurosurgeons. A case example is also provided to show the 1-piece orbitozygomatic approach.

Intracranial Breakthrough Through Cavernous Sinus Compartments: Anatomic Study and Implications for Pituitary Adenoma Surgery.

BACKGROUND: Pituitary adenomas (PAs) with cavernous sinus (CS) invasion can extend into the intradural space by breaking through the CS walls. OBJECTIVE: To elaborate on the potential breakthrough route through CS compartments for invasive PAs and describe relevant surgical anatomy and technical nuances, with an aim to improve resection rates. METHODS: Twelve colored silicon-injected human head specimens were used for endonasal and transcranial dissection of the CS walls; ligaments, dural folds, and cranial nerves on each compartment were inspected. Two illustrative cases of invasive PA are also presented. RESULTS: The potential breakthrough routes through the CS compartments had unique anatomic features. The superior compartment breakthrough was delimited by the anterior petroclinoidal ligament laterally, posterior petroclinoidal ligament posteriorly, and interclinoidal ligament medially; tumor extended into the parapeduncular space with an intimate spatial relationship with the oculomotor nerve and posterior communicating artery. The lateral compartment breakthrough was limited by the anterior petroclinoidal ligament superiorly and ophthalmic nerve inferiorly; tumor extended into the middle fossa, displacing the trochlear nerve and inferolateral trunk to reach the medial temporal lobe. The posterior compartment breakthrough delineated by the Gruber ligament, petrosal process of the sphenoid bone, and petrous apex inferiorly, posterior petroclinoidal ligament superiorly, and dorsum sellae medially; tumor displaced or encased the abducens nerve and inferior hypophyseal artery and compressed the cerebral peduncle. CONCLUSION: The superior lateral and posterior components of the CS are potential routes for invasion by PAs. Better identification of CS breakthrough patterns is crucial for achieving higher gross total resection and remission rates.

Ideal trajectory for frontal ventriculostomy: Radiological study and anatomical study.

OBJECTIVE: Several techniques have been described to improve the accuracy of the freehand procedure for frontal ventriculostomy and reduce complications due to suboptimal placement or misplacement of the catheter tip. To date, none of the available studies have found a reliable, low cost and consistent technique. We aimed to provide a standardized protocol for freehand frontal ventriculostomy. METHODS: In the first part of the radiological study, 125 CT scans were used to measure the length of the catheter using 2 right-sided entry points. In the second part, a grid of 24 entry points on the frontal bone was used in 50 CT scans to record the distance from the cranial surface to the Foramen of Monro (FM). Ventriculostomy was performed on six cadaveric heads using a grid of 9 entry points, comparing a 5 ml syringe with the freehand technique to reach the target. RESULTS: The first part of the radiological study showed a length from the cranial surface to the FM was overall 67,38 ± 1,03 mm. For the second part, the mean length of the 24 selected points was 68,54 ± 2,73 mm without statistical difference. In the anatomical study, the FM was reached 8 times (14.8%) with the syringe vs 31 times (57.4%) with the freehand technique, and the ventricles 43 (79.6%) vs 37 (68.5%). The mean lengths from the skull to the FM were 71.33 ± 4.21 mm. CONCLUSIONS: In this study, we showed the optimal length of a frontal ventricular catheter. We have also demonstrated that the portion of the frontal bone above the superior temporal lines matches a sphere in which the center is the FM.

Microsurgical anatomy and the importance of the petrosal process of the sphenoid bone in endonasal surgery.

OBJECTIVE: The petrosal process of the sphenoid bone (PPsb) is a relevant skull base osseous prominence present bilaterally that can be used as a key surgical landmark, especially for identifying the abducens nerve. The authors investigated the surgical anatomy of the PPsb, its relationship with adjacent neurovascular structures, and its practical application in endoscopic endonasal surgery. METHODS: Twenty-one dried skulls were used to analyze the osseous anatomy of the PPsb. A total of 16 fixed silicone-injected postmortem heads were used to expose the PPsb through both endonasal and transcranial approaches. Dimensions and distances of the PPsb from the foramen lacerum (inferiorly) and top of the posterior clinoid process (PCP; superiorly) were measured. Moreover, anatomical variations and the relationship of the PPsb with the surrounding crucial structures were recorded. Three representative cases were selected to illustrate the clinical applications of the findings. RESULTS: The PPsb presented as a triangular bony prominence, with its base medially adjacent to the dorsum sellae and its apex pointing posterolaterally toward the petrous apex. The mean width of the PPsb was 3.5 ± 1 mm, and the mean distances from the PPsb to the foramen lacerum and the PCP were 5 ± 1 and 11 ± 2.5 mm, respectively. The PPsb is anterior to the petroclival venous confluence, superomedial to the inferior petrosal sinus, and inferomedial to the superior petrosal sinus; constitutes the inferomedial limit of the cavernous sinus; and delimits the upper limit of the paraclival internal carotid artery (ICA) before the artery enters the cavernous sinus. The PPsb is anterior and medial to and below the sixth cranial nerve, forming the floor of Dorello's canal. During surgery, gentle mobilization of the paraclival ICA reveals the petrosal process, serving as an accurate landmark for the location of the abducens nerve. CONCLUSIONS: This investigation revealed details of the microsurgical anatomy of the PPsb, its anatomical relationships, and its application as a surgical landmark for identifying the abducens nerve. This novel landmark may help in minimizing the risk of abducens nerve injury during transclival approaches, which extend laterally toward the petrous apex and cavernous sinus region.