Open-door extended endoscopic transorbital technique to the paramedian anterior and middle cranial fossae: technical notes, anatomomorphometric quantitative analysis, and illustrative case.

OBJECTIVE: The superior eyelid endoscopic transorbital approach (SETOA) provides a direct and short minimally invasive route to the anterior and middle skull base. Nevertheless, it uses a narrow corridor that limits its angles of attack. The aim of this study was to evaluate the feasibility and potential benefits of an "extended" conservative variant of the "standard" endoscopic transorbital approach-termed "open-door"-to enhance the exposure of lesions affecting the paramedian aspect of the anterior and middle cranial fossae. METHODS: First, the authors described the technical nuances of the open-door extended transorbital approach (ODETA). Next, they documented its morphometric advantages over standard SETOA. Finally, they provided a clinical-anatomical application to demonstrate enhanced exposure and better angles of attack to treat lesions occupying the paramedian anterior and middle cranial fossae. Five adult cadaveric specimens (10 sides) initially underwent standard SETOA and then extended open-door SETOA (ODETA to the paramedian anterior and middle fossae). The adjunct of hinge-orbitotomy, through three surgical steps and straddling the frontozygomatic suture, converted conventional SETOA to its extended open-door variant. CT scans were performed before dissection and uploaded to the neuronavigation system for quantitative analysis. The angles of attack on the axial plane that addressed four key landmarks, namely the tip of the anterior clinoid process (ACP), foramen rotundum (FR), foramen ovale (FO), and trigeminal impression (TI), were calculated for both operative techniques and compared. RESULTS: Hinge-orbitotomy of the extended open-door SETOA resulted in several surgical, functional, and esthetic advantages: it provided wider axial angles of attack for each of the target points, with a gain angle of 26.68° ± 1.31° for addressing the ACP (p < 0.001), 29.50° ± 2.46° for addressing the FR (p < 0.001), 19.86° ± 1.98° for addressing the FO (p < 0.001), and 17.44° ± 2.21° for addressing the lateral aspect of the TI (p < 0.001), while hiding the skin scar, avoiding temporalis muscle dissection, preserving flap vascularization, and decreasing the rate of bone infection and degree of orbital content retraction. CONCLUSIONS: The extended open-door technique may be specifically suited for selected patients affected by paramedian anterior and middle fossae lesions, with prevalent anteromedial extension toward the anterior clinoid, the foremost compartment of the cavernous sinus and FR and not completely controlled with the pure endoscopic transorbital approach.

Neoplasms and tumor-like lesions of the sellar region: imaging findings with correlation to pathology and 2021 WHO classification.

The sellar region represents a complex anatomical area, composed of multiple structures of different embryological derivation, including the skull base and the pituitary gland, along with vascular, nervous, and meningeal structures. Masses arising in this region include benign and malignant lesions arising from the pituitary gland itself, but also from vestigial embryological residues or surrounding tissues, that may require different therapeutic approaches. While assessing sellar region masses, the combination of clinical presentation and imaging features is fundamental to define hypotheses about their nature. MR represents the imaging modality of choice, providing information about the site of the lesion, its imaging features, and relation with adjacent structures, while CT is useful to confirm the presence of lesion calcifications or to reveal tumor invasion of bony structures. The aim of this pictorial review is to provide an overview of the common neoplasms and tumor-like conditions of the sellar region, according to the 2021 WHO Classification of Tumors of the Central Nervous System (fifth edition), with an emphasis on the radiologic-pathologic correlation. After a brief introduction on the anatomy of this region and the imaging and pathological techniques currently used, the most relevant MRI characteristics, clinical findings, and pathological data, including histologic and molecular features, will be shown and discussed, with the aim of facilitating an appropriate differential diagnosis among these entities.

Surgical Approaches to the Third Ventricle: An Update.

The third ventricle is located in the deepest part of the brain and is delimited by both telencephalic and diencephalic structures. Its location makes every surgical procedure inside or around it quite challenging, due to the distance from the surface to the fragility of the neurovascular structures that is necessary to dissect before entering its cavity and to the narrow surgical corridors through which it is necessary to work. Its geometric localization inside the cranial cavity and the anatomical relationship with the interhemispheric fissure offers nevertheless to the surgeon an impressive variety of surgical approaches, which allow to reach every millimeter of the third ventricle lumen. Mastering properly all these approaches requires an impressive anatomical knowledge, the best available technology, and most refined technical skills, making the surgery of the third ventricle a point of excellence in the evolution of each neurosurgeon. The development of neuronavigation and neuroendoscopy has been a revolution in neurosurgery in the last 20 years and offered special advantages for the surgery of the third ventricle. In fact, the narrow corridors of approach make the precision of the neuronavigation and the enlightenment and magnification of the neuroendoscopy especially useful to reach the third ventricle cavity and working inside or around it. This chapter reviews the history of the surgery of the third ventricle and offers an update of the variety of surgical corridors identified and of the technology now available to properly work through them and inside the third ventricle cavity.

Surgeon's Eyes on the Relevant Surgical Target.

The resolution of the naked eye has been a challenge for the neurosurgical endeavor since the very first attempts of cranial surgery, and advances have been achieved over the centuries, driven by a synergism between the application of emerging technology into the surgical environment and the expansion of the capabilities of neurosurgery. The understanding of the principles of the optical properties of lenses by Abbè (1840-1905) led to the introduction of loupes in the surgical practice, increasing the visual performance during macroscopic procedures. Modern neurosurgery began with the possibility of illumination and magnification of the surgical field as provided by the microscope. Pioneering contributions from Donaghy and Yasargil opened the way to the era of minimalism with reduction of operative corridors and surgical trauma through the adoption of the microsurgical technique. Almost at the same time, engineering mirabilia of Hopkins in terms of optics and lenses allowed for introduction of rigid and flexible endoscopes as a viable tool in neurosurgery. Nowadays, neurosurgeons are aware of and confident using effective and modern tools of visualization in their armamentarium. Herein we present a cogent review of the evolution of visualization tools in neurosurgery, with a special glimpse into the current development and future achievements.

The anterolateral triangle as window on the foramen lacerum from transorbital corridor: anatomical study and technical nuances.

OBJECTIVE: Neurosurgical indications for the superior eyelid transorbital endoscopic approach (SETOA) are rapidly expanding over the last years. Nevertheless, as any new technique, a detailed knowledge of the anatomy of the surgical target area, the operative corridor, and the specific surgical landmark from this different perspective is required for a safest and successful surgery. Therefore, the aim of this study is to provide, through anatomical dissections, a detailed investigation of the surgical anatomy revealed by SETOA via anterolateral triangle of the middle cranial fossa. We also sought to define the relevant surgical landmarks of this operative corridor. METHODS: Eight embalmed and injected adult cadaveric specimens (16 sides) underwent dissection and exposure of the cavernous sinus and middle cranial fossa via superior eyelid endoscopic transorbital approach. The anterolateral triangle was opened and its content exposed. An extended endoscopic endonasal trans-clival approach (EEEA) with exposure of the cavernous sinus content and skeletonization of the paraclival and parasellar segments of the internal carotid artery (ICA) was also performed, and the anterolateral triangle was exposed. Measurements of the surface area of this triangle from both surgical corridors were calculated in three head specimens using coordinates of its borders under image-guide navigation. RESULTS: The drilling of the anterolateral triangle via SETOA unfolds a space that can be divided by the course of the vidian nerve into two windows, a wider "supravidian" and a narrower "infravidian," which reveal different anatomical corridors: a "medial supravidian" and a "lateral supravidian," divided by the lacerum segment of the ICA, leading to the lower clivus, and to the medial aspect of the Meckel's cave and terminal part of the horizontal petrous ICA, respectively. The infravidian corridor leads medially into the sphenoid sinus. The arithmetic means of the accessible surface area of the anterolateral triangle were 45.48 ± 3.31 and 42.32 ± 2.17 mm2 through transorbital approach and endonasal approach, respectively. CONCLUSION: SETOA can be considered a minimally invasive route complementary to the extended endoscopic endonasal approach to the anteromedial aspect of the Meckel's cave and the foramen lacerum. The lateral loop of the trigeminal nerve represents a reliable surgical landmark to localize the lacerum segment of the ICA from this corridor. Nevertheless, as any new technique, a learning curve is needed, and the clinical feasibility should be proven.

The feasibility of three port endonasal, transorbital, and sublabial approach to the petroclival region: neurosurgical audit and multiportal anatomic quantitative investigation.

PURPOSE: The petroclival region represents the "Achille's heel" for the neurosurgeons. Many ventral endoscopic routes to this region, mainly performed as isolated, have been described. The aim of the present study is to verify the feasibility of a modular, combined, multiportal approach to the petroclival region to overcome the limits of a single approach, in terms of exposure and working areas, brain retraction and manipulation of neurovascular structures. METHODS: Four cadaver heads (8 sides) underwent endoscopic endonasal transclival, transorbital superior eyelid and contralateral sublabial transmaxillary-Caldwell-Luc approaches, to the petroclival region. CT scans were obtained before and after each approach to rigorously separate the contribution of each osteotomy and subsequentially to build a comprehensive 3D model of the progressively enlarged working area after each step. RESULTS: The addition of the contralateral transmaxillary and transorbital corridors to the extended endoscopic endonasal transclival in a combined multiportal approach provides complementary paramedian trajectories to overcome the natural barrier represented by the parasellar and paraclival segments of the internal carotid artery, resulting in significantly greater area of exposure than a pure endonasal midline route (8,77 cm2 and 11,14 cm2 vs 4,68 cm2 and 5,83cm2, extradural and intradural, respectively). CONCLUSION: The use of different endoscopic "head-on" trajectories can be combined in a wider multiportal extended approach to improve the ventral route to the most inaccessible petroclival regions. Finally, by combining these approaches and reiterating the importance of multiportal strategy, we quantitatively demonstrate the possibility to reach "far away" paramedian petroclival targets while preserving the neurovascular structures.

Persisting embryonal infundibular recess (PEIR) and transsphenoidal-transsellar encephaloceles: distinct entities or constituents of one continuum?

Persisting embryonal infundibular recess (PEIR) is a very rare anomaly of the floor of the third ventricle in which the embryonic morphology of the infundibular recess (IR) persists. The exact underlying mechanism of development of PEIR is unknown, and the anomaly has been reported as an isolated finding or in association with other conditions. On the other hand, trans-sphenoidal encephaloceles are the rarest form of basal encephaloceles. The trans-sphenoidal trans-sellar encephalocele (TSE) is the least common variant in which the pituitary gland, pituitary stalk, optic pathways, parts of the third ventricle and IR may be present within the encephalocele. We recently treated one patient with TSE. Based on the observed morphological similarity of the IR in our patient and in the published cases of PEIR, we reviewed the literature in order to validate the hypothesis that PEIR and TSE may possibly belong to one spectrum of malformations. Across the published reports, the morphology of the IR in TSE is very closely similar to PEIR. Moreover, radiological, patho-anatomical, and embryological evidence is in support to our hypothesis that PEIR and TSE are most likely the two extremes of the same continuum of malformations.

Primary ectopic orbital craniopharyngioma.

Craniopharyngiomas (CP) ectopic localizations off the midline outside the sellar-suprasellar region are very rare and most often associated to secondary tumor dissemination, being primary ectopic CPs extremely unusual. We herein report the first case of a primary ectopic craniopharyngioma within the orbit. A 15-year-old patient presented with progressive right ptosis, proptosis, and retro ocular pain. Magnetic resonance imaging (MRI) showed a predominantly cystic lesion, occupying the superolateral right corner of the orbit, outside the intraconal space with no evidence of intracranial involvement. An endoscopic transorbital eyelid approach was adopted. Pathology report disclosed a primary ectopic craniopharyngioma.

Aggressive pituitary neuroendocrine tumors: current practices, controversies, and perspectives, on behalf of the EANS skull base section.

Aggressive pituitary neuroendocrine tumors (APT) account for 10% of pituitary tumors. Their management is a rapidly evolving field of clinical research and has led pituitary teams to shift toward a neuro-oncological-like approach. The new terminology "Pituitary neuroendocrine tumors" (PitNet) that was recently proposed to replace "pituitary adenomas" reflects this change of paradigm. In this narrative review, we aim to provide a state of the art of actual knowledge, controversies, and recommendations in the management of APT. We propose an overview of current prognostic markers, including the recent five-tiered clinicopathological classification. We further establish and discuss the following recommendations from a neurosurgical perspective: (i) surgery and multi-staged surgeries (without or with parasellar resection in symptomatic patients) should be discussed at each stage of the disease, because it may potentialize adjuvant medical therapies; (ii) temozolomide is effective in most patients, although 30% of patients are non-responders and the optimal timeline to initiate and interrupt this treatment remains questionable; (iii) some patients with selected clinicopathological profiles may benefit from an earlier local radiotherapy and/or chemotherapy; (iv) novel therapies such as VEGF-targeted therapies and anti-CTLA-4/anti-PD1 immunotherapies are promising and should be discussed as 2nd or 3rd line of treatment. Finally, whether neurosurgeons have to operate on "pituitary adenomas" or "PitNets," their role and expertise remain crucial at each stage of the disease, prompting our community to deal with evolving concepts and therapeutic resources.

Prediction of pituitary adenoma surgical consistency: radiomic data mining and machine learning on T2-weighted MRI.

PURPOSE: Pituitary macroadenoma consistency can influence the ease of lesion removal during surgery, especially when using a transsphenoidal approach. Unfortunately, it is not assessable on standard qualitative MRI. Radiomic texture analysis could help in extracting mineable quantitative tissue characteristics. We aimed to assess the accuracy of texture analysis combined with machine learning in the preoperative evaluation of pituitary macroadenoma consistency in patients undergoing endoscopic endonasal surgery. METHODS: Data of 89 patients (68 soft and 21 fibrous macroadenomas) who underwent MRI and transsphenoidal surgery at our institution were retrospectively reviewed. After manual segmentation, radiomic texture features were extracted from original and filtered MR images. Feature stability analysis and a multistep feature selection were performed. After oversampling to balance the classes, 80% of the data was used for hyperparameter tuning via stratified 5-fold cross-validation, while a 20% hold-out set was employed for its final testing, using an Extra Trees ensemble meta-algorithm. The reference standard was based on surgical findings. RESULTS: A total of 1118 texture features were extracted, of which 741 were stable. After removal of low variance (n = 4) and highly intercorrelated (n = 625) parameters, recursive feature elimination identified a subset of 14 features. After hyperparameter tuning, the Extra Trees classifier obtained an accuracy of 93%, sensitivity of 100%, and specificity of 87%. The area under the receiver operating characteristic and precision-recall curves was 0.99. CONCLUSION: Preoperative T2-weighted MRI texture analysis and machine learning could predict pituitary macroadenoma consistency.

Multicenter external validation of the Zurich Pituitary Score.

PURPOSE: Recently, the Zurich Pituitary Score (ZPS) has been proposed as a new quantitative preoperative classification scheme for predicting gross total resection (GTR), extent of resection (EOR), and residual tumor volume (RV) in endoscopic pituitary surgery. We evaluated the external validity of the ZPS. METHODS: In three reference centers for pituitary surgery, the ZPS was applied and correlated to GTR, EOR, and RV. Furthermore, its inter-rater agreement was assessed. RESULTS: A total of 485 patients (53% male; age, 53.8 ± 15.7) were included. ZPS grades I, II, III, and IV were observed in 110 (23%), 270 (56%), 64 (13%), and 41 (8%) patients, respectively. GTR was achieved in 358 (74%) cases, with mean EOR of 87.6% ± 20.3% and RV of 1.42 ± 2.80 cm3. With increasing ZPS grade, strongly significant decreasing trends for GTR (I, 92%; II, 77%; III, 67%; IV, 15%; p < 0.001) and EOR (I, 93.8%; II, 89.9%; III, 88.1%; IV, 75.4%; p < 0.001) were found. Similarly, RV increased steadily ([cm3] I, 0.16; II, 0.61; III, 2.01; IV, 3.84; p < 0.001). We observed intraclass correlation coefficients of 0.837 (95% CI, 0.804-0.865) for intercarotid distance and 0.964 (95% CI, 0.956-0.970) for adenoma diameter, and Cohen's kappa of 0.972 (95% CI, 0.952-0.992) for the ZPS grades. CONCLUSIONS: Application of the ZPS in three external cohorts was successful. The ZPS generalized well in terms of GTR, EOR, and RV; demonstrated excellent inter-rater agreement; and can safely and effectively be applied as a quantitative classification of adenomas with relevance to surgical outcome.

Endoscopic endonasal and transorbital routes to the petrous apex: anatomic comparative study of two pathways.

BACKGROUND AND OBJECTIVE: Surgical approaches to the petrous apex region are extremely challenging; while subtemporal approaches and variations represent the milestone of the surgical modules to reach such deep anatomical target, in a constant effort to develop minimally invasive neurosurgical routes, the endoscopic endonasal approach (EEA) has been tested to get a viable corridor to the petroclival junction. Lately, another ventral endoscopic minimally invasive route, i.e., the superior eyelid endoscopic transorbital approach, has been proposed to access the most lateral aspect of the skull base, including the petrous apex region. Our anatomic study aims to compare and combine such two endoscopic minimally invasive pathways to get full access to the petrous apex. Three-dimensional reconstructions and quantitative and morphometric data have been provided. MATERIAL AND METHODS: Five human cadaveric heads (10 sides) were dissected. The lab rehearsals were run as follows: (i) preliminary pre-operative CT scans of each specimen, (ii) pre-dissection planning of the petrous apex removal and its quantification, (iii) petrous apex removal via endoscopic endonasal route, (iv) post-operative CT scans, (v) petrous apex removal via endoscopic transorbital route, and (v) final post-operative CT scan with quantitative analysis. Neuronavigation was used to guide all dissections. RESULTS: The two endoscopic minimally invasive pathways allowed a different visualization and perspective of the petrous apex, and its surrounding neurovascular structures. After both corridors were completed, a communication between the surgical pathways was highlighted, in a so-called connection area, surrounded by the following important neurovascular structures: anteriorly, the internal carotid artery and the Gasserian ganglion; laterally, the internal acoustic canal; superiorly, the abducens nerve, the trigeminal root, and the tentorium cerebelli; inferomedially, the remaining clivus and the inferior petrosal sinus; and posteriorly, the exposed area of the brainstem. Used in a combined fashion, such multiportal approach provided a total of 97% of petrous apex removal. In particular, the transorbital route achieved a mean of 48.3% removal in the most superolateral portion of the petrous apex, whereas the endonasal approach provided a mean of 48.7% bone removal in the most inferomedial part. The difference between the two approaches was found to be not statistically significant (p = 0.67). CONCLUSION: The multiportal combined endoscopic endonasal and transorbital approach to the petrous apex provides an overall bone removal volume of 97% off the petrous apex. In this paper, we highlighted that it was possible to uncover a common path between these two surgical pathways (endonasal and transorbital) in a so-called connection area. Potential indications of this multiportal approach may be lesions placed in or invading the petrous apex and petroclival regions that can be inadequately reached via transcranial paths or via an endonasal endoscopic route alone.

Prediction of high proliferative index in pituitary macroadenomas using MRI-based radiomics and machine learning.

PURPOSE: Pituitary adenomas are among the most frequent intracranial tumors. They may exhibit clinically aggressive behavior, with recurrent disease and resistance to multimodal therapy. The ki-67 labeling index represents a proliferative marker which correlates with pituitary adenoma aggressiveness. Aim of our study was to assess the accuracy of machine learning analysis of texture-derived parameters from pituitary adenomas preoperative MRI for the prediction of ki-67 proliferation index class. METHODS: A total of 89 patients who underwent an endoscopic endonasal procedure for pituitary adenoma removal with available ki-67 labeling index were included. From T2w MR images, 1128 quantitative imaging features were extracted. To select the most informative features, different supervised feature selection methods were employed. Subsequently, a k-nearest neighbors (k-NN) classifier was employed to predict macroadenoma high or low proliferation index. Algorithm validation was performed with a train-test approach. RESULTS: Of the 12 subsets derived from feature selection, the best performing one was constituted by the 4 highest correlating parameters at Pearson's test. These all showed very good (ICC ≥ 0.85) inter-observer reproducibility. The overall accuracy of the k-NN in the test group was of 91.67% (33/36) of correctly classified patients. CONCLUSIONS: Machine learning analysis of texture-derived parameters from preoperative T2 MRI has proven to be effective for the prediction of pituitary macroadenomas ki-67 proliferation index class. This might aid the surgical strategy making a more accurate preoperative lesion classification and allow for a more focused and cost-effective follow-up and long-term management.

The endoscopic endonasal approach for pediatric craniopharyngiomas: the key lessons learned.

PURPOSE: The aim of this study is to highlight the role of the endoscopic endonasal approach (EEA) in pediatric craniopharyngiomas by reviewing our experience and the key lessons learned from the application of this approach in children. METHODS: Between 1998 and 2017, 12 pediatric craniopharyngiomas were treated via EEA at our institution. Demographic data, preoperative assessment, tumor features, surgical results, complications, and recurrences were analyzed. RESULTS: Visual defects were the most frequent presenting sign. Seven craniopharyngiomas were infradiaphragmatic, and five were supradiaphragmatic. The EEA was successfully performed in all cases with no complication related to children's sinonasal anatomy. Gross total resection (GTR) rate was of 75%. Endocrinological disturbances improved in one case (20%) and worsened in three (60%). New onset of diabetes insipidus was observed in four (36%) children. Visual defect improved in 91% of cases, with no new postoperative deficit. Postoperative cerebrospinal fluid (CSF) leak occurred in one patient (8%). Three patients (27%) experienced tumor regrowth, and one craniopharyngioma recurred (mean follow-up, 78 months). CONCLUSIONS: The EEA offers a straight route to the sellar-suprasellar, making it the ideal approach for pediatric infradiaphragmatic craniopharyngiomas. In supradiaphragmatic craniopharyngiomas, the extended EEA provides a clearer and close-up visualization of the tumor-hypothalamus interface, which can grant better results in terms of quality of life. The pediatric skull base anatomy should not represent a contraindication for the endoscopic technique. Larger series encompassing a wider spectrum of pediatric craniopharyngiomas are needed to further support the benefits of this surgical approach.

Endoscopic endo- and extra-orbital corridors for spheno-orbital region: anatomic study with illustrative case.

BACKGROUND AND OBJECTIVE: Management of selected spheno-orbital meningiomas via the endoscopic transorbital route has been reported. Surgical maneuverability in a narrow corridor as that offered by the orbit may be challenging. We investigate the additional use of an extra-orbital (EXO) path to be used in combination with the endo-orbital (EO) corridor. MATERIAL AND METHODS: Three human cadaveric heads (six orbits) were dissected at the Laboratory of Surgical Neuroanatomy at the University of Barcelona. The superior eyelid endoscopic transorbital approach was adopted, introducing surgical instruments via both corridors. Surgical freedom analysis was run to determine directionality of each corridor and to calculate the surgical maneuverability related to three anatomic targets: superior orbital fissure (SOF), foramen rotundum (FR), and foramen ovale (FO). We also reported of a 37-year-old woman with a spheno-orbital meningioma with hyperostosis of the lateral wall of the right orbit, treated with such combined endo-orbital and extra-orbital endoscopic approach. RESULTS: Combining both endo-orbital and extra-orbital corridors permitted a greater surgical freedom for all the targets compared with the surgical freedom of each corridor alone (EO + EXO to SOF: 3603.8 mm2 ± 2452.5 mm2; EO + EXO to FR: 1533.0 mm2 ± 892.2 mm2; EO + EXO to FO: 1193.9 mm2 ± 782.6 mm2). Analyzing the extra-orbital pathway, our results showed that the greatest surgical freedom was gained in the most medial portion of the considered area, namely the SOF (1180.5 mm2 ± 648.3 mm2). Regarding the surgical case, using both pathways, we gained enough maneuverability to nearly achieve total resection with no postoperative complications. CONCLUSION: An extra-orbital corridor may be useful to increase the instruments' maneuverability, during a pure endoscopic superior eyelid approach, and to reach the most medial portion of the surgical field from a lateral-to-medial trajectory. Further studies are needed to better define the proper indications for such strategy.

Endoscopic transorbital route to the petrous apex: a feasibility anatomic study.

BACKGROUND: While the subtemporal approach represents the surgical module milestone designed to reach the petrous apex, a novel ventral route, which is the superior eyelid endoscopic transorbital approach, has been proposed to access the skull base. Accordingly, we aimed to evaluate the feasibility of this route to the petrous apex, providing a qualitative and quantitative analysis of this relatively novel pathway. METHODS: Five human cadaveric heads were dissected at the Laboratory of Surgical NeuroAnatomy of the University of Barcelona. After proper dissection planning, anterior petrosectomy via the endoscopic transorbital route was performed. Specific quantitative analysis, as well as dedicated three-dimensional reconstruction, was done. RESULTS: Using the endoscopic transorbital approach, it was possible to reach the petrous apex with an average volume bone removal of 1.33 ± 0.21 cm3. Three main intradural spaces were exposed: cerebellopontine angle, middle tentorial incisura, and ventral brainstem. The first one was bounded by the origin of the trigeminal nerve medially and the facial and vestibulocochlear nerves laterally, the second extended from the origin of the oculomotor nerve to the entrance of the trochlear nerve into the tentorium free edge while the ventral brainstem area was hardly accessible through the straight, ventral endoscopic transorbital trajectory. CONCLUSION: This is the first qualitative and quantitative anatomic study concerning details of the lateral aspect of the incisura and ventrolateral posterior fossa reached via the transorbital window. This manuscript is intended as a feasibility anatomic study, and further clinical contributions are mandatory to confirm the effectiveness of this approach, defining its possible role in the neurosurgical armamentarium.

Characteristics of meningitis following transsphenoidal endoscopic surgery: a case series and a systematic literature review.

BACKGROUND: Meningitis occurs in 0.8-1.5% of patients undergoing neurosurgery. The aim of the study was to evaluate the characteristics of meningitis after endoscopic endonasal transsphenoidal surgery (EETS) comparing the findings retrieved to those highlighted by literature search. MATERIALS AND METHODS: Patients treated by EETS during an 18-year period in the Department of Neurosurgery of 'Federico II' University of Naples were evaluated and included in the study if they fulfilled criteria for meningitis. Epidemiological, demographic, laboratory, and microbiological findings were evaluated. A literature research according to PRISMA methodology completed the study. RESULTS: EETS was performed on 1450 patients, 8 of them (0.6%) had meningitis [median age 46 years (range 33-73)]. Endoscopic surgery was performed 1-15 days (median 4 days) before diagnosis. Meningeal signs were always present. CSF examination revealed elevated cells [median 501 cells/µL (range 30-5728)], high protein [median 445 mg/dL (range 230-1210)], and low glucose [median 10 mg/dL (range 1-39)]. CSF culture revealed Gram-negative bacteria in four cases (Klebsiella pneumoniae, Escherichia coli, Alcaligenes spp., and Haemophilus influenzae), Streptococcus pneumoniae in two cases, Aspergillus fumigatus in one case. An abscess occupying the surgical site was observed in two cases. Six cases reported a favorable outcome; two died. Incidence of meningitis approached to 2%, as assessed by the literature search. CONCLUSIONS: Incidence of meningitis after EETS is low despite endoscope goes through non-sterile structures; microorganisms retrieved are those present within sinus microenvironment. Meningitis must be suspected in patients with persistent fever and impaired conscience status after EETS.

Atypical pituitary adenomas: clinical characteristics and role of ki-67 and p53 in prognostic and therapeutic evaluation. A series of 50 patients.

The aim of the study was to assess incidence rate, hormonal activity, and local invasiveness and evaluate outcomes of so-diagnosed atypical pituitary adenomas that underwent endoscopic endonasal surgery at the Division of Neurosurgery of Università degli Studi di Napoli Federico II. According to the 2004 WHO classification, atypical pituitary adenomas are defined by an invasive growth, Ki-67/MIB-1 proliferative index greater than 3 %, high p53 immunoreactivity, and increased mitotic activity. A retrospective analysis of a series of 434 pituitary adenomas that underwent endoscopic endonasal surgery at our department between March 2007 and February 2013 was performed. Fifty adenomas (11.5 %) met the criteria of diagnosis of atypical lesions; 10 (21.6 %) of the 50 patients were recurrent tumors with a previous transsphenoidal surgery. Forty-one (82 %) were macroadenomas, and 21/50 (42 %) showed a clear invasion of the cavernous sinus. Histotype of atypical adenomas figured out to be nonfunctioning in 23 cases (46 %), PRL secreting in 10 cases (20 %), ACTH secreting and GH secreting each apart in 8 patients (16 %), and in a single case a GH/PRL secreting adenoma (2 %). The Ki-67 labeling index ranged from 3.5 to 22.5 % (mean 5.6 %). Tumor recurrence was observed in six cases (12 %) after a mean time of 18 months (range 9-24 months). Mean follow-up was 36.5 months (range 2-80 months). Atypical pituitary adenomas account for ca. 10 % of all pituitary adenomas; these lesions have peculiar features. It should be considered that a strong immunopositivity of p53 and higher Ki-67 LI could predict an increased risk of tumor recurrence, but more studies and larger series are expected to confirm and enlarge the diagnostic and therapeutic management process of these lesions.

Tips and Tricks for Anterior Cranial Base Reconstruction.

Reconstruction procedures come last in skull base surgery, but they are not the least important phase-rather, reconstruction is one of the most important steps required to prevent complications. In our opinion, there are three general principles upon which a good reconstruction of the skull base stand: (1) anatomo-surgical knowledge; (2) approach/route selection; and (3) the cooperation of the skull base surgical team. In general, three major complications may occur when a good skull base reconstruction has not been achieved, i.e., cerebrospinal fluid (CSF) leak, pneumoencephalus, and infection. Reconstruction of skull base defects requires a thorough knowledge of surgical anatomy, disease, and patient risk factors. Various reconstruction techniques are available, from free tissue grafting to vascularized flaps. Possible complications that can occur after these procedures need to be considered.The reconstruction phase of the surgical procedure is a fundamental step in any surgical approach and it must not be ignored.

The role of inferior petrosal sinus sampling in ACTH-dependent Cushing's syndrome: review and joint opinion statement by members of the Italian Society for Endocrinology, Italian Society for Neurosurgery, and Italian Society for Neuroradiology.

In the management of adrenocorticotropic hormone (ACTH)-dependent Cushing's syndrome, inferior petrosal sinus sampling (IPSS) provides information for the endocrinologist, the neurosurgeon, and the neuroradiologist. To the endocrinologist who performs the etiological diagnosis, results of IPSS confirm or exclude the diagnosis of Cushing's disease with 80%-100% sensitivity and over 95% specificity. Baseline central-peripheral gradients have suboptimal accuracy, and stimulation with corticotropin-releasing hormone (CRH), possibly desmopressin, has to be performed. The rationale for the use of IPSS in this context depends on other diagnostic means, taking availability of CRH and reliability of dynamic testing and pituitary imaging into account. As regards the other specialists, the neuroradiologist may collate results of IPSS with findings at imaging, while IPSS may prove useful to the neurosurgeon to chart a surgical course. The present review illustrates the current standpoint of these 3 specialists on the role of IPSS.