Endoscopic Supraorbital Translaminar Approach.

Surgical selection for third ventricle tumors demands meticulous planning, given the complex anatomic milieu. Traditional open microsurgical approaches may be limited in their access to certain tumors, prompting the exploration of alternative techniques. The endoscopic supraorbital translaminar approach (ESOTLA) has emerged as a promising alternative for managing these tumors. By combining a minimally invasive keyhole approach with endoscopic visualization, the ESOTLA provides enhanced illumination and a wider angle of view within the third ventricle. This unique advantage allows for improved access to retrochiasmatic tumors and reduces the need for frontal lobe and optic chiasm retraction required of microscopic techniques, decreasing the risk of neurocognitive and visual deficits. Complications related to the ESOTLA are rare and primarily pertain to cosmetic issues and potential compromise of the hypothalamus or optic apparatus, which can be minimized through careful subarachnoid dissection. This chapter offers a comprehensive description of the technical aspects of the ESOTLA, providing insights into its application, advantages, and potential limitations. Additionally, a case description highlights the successful surgical extirpation of an intraventricular papillary craniopharyngioma via the ESOTLA followed by targeted therapy. To better illustrate the stepwise dissection through this novel approach, a series of cadaveric and intraoperative photographs are included.

Endoscopic Anatomy of the Skull Base.

Presently, endoscopic skull base surgery has undergone significant advancements since its inception over two decades ago. Nevertheless, it is imperative to underscore that the fundamental basis of all surgical procedures lies in the meticulous understanding of anatomy, with particular emphasis on the ventral anatomy. This facet has recently garnered increased attention.Following the advancements in endoscopic skull base surgery techniques, this chapter will concentrate on the pertinent anatomical considerations that serve as key foundations for successful procedures. These considerations are categorized into two planes: the sagittal plane and the coronal plane.The sagittal plane is further subdivided into five distinct approaches, namely,(1) the transcribriform approach, (2) the transplanum approach, (3) the transsellar approach, (4) the transclival approach, and (5) the transodontoid approach.On the other hand, the coronal plane is delineated into seven specific zones to facilitate comprehension and potential applications: (1) the petrous apex approach, (2) the intrapetrous approach, (3) the suprapetrous approach, (4) the cavernous sinus approach, (5) the infratemporal approach, (6) the medial condyle approach, and (7) the jugular foramen approach.By organizing the anatomical aspects in this systematic manner, the information provided becomes more accessible, fostering a comprehensive understanding of the subject matter for potential future application.

Systematic reviews and meta-analyses in neurosurgery part I: interpreting and critically appraising as a guide for clinical practice.

Neurosurgeons are inundated with the Herculean task to keep abreast with the rapid pace at which clinical research is proliferating. Systematic reviews and meta-analyses (SRMAs) have consequently surged in popularity because when executed properly, they constitute the highest level of evidence, and may save busy neurosurgeons many hours of combing the literature. Well-executed SRMAs may prove instructive for clinical practice, but poorly conducted reviews sow confusion and may potentially cause harm. Unfortunately, many SRMAs within neurosurgery are relatively lackluster in methodological rigor. When neurosurgeons apply the results of an SRMA to patient care, they should start by evaluating the extent to which the employed methods have likely protected against misleading results. The present article aims to educate the reader about how to interpret an SRMA, to assess the potential relevance of its results in the special context of the neurosurgical patient population.

Clinical characteristics and outcomes after trigeminal schwannoma resection: a multi-institutional experience.

Given their rarity, the clinical course of patients undergoing trigeminal schwannoma (TS) resection remains understudied. The objective of this study is to describe clinical characteristics and outcomes in patients undergoing surgical resection for TS in a multi-institutional cohort. This is a retrospective study of patients undergoing TS resection at two institutions between 2004 and 2022. Patient, radiographic, and clinical characteristics were reviewed and analyzed with standard statistical methods. Thirty patients were included. The median patient age was 43 (IQR: 35-52) years, and 14 (47%) patients were female. Median clinical and radiographic follow-ups were 43 (IQR: 20-81) and 47 (IQR: 27-97) months respectively. The most common presenting symptoms were trigeminal hypesthesia (57%) and headaches (30%), diplopia (30%), and ataxia/cerebellar signs (30%). The median maximum tumor diameter was 3.3 (IQR: 2.5-5.4) cm. Most tumors were Samii type C (50%) and mixed cystic-solid (63%). Surgical approaches included endoscopic endonasal (33%), supratentorial (30%), combined/staged (20%), infratentorial (10%), and anterior petrosal (7%) approaches. Gross-total resection was achieved in 16 (53%) patients. Radiographic tumor recurrence was noted in four patients at a median of 79 (range 5-152) months. Twenty-six (87%) patients reported improvements in at least one symptom by last follow-up. The most common perioperative complication was new cranial nerve deficit, with 17% of patients having a transient deficit and 10% having a permanent cranial nerve deficit. Surgical resection of TS showed good progression-free survival and symptom improvement, but was associated with cranial nerve deficits.

Endoscopic precaruncular medial transorbital and endonasal multiport approaches to the contralateral skull base: a clinicoanatomical study.

OBJECTIVE: Minimally invasive endoscopic endonasal multiport approaches create additional visualization angles to treat skull base pathologies. The sublabial contralateral transmaxillary (CTM) approach and superior eyelid lateral transorbital approach, frequently used nowadays, have been referred to as the "third port" when used alongside the endoscopic endonasal approach (EEA). The endoscopic precaruncular contralateral medial transorbital (cMTO) corridor, on the other hand, is an underrecognized but unique port that has been used to repair CSF rhinorrhea originating from the lateral sphenoid sinus recess. However, no anatomical feasibility studies or clinical experience exists to assess its benefits and demonstrate its potential role in multiport endoscopic access to the other contralateral skull base areas. In this study, the authors explored the application and potential utility of multiport EEA combined with the endoscopic cMTO approach (EEA/cMTO) to three target areas of the contralateral skull base: lateral recess of sphenoid sinus (LRSS), petrous apex (PA) and petroclival region, and retrocarotid clinoidocavernous space (CCS). METHODS: Ten cadaveric specimens (20 sides) were dissected bilaterally under stereotactic navigation guidance to access contralateral LRSS via EEA/cMTO. The PA and petroclival region and retrocarotid CCS were exposed via EEA alone, EEA/cMTO, and EEA combined with the sublabial CTM approach (EEA/CTM). Qualitative and quantitative assessments, including working distance and visualization angle to the PA, were recorded. Clinical application of EEA/cMTO is demonstrated in a lateral sphenoid sinus CSF leak repair. RESULTS: During the qualitative assessment, multiport EEA/cMTO provides superior visualization from a high vantage point and better instrument maneuverability than multiport EEA/CTM for the PA and retrocarotid CCS, while maintaining a similar lateral trajectory. The cMTO approach has significantly shorter working distances to all three target areas compared with the CTM approach and EEA. The mean distances to the LRSS, PA, and retrocarotid CCS were 50.69 ± 4.28 mm (p < 0.05), 67.11 ± 5.05 mm (p < 0.001), and 50.32 ± 3.6 mm (p < 0.001), respectively. The mean visualization angles to the PA obtained by multiport EEA/cMTO and EEA/CTM were 28.4° ± 3.27° and 24.42° ± 5.02° (p < 0.005), respectively. CONCLUSIONS: Multiport EEA/cMTO to the contralateral LRSS offers the advantage of preserving the pterygopalatine fossa contents and the vidian nerve, which are frequently sacrificed during a transpterygoid approach. This approach also offers superior visualization and better instrument maneuverability compared with EEA/CTM for targeting the petroclival region and retrocarotid CCS.

Customized ventral bony and dural opening in the transplanum/transtuberculum and transclival variants of extended endoscopic endonasal approach to suprasellar craniopharyngiomas: an approach-based stepwise cadaveric dissection and clinical applicability.

BACKGROUND: Optimal initial exposure through an extended endoscopic endonasal approach (EEA) for suprasellar craniopharyngiomas ensures safe and unrestricted surgical access while avoiding overexposure, which may prolong the procedure and increase neurovascular adverse events. METHOD: Here, the authors outline the surgical nuances of a customized bony and dural opening through the transplanum/transtuberculum and transclival variants of the extended EEA to suprasellar craniopharyngiomas based on the tumor-pituitary stalk relationship. A stepwise cadaveric dissection and intraoperative photographs relevant to the approaches are also provided. CONCLUSION: Safe maximal resection of suprasellar craniopharyngiomas through extended EEAs can be feasibly and safely achieved by implementing of tailored ventral exposure.

Endoscopic endonasal marsupialization of rathke cleft cysts: clinical outcomes and risk factors analysis of visual impairment, pituitary dysfunction, and CSF leak.

OBJECTIVE: This paper assesses the clinical and imaging characteristics, histopathological findings, and treatment outcomes of patients with Rathke's cleft cyst (RCC), as well as identifies potential risk factors for preoperative visual and pituitary dysfunction, intraoperative cerebrospinal fluid (CSF) leak, and recurrence. Through analyzing these factors, the study aims to contribute to the current understanding of the management of RCCs and identify opportunities for improving patient outcomes. METHODS: We performed a retrospective analysis of 45 RCC patients between ages 18-80 treated by Endoscopic Endonasal Approach (EEA) and cyst marsupialization between 2010 and 2022 at a single institution. RESULTS: The median patient age was 34, and 73% were female. The mean follow-up was 70 ± 43 months. Preoperative visual impairment correlated with cyst diameter (OR = 1.41, 95% CI = 1.07 to 1.85, p-value = 0.01) and older age (OR = 1.06, 95% CI = 1.01 to 1.11, p-value = 0.02). Intraoperative CSF leaks were 11 times more likely for cysts ≥ 2 cm (OR = 11.3, 95% CI = 1.25 to 97.37, p-value = 0.03), with the odds of leakage doubling for every 0.1 cm increase in cyst size (OR = 1.41, 95% CI = 1.08 to 1.84, p-value = 0.01). Preoperative RCC appearing hypointense on T1 images demonstrated significantly higher CSF leak rates than hyperintense lesions (OR = 122.88, 95% CI = 1.5 to 10077.54, p-value = 0.03). Preoperative pituitary hypofunction was significantly more likely in patients with the presence of inflammation on histopathology (OR = 20.53, 95% CI = 2.20 to 191.45, p-value = 0.008 ) and T2 hyperintensity on magnetic resonance imaging (MRI) sequences (OR = 23.2, 95% CI = 2.56 to 211.02, p-value = 0.005). Notably, except for the hyperprolactinemia, no postoperative improvement was observed in pituitary function. CONCLUSION: Carefully considering risk factors, surgeons can appropriately counsel patients and deliver expectations for complications and long-term results. In contrast to preoperative visual impairment, preoperative pituitary dysfunction was found to have the least improvement post-surgery. It was the most significant permanent complication, with our data indicating the link to the cyst signal intensity on T2 MR and inflammation on histopathology. Earlier surgical intervention might improve the preservation of pituitary function.

Subfascial dissection and extended temporal muscle detachment for middle fossa approach.

BACKGROUND: The soft tissue dissection for the middle fossa approach requires adequate management of the neuro, vascular, and muscular structures in order to maximize exposure and diminish morbidities. METHODS: An incision anterior to the tragus is performed, extending from the zygomatic process to the superior temporal line. The superior temporal artery is exposed, followed by a subfascial dissection of the frontalis nerve. The temporal muscle is dissected and released from the zygoma. All cranial landmarks are exposed for the 5 × 5 cm temporal fossa craniotomy. CONCLUSION: This novel approach provides a safe and adequate access to perform an extended middle fossa craniotomy.

Intraoperative Electrocochleography in Subjects Affected by Vestibular Schwannoma and Ménière's Disease: Comparison of Results.

OBJECTIVES: Histologic reports of temporal bones of ears with vestibular schwannomas (VSs) have indicated findings of endolymphatic hydrops (ELH) in some cases. The main goal of this investigation was to test ears with VSs to determine if they exhibit electrophysiological characteristics similar to those of ears expected to experience ELH. DESIGN: Fifty-three subjects with surgically confirmed VS aged ≥18 and with normal middle ear status were included in this study. In addition, a second group of adult subjects (n = 24) undergoing labyrinthectomy (n = 6) or endolymphatic sac decompression and shunt (ELS) placement (n = 18) for poorly controlled vestibular symptoms associated with Meniere's disease (MD) participated in this research. Intraoperative electrocochleography (ECochG) from the round window was performed using tone burst stimuli. Audiometric testing and word recognition scores (WRS) were performed preoperatively. ECochG amplitudes, cochlear microphonic/auditory nerve neurophonic (ANN) in the form of the "ongoing" response and summation potential, were analyzed and compared between the two groups of subjects. In addition, to evaluate any effect of auditory nerve function, the auditory nerve score was calculated for each subject. Pure-tone averages were obtained using the average air conduction thresholds at 0.5, 1, and 2 kHz while WRS was assessed using Northwestern University Auditory Test No. 6 word lists. RESULTS: In the VS group the average pure-tone averages and WRS were 59.6 dB HL and 44.8%, respectively, while in the MD group they were 52.3 dB HL and 73.8%. ECochG findings in both groups revealed a reduced trend in amplitude of the ongoing response with increased stimulus frequency. The summation potential amplitudes of subjects with VS were found to be less negative than the MD subjects for nearly all test frequencies. Finally, the VS group exhibited poorer amounts of auditory nerve function compared to the MD group. CONCLUSIONS: The current findings suggest cochlear pathology (e.g., hair cell loss) in both groups but do not support the hypothesis that VSs cause ELH.

Modern endoscopic skull base neurosurgery.

INTRODUCTION: Since the early use of the endoscopic view for treating simple intrasellar pituitary adenomas, the skull base surgery has experienced an unprecedented revolution elevating the treatment of skull base lesions to the next level in proficiency and excellence of care. METHODS: We have reviewed the preclinical and clinical evidence supporting the use of the endoscope in the treatment of skull base lesions. In this article, we aim to discuss and provide a wide view of the current indications and future perspectives of the endoscopic endonasal approaches (EEA) and of the endoscopic transcranial approaches. RESULTS: As in the development of any other technique, EEA have gone through a transformation process from theoretical anatomic models to a pragmatic clinical use. Along the way, EEA have required several modifications, as well as pushbacks in the application of this technique in some indications. This process has resulted in the provision of an additional tool to the current surgical armamentarium that allows the skull base surgeon to face most challenging lesions along the skull base. CONCLUSIONS: The judicious combination of transcranial and endoscopic-transnasal approaches warrants highest chances of achieving satisfactory tumors resection with a reduced risk of complications.

The sellar barrier on preoperative imaging predicts intraoperative cerebrospinal fluid leak: a prospective multicenter cohort study.

BACKGROUND: The type of sellar barrier observed between a pituitary tumor and cerebrospinal fluid (CSF) on preoperative magnetic resonance imaging (MRI) may predict intraoperative CSF leak during endonasal pituitary surgery. This is the first multicentric prospective cohort trial to study the sellar barrier concept and CSF leak rate during endoscopic pituitary surgery. METHODS: This multi-center, international study enrolled patients operated for pituitary adenomas via fully endoscopic endonasal surgery over a period of 4 months. The independent variable was the subtype of sellar barrier observed on preoperative MRI (strong, mixed or weak); the dependent variable was the presence of an intraoperative CSF leak. The primary goal was to determine the association between a particular type of sellar barrier and the risk of intraoperative CSF leak. Appropriate statistical methods were then applied for data analysis. RESULTS: Over the study period, 310 patients underwent endoscopic endonasal surgery for pituitary tumor. Preoperative imaging revealed a weak sellar barrier in 73 (23.55%), a mixed sellar barrier in 75 (24.19%), and a strong sellar barrier in 162 (52.26%) patients. The overall rate of intraoperative CSF leak among all patients was 69 (22.26%). A strong sellar-type barrier was associated with significantly reduced rate of intraoperative CSF leak (RR = 0.08; 95% CI 0.03-0.19; p < 0.0001), while a weak sellar barrier associated with higher rates of CSF leak (RR = 8.54; 95% CI 5.4-13.5; p < 0.0001). CONCLUSIONS: The preoperative MRI of pituitary patients can suggest intraoperative CSF leak rates, utilizing the concept of the sellar barrier. Patients with a weak sellar barrier carry a higher risk for an intraoperative CSF leak, whereas a strong sellar barrier on MRI seems to mitigate intraoperative CSF leak. We propose that preoperatively assessment of the sellar barrier can prepare surgeons for intraoperative CSF leak repair.

Bony landmarks in the endoscopic endonasal transoculomotor approach.

The endoscopic endonasal transoculomotor approach (EETA) has been recently described as a doorway to access the parapeduncular space and treat pituitary adenomas with oculomotor extension. Intraoperative identification of the oculomotor triangle endonasally is challenging and dissection can put the internal carotid artery (ICA) at risk. The aim of the present study is to find reliable landmarks that identify the oculomotor triangle (OCMT) during the EETA and protect the ICA from injury. Several lines were defined for calculations. Among them, one oblique line that extends from the inferior margin of the lateral orbital canal recess to the vidian canal was named the clinoid-to-vidian line (CVL), while a vertical line that extends over the most medial point of the paraclival ICA was titled the sagittal paraclival line (SPL). Anatomic relationships between the OCMT to these lines were assessed in 7 cadaveric heads. The intersecting point between the CVL and SPL is located within 2 mm of the center of the OCMT (mean 0.8 ± 0.5 mm), and 1.1 ± 0.8 mm medially and above the parasellar ICA. CVL and SPL are reliable landmarks during the EETA that can both protect the parasellar ICA and anatomically orientate to the blind spot that corresponds with the OCMT. We recommend starting dissection medial and superior to the CVL-SPL intersecting point, and carry the dissection laterally thereafter to avoid inadvertent injury of the ICA.

Anatomic feasibility of endoscopic endonasal intracranial aneurysm clipping: a systematic review of anatomical studies.

Clinical studies have suggested the endoscopic endonasal approach (EEA) for aneurysm clipping as a feasible way to treat select intracranial aneurysms. Among neurosurgery, there is not a consensus on the utility of EEA aneurysm clipping. This review aims to define the anatomic feasibility of EEA for aneurysm clipping. Two databases (PubMed, Cochrane) were searched for anatomical studies assessing EEA for intracranial aneurysm clipping. Literature review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Quantitative anatomical studies were included. Eleven studies met inclusion criteria. Vascular exposure and clip placement on vessels of interest were possible, although only one study assessed these parameters with physical aneurysm models. Anterior circulation vessels, although accessible in over 90% of specimens, had low successful clipping rates in a small and large aneurysm models. Small and large model posterior circulation aneurysms were more readily clipped. Proximal and distal controls were readily attainable in posterior circulation aneurysms, but not anterior. This current literature review highlights the relevance of anatomical studies in assessing the feasibility of the EEA for clipping intracranial aneurysms. As such, anterior circulation aneurysms are poor candidates for EEA given difficulties in clip placement and obtaining proximal control and distal control in small and large aneurysms. While our results suggest that clipping of posterior circulation aneurysms is feasible from a technical stand of view, further clinical experience is required to assess its feasibility in terms of safety and efficacy, balancing the indications with endovascular treatment options.

Outcome of the surgical decompression for traumatic optic neuropathy: a systematic review and meta-analysis.

There exists a persisting controversy regarding the indications for optic nerve surgical decompression (ONSD) in traumatic optic neuropathy (TON). A meta-analysis is warranted to help guiding therapeutic decisions and address gaps in knowledge. The authors conducted a search of PubMed and MEDLINE electronic databases. Primary endpoint was the improvement in the visual function with ONSD in comparison with the conservative management. Secondary endpoint was visual function improvement when surgery was performed within the first 7 days. A random effects model meta-analysis was conducted. Data from each study were used to generate log odds ratio and 95% confidence intervals, to compare post-operative visual improvement. Nine studies met the inclusion criteria for analysis, comprising 766 patients. Visual improvement occurred in 55% (198/360) of patients treated with ONSD, and in 40% (164/406) of those who underwent conservative treatment. Forest plot revealed significant differences in the visual function improvement among these two groups, although further analysis revealed the studies were heterogeneous (log OR, 0.81; CI, 0.07-1.55; I2, 62.8% p = 0.015). Overall, patients who underwent early surgery had better visual outcomes (log OR, 0.94; CI, 0.29-1.60; I2, 0% p = 0.9). ONSD is an effective technique to improve the outcome in the visual function in patients with TON. A lack of randomized controlled trial-and inherent surgical selection and publication bias-limits direct comparison between surgical decompression and conservative management. Suitably designed prospective cohort studies may be useful in identifying patients more likely to receive benefit from ONSD.

Same viewing angle, minimal craniotomy enlargement, extreme exposure increase: the extended supraorbital eyebrow approach.

The supraorbital eyebrow approach (SEa) has been commonly used as a straightforward route to reach lesions located in the anterior cranial fossa. The reduced surgical exposure provided by this approach limits its applicability. A modification of the SEa, the extended supraorbital eyebrow approach (X-SEa), allows use of the transylvian corridor to approach parasellar lesions, while maintaining most of the aesthetic advantages of the SEa. To quantify the surgical exposure and maneuverability provided by the X-SEa using a cadaveric study. Eleven heads were used to obtain all stereotactic measurements. Surgical exposure and maneuverability were measured by means of the area of exposure and the angles of attack along key representative points in the anterior circulation. The horizontal angle of attack at the middle cerebral artery provided by the X-SEa was larger than that provided by the SEa (32.6 vs 18.4°, p = 0.009). The X-SEa afforded broader vertical angles of attack at all targets in the anterior circulation (p < 0.05). The total area of exposure provided by the X-SEa was significantly larger than that provided by the SEa (1272 vs 978 ± 156 mm2, p = 0.003). The area of exposure in the ipsilateral trigon and in the midline quadrangle was also significantly larger for the X-SEa (paramedian 195 vs 121 mm2, p = 0.01; midline 1310 vs 778 mm2, p = 0.002). The X-SEa increases the exposure and surgical maneuverability along the anterior and middle cranial fossa when compared to the standard SEa.

Safety and effectiveness of endoscopic endonasal intracranial aneurysm clipping: a systematic review.

Once considered far-fetched, endoscopic endonasal clipping (EEC) has been reported as a feasible alternative route for treating intracranial aneurysms located in the midline. Appropriately, debates regarding EEC applicability have arisen amongst the neurosurgical community. We aim to define the safety, effectiveness, and current state-of-art in the use of EEC for intracranial aneurysms. Two databases (PubMed, Cochrane) were queried for intracranial aneurysms that underwent EEC between inception and 2019. Literature review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Data regarding clinical presentation, radiological imaging, and outcome were extracted and analyzed from selected publications. Nine studies with 27 patients (8 males, 19 females), harboring 35 aneurysms (9 ruptured, 26 nonruptured), met the predetermined inclusion criteria. Patient age range is from 34 to 70 (median = 50) years old. Four aneurysms were considered not suitable for EEC during the procedure, and two aneurysms required additional treatment, leading to an overall treatment success (obliteration) rate of 86%. Complications occurred in 7 patients (26%), including CSF leakage in 5 patients (18%) and ischemic complications in 4 (15%). Among the cases reported, complications occurred more frequently in posterior circulation aneurysms in comparison with anterior circulation aneurysms (62.5 vs 10.5%). Ischemic complications occurred in 4 out of 8 posterior circulation aneurysms. Although feasible, EEC is associated with a significant risk of complications, with rates identified that are significantly higher than established open clipping or endovascular management. The current data suggest that transcranial clipping and endovascular occlusion are still the primary indication for treating intracranial aneurysms.

The historical perspective in approaches to the spheno-petro-clival meningiomas.

The current literature regarding surgical treatment for tumors in the sphenopetroclival (SPC) region is merely scarce. Through a comprehensive literature review, we investigated the indications, outcomes, and complications of different surgical approaches to the SPC meningiomas. Given its complicated relationship between these slow-progression tumors and some critical neurovascular structures in the SPC region, surgical treatment of these tumors faces the challenge of achieving a maximal grade of resection, while preserving patient functionality. The development of new surgical techniques and approaches in recent years have permitted the advancement in the treatment of these tumors, with acceptable rates of morbidity and mortality. The choice of a surgical approach as a treatment for the lesion depends mainly on the type of tumor extension, surgeon's preferences, and the displacement of neurovascular structures. Rather than focusing on one single strategy of treatment, the skull-base surgeon should tailor the approach based on the origin and features of the lesion; as well as the peculiarities of the surgical anatomy. This strategy aims to decrease morbidity and to optimize tumor resection and patient quality of life.

The transsylvian corridor through minimally invasive transcranial approaches: a comparative anatomical study.

Minimally invasive transcranial approaches (MITAs) continue to expand in popularity in neurosurgery. Only few MITAs allow sufficient sylvian exposure to enable wide use of the transsylvian corridor. In this study, we aim to compare the transsylvian corridor in two MITAs: the minipterional (MPTa) and the extended supraorbital eyebrow approaches (XSEa). Eight cadaver heads were used to quantify the surgical exposure and maneuverability along the sylvian fissure and the insular lobe provided by the MPTa and the XSEa. Surgical exposure was calculated by means of the exposed length of the sylvian fissure and by the area framed within three extreme points in the insular lobe. Maneuverability was assessed by means of the surgical freedom along the sylvian cistern. XSEa provides twice the frontal exposure and half of the temporal exposure in comparison to the MPTa (p < 0.001 and p = 0.02, respectively). No significant differences were found between the two craniotomies in the length of the exposure of the sylvian fissure, area of insular exposure, or surgical freedom. Both the MPTa and the XSEa afford sufficient grades of exposure along the sylvian fissure and the insular lobe, although the viewing angle is significantly different between the two approaches. Such properties allow either to be used for microsurgery deep within the sylvian cistern. The use of additional corridors, such as the subfrontal route (XSEa) and pretemporal route (MPTa), may influence selection of either the minipterional or the extended supraorbital approaches according to the origin of the surgical pathology addressed.

Management of large intraventricular meningiomas with minimally invasive port technique: a three-case series.

The use of minimally invasive transcranial ports for the resection of deep-seated lesions has been shown to be safe and effective. To date, most of the literature regarding the tubular retractors used in brain surgery is comprised of individual case reports that describe the successful resection of deep-seated lesions such as thalamic pilocytic astrocytomas, colloid cysts in the third ventricle, hematomas, and cavernous angiomas. The authors describe their experience using a tubular retractor system with three different cases involving large intraventricular meningiomas and examine radiographic and patient outcomes. A single-institution, retrospective case series was performed from a skull base database. Patients who underwent resection of intraventricular > 4-cm meningiomas with port technology were identified. The authors reviewed three cases to illustrate the feasibility of minimal access port surgery for the resection of these lesions. Complete resection was achieved in all cases. None of the patients developed permanent neurological deficits. There were no major complications related to surgery and no mortalities. Good clinical and surgical outcomes for atrium meningiomas can be achieved through the minimally invasive port technique and tumor size does not appear to be a limitation.

Surgical anatomy and nuances of the expanded transpterygoid approach to the pterygopalatine fossa and upper parapharyngeal space: a stepwise cadaveric dissection.

BACKGROUND: Superb knowledge of anatomy and techniques to remove the natural barriers preventing full access to the most lateral aspect of the skull base determines the ease of using the transpterygoid approach (ETPA) as the main gateway for all the coronal planes during endonasal surgeries. METHODS: Throughout stepwise image-guided cadaveric dissections, we describe the surgical anatomy and nuances of the ETPA to the pterygopalatine fossa (PPF) and upper parapharyngeal space (UPPS). CONCLUSION: The ETPA represents a lateral extension of the midline corridor and provides a valuable route to access the PPF/UPPS. Major landmarks for this EEA are the infraorbital canal, sphenopalatine foramen, and vidian nerve. It comprises the removal of the palatine bone, posterior wall of the maxillary sinus, and PPF transposition to drill the pterygoid process.