Anterior Interhemispheric Approach Research Articles

A Novel Foley Catheter-Based Brain Retraction Method for the Interhemispheric Approach: Technical Considerations and an Illustrative Video

BACKGROUNDManagement of interhemispheric pathologies requires surgical intervention through a restricted anatomical corridor ensconced within critical cerebral structures. The use of retractors to facilitate operative access may cause damage to cerebral tissue. The development of an innovative retraction technique designed to alleviate cerebral damage in such cases is imperative. OBJECTIVEIn this study, we present a novel and gentle retraction method to facilitate the interhemispheric approach. METHODSWe retrospectively examined data of nine right-handed patients who underwent surgical resection of interhemispheric lesions between 2021 and 2022. All patients underwent surgery for the first time because of this pathology. All operative specimens were histologically confirmed. Clinical characteristics, operative details, and follow-up data were retrospectively analyzed. RESULTSThe new retraction technique was successfully applied to eight tumor patients and one patient with an aneurysm. Eight patients had an anterior interhemispheric approach, and one patient had a posterior interhemispheric approach. Complete surgical excision was achieved in all patients with no postoperative complications. Postoperative Gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) showed no signs of ischemia or contusion. All patients exhibited significant improvements in their symptoms. An illustrative video that elucidates the removal of an interhemispheric epidermoid tumor, employing the anterior ipsilateral interhemispheric approach, featuring the novel retraction method. CONCLUSIONSThe ideal retraction technique during the interhemispheric approach is still a challenge. Our novel retraction technique may help minimize brain parenchymal damage during surgical resection of interhemispheric lesions.

Anatomic Feasibility of a Superficial Temporal Artery to Distal Anterior Cerebral Artery Bypass With a Parietal Branch Interposition Graft: The Superficial Temporal Artery Telescope Bypass.

Revascularizing the postcommunicating segment of the anterior cerebral artery (ACA) using extracranial donor sites requires long interposition grafts. The superficial temporal artery (STA) is frequently used for extracranial-intracranial ACA revascularization. However, the length of either STA branch is not sufficient to reach the ACA with a proper caliber match, so an interposition graft is required. The aim of this study was to evaluate a bypass that uses the 2 main branches of the STA to reach the A3 (pericallosal) segment of the ACA. The frontal and parietal branches of the STA were dissected from 10 cadaveric specimens. The middle internal frontal artery (MIFA) was exposed through an anterior interhemispheric approach. An interposition graft technique was applied using the parietal branch of the STA (pSTA) to connect the frontal branch of the STA (fSTA) with the MIFA. The bypass code is fSTA (E-Ec) pSTA + pSTA (E-Sc) MIFA. Measurements of length and caliber were taken at the anastomotic sites for the distal branches of the STA and the MIFA. The mean (SD) diameter of the MIFA measured 1.4 (0.2) mm, similar to the calibers of the frontal and parietal branches of the STA. The mean (SD) length of the end-to-side STA-MIFA bypass was 145.5 (7.4) mm, and the mean (SD) length of the donor-graft construct measured 204.2 (27.9) mm. This bypass design resulted in a surplus donor graft length of 38%. Using the pSTA as an interposition graft proved to be a successful technique for creating an STA-MIFA bypass, yielding excess donor graft length that facilitated an unstrained bypass construct. This approach offers several advantages, including a single skin incision, ample graft length, caliber compatibility, and a straightforward technical execution.

Anatomy and microsurgical relevance of the outer arachnoid envelope around the olfactory bulb based on endoscopic cadaveric observations.

Surgical approaches to the anterior cranial fossa have great risk of damaging the olfactory tract and bulb. The goal of this study was to describe the outer arachnoid envelope around the olfactory bulb which plays significant role in the approach-related injury of the nerve. A total of 20 fresh human cadaveric heads were examined as a following: 5 cadaveric heads were used to describe a gross overview of the topographic anatomy of the outer arachnoid cover of the olfactory bulb. In 15 cadaveric heads endoscopic surgical approaches were performed to examine the in situ undisrupted anatomy of the outer arachnoid around the olfactory bulb. Four cadaveric heads were used for lateral subfrontal approach, 5 heads for medial subfrontal, 3 heads for median subfrontal approach and 3 heads for anterior interhemispheric approach. The outer arachnoid membrane of the frontal lobe attaches the olfactory bulb strongly to the above lying olfactory sulcus. Only the most rostral portion of the olfactory bulb became slightly detached from the frontal lobe. The outer arachnoid forms a decent protrusion around the tip of the olfactory bulbs. The fila olfactoria have their own outer arachnoid cover as a continuation of the same layer of the olfactory bulb. The effect of brain retraction and manipulation forces on the olfactory bulb and the role of the here located arachnoid membranes were visually analysed and described in detail through the performed four different neurosurgical approaches. The results of our observations provide important anatomical details for the preservation of smelling during neurosurgical procedures.

SURG-25. SURGICAL MORBIDITY IN RELATION TO THE SURGICAL APPROACH FOR OLFACTORY GROOVE MENINGIOMAS—A POOLED ANALYSIS OF 1016 PATIENTS AND PROPOSAL OF A NEW REPORTING SYSTEM

Abstract BACKGROUND There is no consensus regarding whether a frontal or lateral approach is superior for resection of olfactory groove meningiomas (OGM). Objective: 1) To compare surgical approaches for microsurgical resection of OGMs for extent of resection and complication rates. 2) To develop a novel preoperative scoring system to guide choice of approach to decrease surgical morbidity. METHODS A PRISMA-guided pooled analysis of 20,672 surgical reports on OGMs published in the MRI era using search terms such as ‘olfactory groove meningioma’ and ‘surgery’. After title screening and removal of duplicates, we assessed 871 studies on surgical management of OGMs. Following exclusion criteria, 27 studies were chosen for the final pooled cohort analysis of reported patient outcomes. RESULTS The 27 studies identified a total of 1,016 individual patients who underwent open microsurgical resection of OGMs. The approaches used included: pterional/unilateral, bifrontal with variations, and anterior interhemispheric approaches. Across all studies, gross total resection (Simpson Grades I or II) was achieved in 91.4% of cases, and subtotal resection (Grades III and IV) was reported in 8.6% of cases. A cumulative 27% of surgical OGM patients sustained some form of complications. Minor complications 22.2% (CSF leak, seizures, infection, transient cranial nerve palsies, hydrocephalus). Major complications 4.7% (hemorrhage, ischemic infarct, malignant cerebral edema). Correlation between complications and the surgical approach was performed. Among 426 patients who underwent unilateral approaches, 14% experienced minor complications, and 2.1% experienced major complications. The 410 patients who underwent bifrontal approaches, 24.6% experienced minor complications, and 7% experienced major complications. CONCLUSIONS Unilateral approaches appear to have lower complication rates than bilateral approaches, however, the extent of resection is not uniformly reported, making it difficult to identify differences. We herein propose a novel preoperative imaging-based classification scoring system to help select the most suitable surgical approach to achieve lower post-surgical complication rates.

Visual Outcomes and Surgical Approach Selection Focusing on Active Optic Canal Decompression and Maximum Safe Resection for Suprasellar Meningiomas.

The goal of treating patients with suprasellar meningioma is improving or preserving visual function while achieving long-term tumor control. We retrospectively examined patient and tumor characteristics and surgical and visual outcomes in 30 patients with a suprasellar meningioma who underwent resection via an endoscopic endonasal (15 patients), sub-frontal (8 patients), or anterior interhemispheric (7 patients) approach. Approach selection was based on the presence of optic canal invasion, vascular encasement, and tumor extension. Optic canal decompression and exploration were performed as key surgical procedures. Simpson grade 1 to 3 resection was achieved in 80% of cases. Among the 26 patients with pre-existing visual dysfunction, vision at discharge improved in 18 patients (69.2%), remained unchanged in six (23.1%), and deteriorated in two (7.7%). Further gradual visual recovery and/or maintenance of useful vision were also observed during follow-up. We propose an algorithm for selecting the appropriate surgical approach to a suprasellar meningioma based on preoperative radiologic tumor characteristics. The algorithm focuses on effective optic canal decompression and maximum safe resection, possibly contributing to favorable visual outcomes.

Complex arteriovenous malformation of the corpus callosum: Surgical nuances

Introduction: Arteriovenous malformations of the corpus callosum (CC-AVMs) are rare and challenging lesions, accounting for 8–9% of all cerebral AVMs. They are associated with a high risk of recurrent hemorrhage and historically were considered inoperable. This case report describes the successful surgical resection of a high-grade CC-AVM following failed stereotactic radiosurgery. Case Description: A 19-year-old female with an anterior CC-AVM presented with seizures despite being on triple anti-epileptics. The patient had previously undergone conservative management for an intraventricular hemorrhage and stereotactic radiosurgery for the AVM. Pre-operative imaging revealed a 5 cm CC-AVM located at the genu and rostrum of the corpus callosum with intraventricular extension into the third ventricle. The AVM was classified as grade 4 according to the Spetzler-Martin grading system and grade 6 according to the supplementary grading system. The lesion was exposed through the anterior interhemispheric trans-callosal approach, and microsurgical nidal dissection was performed. The large draining vein was identified, coagulated, disconnected, and resected along with the nidus. The total operative time was 12.5 h. Postoperatively, the patient had no neurological deficits and was discharged on day 10. Complete resection was confirmed on postoperative magnetic resonance imaging, and the patient remained seizure-free at the 18-month follow-up visit. Conclusion: This case report demonstrates the feasibility of complete surgical resection for high-grade CC-AVMs that have failed non-surgical therapy. Careful surgical planning and technique can lead to favorable outcomes in these challenging cases.

Microneurosurgical training in the anatomical specimen: A structured plan for endoscopic and microsurgical skull base training during the residency

Background and objectiveThe development of a high level of competence and technical proficiency is one of the main objectives of any neurosurgical training program. Due to many factors, this progressive skill development can be complex during the residency. Despite its high cost and infrastructure requirements, there is renewed interest regarding the role of anatomy labs. The study and dissection of the human cadaver has been the environment where many surgeons have developed the necessary skills for microneurosurgery. We propose a structured endoscopic and microsurgical training dissection program to enable residents to maximize the benefits of their training in the lab. Material and methodsDuring the months of September, October and November 2021, a stay was done at the Microneurosurgery and Skull Base Laboratory of the Miguel Hernández University of Alicante. A total of 2 specimens were used. The first specimen underwent a first endoscopic endonasal dissection phase. After completing the endonasal part, a set of incisions were made to perform the transcranial part. In the second specimen, the transcranial part was performed first, leaving the endonasal endoscopic work for the last phase. ResultsThe results of the dissection program are presented. During the endonasal endoscopic phase, the transsphenoidal approach to the sella was simulated while focusing on the extended approaches in the sagittal plane. During the transcranial phase, right and left anterolateral approaches, a left anterior transcallosal interhemispheric approach, a left transcondylar posterolateral approach and a combined right lateral approach were performed. ConclusionsThe structured dissection of the specimen allowed both endonasal endoscopic and transcranial microsurgical training in the same specimen. This design facilitated the realization of the core skull base approaches in the same specimen. According to our initial experience, we believe that developing common dissection programs is a powerful tool to maximize the results of our residents’ laboratory training.

Anatomical step-by-step dissection of common approaches to the third ventricle for trainees: surgical anatomy of the anterior transcortical and interhemispheric transcallosal approaches, surgical principles, and illustrative pediatric cases.

To create a high-quality, cadaver-based, operatively oriented resource documenting the anterior transcortical and interhemispheric transcallosal approaches as corridors to the third ventricle targeted towards neurosurgical trainees at all levels. Two formalin-fixed, latex-injected specimens were dissected under microscopic magnification and endoscopic-assisted visualization. Dissections of the transcortical and transcallosal craniotomies with transforaminal, transchoroidal, and interforniceal transventricular approaches were performed. The dissections were documented in a stepwise fashion using three-dimensional photographic image acquisition techniques and supplemented with representative cases to highlight pertinent surgical principles. The anterior transcortical and interhemispheric corridors afford excellent access to the anterior two-thirds of the third ventricle with varying risks associated with frontal lobe versus corpus callosum disruption, respectively. The transcortical approach offers a more direct, oblique view of the ipsilateral lateral ventricle, whereas the transcallosal approach readily establishes biventricular access through a paramedian corridor. Once inside the lateral ventricle, intraventricular angled endoscopy further enhances access to the extreme poles of the third ventricle from either open transcranial approach. Subsequent selection of either the transforaminal, transchoroidal, or interforniceal routes can be performed through either craniotomy and is ultimately dependent on individual deep venous anatomy, the epicenter of ventricular pathology, and the concomitant presence of hydrocephalus or embryologic cava. Key steps described include positioning and skin incision; scalp dissection; craniotomy flap elevation; durotomy; transcortical versus interhemispheric dissection with callosotomy; the aforementioned transventricular routes; and their relevant intraventricular landmarks. Approaches to the ventricular system for maximal safe resection of pediatric brain tumors are challenging to master yet represent foundational cranial surgical techniques. We present a comprehensive operatively oriented guide for neurosurgery residents that combines stepwise open and endoscopic cadaveric dissections with representative case studies to optimize familiarity with third ventricle approaches, mastery of relevant microsurgical anatomy, and preparation for operating room participation.

Entrenamiento microneuroquirúrgico en el espécimen anatómico. Propuesta de un plan estructurado de disección endoscópica y microquirúrgica basicraneal durante la residencia

Background and objectiveThe development of a high level of competence and technical proficiency is one of the main objectives of any neurosurgical training program. Due to many factors, this progressive skill development can be complex during the residency. Despite its high cost and infrastructure requirements, there is renewed interest regarding the role of anatomy labs. The study and dissection of the human cadaver has been the environment where many surgeons have developed the necessary skills for microneurosurgery. We propose a structured endoscopic and microsurgical training dissection program to enable residents to maximize the benefits of their training in the lab. Material and methodsDuring the months of September, October and November 2021, a stay was done at the Microneurosurgery and Skull Base Laboratory of the Miguel Hernández University of Alicante. A total of 2 specimens were used. The first specimen underwent a first endoscopic endonasal dissection phase. After completing the endonasal part, a set of incisions were made to perform the transcranial part. In the second specimen, the transcranial part was performed first, leaving the endonasal endoscopic work for the last phase. ResultsThe results of the dissection program are presented. During the endonasal endoscopic phase, the transsphenoidal approach to the sella was simulated while focusing on the extended approaches in the sagittal plane. During the transcranial phase, right and left anterolateral approaches, a left anterior transcallosal interhemispheric approach, a left transcondylar posterolateral approach and a combined right lateral approach were performed. ConclusionsThe structured dissection of the specimen allowed both endonasal endoscopic and transcranial microsurgical training in the same specimen. This design facilitated the realization of the core skull base approaches in the same specimen. According to our initial experience, we believe that developing common dissection programs is a powerful tool to maximize the results of our residents’ laboratory training.

A giant A4-A5 distal anterior cerebral artery aneurysm treated with microsurgical clip reconstruction

Background. Aneurysms of the distal anterior cerebral artery (DACA) are uncommon; they often form near the pericallosal-callosomarginal junction and are typically small. To our knowledge, giant DACA aneurysms developing from the more distant parts of the anterior cerebral artery (ACA), A4-5, have been described only once in the literature. Case description. A 66-year-old gentleman reported with a brief loss of consciousness followed by weakness in his right lower leg. The patient was admitted with a Glasgow Coma Score (GCS) of 15. A computed tomography (CT) scan of the head revealed a left hyperdense mass in the frontal parasagittal supracallosal region. Contrast MRI revealed a heterogeneously enhancing mass measuring 35x30x25 mm. CT angiography (CTA) revealed a small saccular aneurysm on the posteromedial aspect of the mass, perpendicular to the vertical plane of the coronal suture, corresponding to the A4-A5 junction of the left ACA. Through a left paramedian craniotomy, a modified anterior interhemispheric approach that was more posterior than the conventional projection was performed. A giant partially thrombosed was found. The aneurysm was resected, and the neck was reconstructed using four clips placed on top of them to enhance the clipping force over any remaining thrombus. The patient recovered as expected and was neurologically intact three months later. Conclusion. Giant distal anterior cerebral artery (DACA) aneurysms found in the A4-A5 segment represent a pathologically uncommon phenomenon. Due to the rarity of giant aneurysms at this location, their reporting is important to inform meticulous pre-operative planning.

Surgical Morbidity in Relation to the Surgical Approach for Olfactory Groove Meningiomas—A Pooled Analysis of 1016 Patients and Proposal of a New Reporting System

Background: There is currently no consensus in the field regarding whether a frontal or lateral approach is superior for microsurgical resection of olfactory groove meningiomas (OGM). Due to the lack of uniformity in classifying lesions and inherent differences in reporting outcomes after varying operative approaches, the best practice for approaching these lesions is yet to be determined. Objective: This study aimed to assess various surgical approaches undertaken for OGMs, investigate procedural aspects influencing the extent of resection, and analyze the respective complication rate associated with each approach. We performed a comprehensive literature review of presenting signs and symptoms in OGM patients, their surgical management, and the reported surgical outcomes. To address the lack of uniform data reporting across studies and to take more recent translational studies into account, we developed a new classification system for OGMs that can remedy the existing deficiencies in comparability of reporting. Methods: We conducted a PRISMA-guided literature search for surgical reports on OGMs published in the MRI era using broad search terms such as ‘olfactory groove meningioma’ and ‘surgery’, which yielded 20,672 results. After title screening and removal of duplicates, we assessed 871 studies on the specific surgical management of olfactory groove meningiomas. Following the application of exclusion criteria and abstract screening, a set of 27 studies was chosen for the final analysis of a pooled cohort of these reported patient outcomes. Results: The final twenty-seven studies included in our in-depth analysis identified a total of 1016 individual patients who underwent open microsurgical resection of OGMs. The approaches used included: pterional/unilateral, bifrontal with variations, and anterior interhemispheric approaches. Across all studies, gross total resection (Simpson Grades I or II) was achieved in 91.4% of cases, and subtotal resection (Grades III and IV) was reported in 8.6% of cases. A cumulative twenty-seven percent of surgical OGM patients sustained some form of complications. Minor issues accounted for 22.2% (CSF leak, seizures, infection, transient cranial nerve palsies, hydrocephalus), whereas major issues comprised 4.7% (hemorrhage, ischemic infarct, malignant cerebral edema). We then examined the correlation between these complications and the surgical approach chosen. Among pooled cohort of 426 patients who underwent unilateral approaches, 14% experienced minor complications, and 2.1% experienced major complications. For the mixed cohort of 410 patients who underwent bifrontal approaches, 24.6% experienced minor complications, and 7% experienced major complications. Conclusions: Unilateral approaches appear to have lower complication rates for the resection of OGMs compared to bilateral approaches. However, the extent of resection is not uniformly reported, making it difficult to identify differences. The use of an improved preoperative classification and scoring system can help establish a more coherent system to select the most suitable approach and to uniformly report surgical outcomes, such as EOR and complication rates specific to a given OGM and its surgical approach.

Pterional versus anterior interhemispheric approach in anterior skull base meningiomas: A comparative study

IntroductionThe pterional approach and anterior interhemispheric approach are both valid surgical routes for the treatment of anterior skull base meningiomas. Comparative studies of these two surgical routes are not yet reported in the literature. Research questionThis retrospective study aims to compare the surgical outcome of both approaches, pros, and cons as well as potential postoperative complications. Materials and methodsIn this retrospective study the following variables were evaluated: age, sex, meningioma location, symptoms, post-surgical complications, Simpson grade, follow-up/Outcome (maximum six months), hospital stay (days), Intraoperative time (minutes), intra-operative blood loss (mL). ResultsThis retrospective study included a total of 22 patients (18 females and 4 males) with a female/male ratio of 4,5/1. The mean age was 59,5 ± 12,59 years. In 13 patients (59%) an anterior interhemispheric approach was performed; in 9 (41%) patients an extended pterional approach. Comparing the two surgical techniques operative time it was found a significant difference between the two approaches (p = 0,03), and a significant difference (p = 0,016) was found in blood losses during surgical procedures: a lower operative time with a higher blood loss was found performing the anterior interhemispheric approach. Discussion and conclusionThe pterional approach and anterior interhemispheric approach are two possible surgical options for the treatment of anterior skull base meningiomas. Both approaches have achieved optimal results, with total tumor resection in most patients and a low complication rate, and that the best approach depends mainly on the experience of the surgeons. A larger cohort of patients with a longer follow-up is needed to propose an algorithm to select the most suitable surgical route for surgical resection, thus reducing the risks.

Cavernous Malformations: What They Have Taught Us.

Cavernous Malformations: What They Have Taught Us.

Anterior Inter-hemispheric Transcallosal Approach for Resection of Colloid Cyst: A Video Abstract

Abstract Background Although histologically benign, colloid cysts have been an entity of interest to neurosurgeons due to the wide array of possible presentations ranging from asymptomatic to high ICP symptoms to sudden death. It is estimated that colloid cysts represent 0.3 to 2% of all brain tumors.1 As they are typically located in the third ventricle, multiple approaches have been adapted and developed for the maximum resection with the least complications given the sensitive anatomy in the area.1 2 The interhemispheric transcallosal approach can be safely performed to fully resect a third ventricle colloid cyst with close to zero recurrence rate and minimal to none permanent deficits.3 This video is an educational illustration of the surgical technique and the related anatomy for the interhemispheric transcallosal approach and how to provide best chances of a benign postoperative course. Case Description In this surgical video, we present a case of a 20-year-old male, a known case of hypertension and un-controlled diabetes type-1, presented to our hospital with on and off headache, dizziness, and diplopia that gradually progressed. His neurological exam was unremarkable including memory function. CT and MRI scans demonstrated a rounded sharply demarcated lesion at the at the roof of the third ventricle, measuring 1 × 1 cm in size. The patient underwent an anterior inter-hemispheric transcallosal approach, with gross total resection of the cyst. In the follow-up office visit, the patient headache has resolved, and he had no seizures with preserved memory functions. Conclusion When removal of the colloid cyst is indicated, the interhemispheric transcallosal approach can be performed safely with gross total resection and minimal neurological deficit. This is a surgical demonstration of the transcallosal approach showcasing the surgical corridors and related anatomy.

Commentary: Step-by-Step Guide on How to Make a 2-Dimensional Operative Neurosurgical Video: Microsurgical Resection of Right Lateral Ventricle Subependymoma by an Anterior Interhemispheric Transcallosal Approach.

Research Department, Association of Future African Neurosurgeons, Yaounde, Cameroon Correspondence: Ulrick Sidney Kanmounye, MD, Research Department, Association of Future African Neurosurgeons, Immeuble Nziko, Rue Marie Gocker, PO Box 419, Yaounde, Cameroon. Email: [email protected] Twitter: @ulricksidney

Step-by-Step Guide on How to Make a 2-Dimensional Operative Neurosurgical Video: Microsurgical Resection of a Right Lateral Ventricle Subependymoma by an Anterior Interhemispheric Transcallosal Approach.

Digital video recordings are increasingly used across various medical and surgical disciplines with advances in computer hardware and software technologies. The creation of high-quality surgical video footage requires a basic understanding of key technical considerations, together with creativity and sound aesthetic judgment. Online operative videos have become a core resource within neurosurgical education. To provide a step-by-step description for making operative videos using a video from a real case as an example. We recorded an operative video of the microsurgical resection of a right lateral ventricle subependymoma performed by an anterior interhemispheric transcallosal approach. The patient consented to surgical resection of the subependymoma and to publication of this operative video. With the video, we explain the step-by-step process the authors used for developing the raw video into a publishable surgical video. The patient depicted in our video tolerated the surgery well and made a complete recovery. The final video produced from the surgery illustrated elements that Operative Neurosurgery, Neurosurgery, and other journals require in surgical videos. Although more than 1200 peer-reviewed (PubMed) neurosurgical operative videos have been published so far, there has not been a single publication that describes the step-by-step process of producing an operative video. To the best of our knowledge, this is the first published detailed description of editing of an educational operative video in neurosurgery and the first video case report of a microsurgical resection of subependymoma of the lateral ventricle in the peer-reviewed English literature.

The Extreme Anterior Interhemispheric Transcallosal Approach for Pure Aqueduct Tumors: An Anatomical Study.

The cerebral aqueduct is a deep structure located in the diencephalon. It is part of the ventricular system and connects the third and fourth ventricles. The aqueduct has three portions: superior, medial, and inferior. Pure aqueduct tumors occur in the superior portion, and lesions located within the aqueduct are difficult to remove through conventional approaches. Most aqueduct tumors are biopsied and accompanying hydrocephalus is addressed through an endoscopic third ventriculostomy (ETV). The extreme anterior interhemispheric transcallosal approach makes use of a natural corridor to remove aqueduct lesions. Herein, we describe the detailed anatomy of this approach for resecting pure aqueduct tumors in the superior portion of the aqueduct. We aimed to show the normal anatomy of the cerebral aqueduct and the feasibility of the approach to remove tumors within the aqueduct. Ten human brain hemispheres and one cadaveric head were dissected under an operative microscope with 6x to 40x magnification. The cerebral aqueduct anatomy was delineated along with the relationship to nearby structures in the extreme anterior interhemispheric transcallosal approach. We described the anatomy of the cerebral aqueduct within the brain and showed that, with the proper angle for the extreme anterior interhemispheric transcallosal approach, lesions in the cerebral aqueduct can be reached in a single session without damaging periventricular structures. The extreme anterior interhemispheric transcallosal approach provides a direct corridor to the cerebral aqueduct and, thus, is feasible for resecting pure aqueduct tumors in an already dilated intraventricular foramen.

Anterior interhemispheric approach for anterior fossa dural arteriovenous fistulas.

Anterior fossa dural arteriovenous fistulas (AF-DAVF) usually display a cortical venous drainage and are therefore at risk for rupture. Microsurgery is traditionally considered in many centers as the first-line treatment since endovascular treatment (EVT) entails a lower cure rate and significant ophthalmic risks. The anterior interhemispheric approach (AIA), originally described by Mayfrank in 1996, seems to offer the effectiveness of microsurgery while limiting the risks related to subfrontal craniotomy. The objective of this study was to analyze the surgical outcomes of patients who underwent this surgical approach for the treatment of AF-DAVF. We hereby describe our 10years' experience of patients treated for an AF-DAVF with this technique in our institution and retrospectively analyzed our results. In addition, we describe our operative technique and its specificities. Eleven patients with AF-DAVF were included in our study. The definitive cure of the fistula was confirmed in all cases with postoperative cerebral angiography. All patients had a good neurological outcome and no major complication occurred. Brain retractors were never used during surgery, the frontal sinus was never opened neither, and anosmia was never observed after surgery. Anterior interhemispheric approach seems to be safe and effective to treat AF-DAVF with lower risks than other surgical approaches. This technique could be more widely considered when facing such midline vascular lesion.

Development and Validation of Predicting Nomograms for Craniopharyngioma: A Retrospective, Multiple-Center, Cohort Study.

Craniopharyngiomas (CPs) are benign tumors arising from the sellar region. However, little is known about their clinical features and long-term recurrence due to low morbidity and the lack of large cohort studies. Thus, we aimed to develop nomograms to accurately predict the extent of resection and tumor recurrence using clinical parameters. A total of 545 patients diagnosed with CP between 2009 and 2019 were examined: 381 in the development cohort and 164 in the validation cohort. Least absolute shrinkage and selection operator (LASSO) and Cox regression analyses were performed to establish two nomograms. Receiver operating characteristic (ROC) curves, calibration curves, decision curve analysis (DCA) and Kaplan-Meier (KM) curves were used to evaluate their predictive performance and discriminative power, respectively, in the two cohorts. In addition, the EORTC QLQ-BN20 questionnaire was used to assess neuropsychological status in the follow-up. In the development cohort, the area under the curve (AUC) and C-index were 0.760 and 0.758, respectively, for predicting the extent of resection and 0.78 and 0.75, respectively, for predicting 3-year progression-free survival (PFS) and 5-year PFS. Additionally, the model had a predictive accuracy of 0.785. Both nomograms showed acceptable discrimination in the two cohorts. Moreover, DCA demonstrated excellent clinical benefits from the two nomograms. Finally, participants were classified into two distinct risk groups according to the risk score, and an online calculator was created for convenient clinical use. During long term follow-up, hypothyroidism (77.61%) and hypocortisolism (76.70%) were the most common endocrine dysfunction after surgery and significant deficits were observed concerning visual disorder, motor dysfunction and seizures in the recurrent groups. In particular, better quality of life was associated with gross total resection (GTR), postoperative radiation, anterior interhemispheric (AI) approach and transsphenoidal approach. To our knowledge, these are the first nomograms based on a very large cohort of patients with CP that show potential benefits for guiding treatment decisions and long-term surveillance. The current study demonstrated the online calculator serve as the practical tool for individual strategies based on the patient’s baseline characteristics to achieve a better prognosis.

Corpus Callosum and Its Connections: A Fiber Dissection Study

We performed a fine white fiber dissection to demonstrate the extensive connections of the corpus callosum. Three formalin-fixed frozen cadaveric human brain specimens were dissected using Klingler's technique. On one half of each hemisphere, the superior connections of the corpus callosum were dissected and in the other half the inferior connections of the corpus callosum were dissected. The mean length of the corpus callosum from the rostrum to the splenium was 7.8 cm. The fibers of the corpus callosum were classified as superior/dorsal radiations, inferior/ventral radiations, anterior radiations, and posterior radiations. The entire transverse length of the dorsal callosal radiation from one hemisphere to the other was 8.1 cm. For anterior interhemispheric approaches, an incision in the anterior part of the body not extending beyond 3.5 cm from the genu was found to be safe with regards to crossing motor fibers. The corpus callosum was found to have intricate connections with all the lobes of the cerebral hemispheres, including the insular region and the limbic and paralimbic areas. Based on the course and traverse of the callosal fibers, a transverse incision in the corpus callosum should be preferred when performing a callosotomy to access intraventricular lesions as this splits the callosal fibers instead of transecting them. The analysis of the course of the callosal radiations enhances understanding of the growth pattern of primary corpus callosal gliomas and helps to design a safe surgical strategy.