The surgical management of anterior communicating artery aneurysms (AcomA) is challenging due to their deep midline position and proximity to complex skull base anatomy. This study compares the pterional craniotomy with the interhemispheric approach based on the specific aneurysm angulation. A total of 129 AcomA cases were analyzed, with 50 undergoing microsurgical clipping via either the pterional or interhemispheric approach. All selected cases had computed tomography-angiography with sagittal imaging slices and 2D-angiography. Using an interactive tool, 14 cases treated via the interhemispheric approach were matched with 14 cases approached pterionally based on clinical and morphological parameters, emphasizing intracranial aneurysm (IA) dome angulation relative to the frontal skull base. Outcomes included IA occlusion, temporary clipping incidence, intraoperative rupture, postoperative strokes, hemorrhages, hydrocephalus, vasospasm, and patient functionality. Matched cohorts had consistent demographics. Both approaches resulted in similar IA occlusion rates, but the interhemispheric approach led to improved clinical outcomes, measured by the modified Rankin Scale. It also had a lower incidence of hydrocephalus and reduced need for permanent ventriculoperitoneal shunt placement. Vasospasms and postoperative infarction rates were comparable between the groups. Our findings suggest potential advantages of the interhemispheric approach in managing AcomA, depending on aneurysm angulation. Despite a small sample size, the results highlight the importance of customized surgical decision-making based on the unique traits of each aneurysm and the surgeon\'s expertise.

BACKGROUND: The transcallosal retroforniceal transchoroidal approach represents an advanced neurosurgical technique that allows access to lesions located within the posterior third ventricle and mesencephalon. It relies on a comprehensive understanding of microsurgical anatomy and embryology, integrating modern neurosurgical operative techniques to minimize retraction and injury to the normal neuronal structures.
METHODS: We report the cases of 2 patients undergoing treatment via this approach, one presenting with a thalamic cavernoma and the other with cystic low-grade glioma of the midbrain.
RESULTS: In these 2 cases, the decision to use the transcallosal approach was mainly due to improved trajectory, gravitational retraction of the hemisphere, and improved delivery of the lesion into the operative field by gravity alone.
CONCLUSIONS: Through a detailed description of the surgical approach and anatomy, we illustrate the feasibility of the transcallosal retroforniceal transchoroidal approach for accessing lesions located deeply in the brain.

Choroid plexus papilloma (CPP) is a rare benign intracranial tumor origin that predominantly manifests in the lateral ventricle in children, accounting for 0.3%-0.6% of all primary intracranial tumors. It is extremely rare to have the CPP in the trigone of the lateral ventricle through the contralateral posterior interhemispheric transfalcine transprecuneus approach (PITTA). Herein, we report this rare case. A 7-year-old girl presented with headache. Magnetic resonance imaging of the brain showed periatrial lesions, and histopathological examination confirmed CPP (WHO grade I). The contralateral PITTA is a safe, effective, reasonable, and appropriate for some lesions in the trigone of the lateral ventricle. It provides a wider surgical angle (especially for the lateral extension) and reduces the risk of disturbance of the optic radiation compared with the conventional approaches. The use of multiple modern neurosurgical techniques, including interventional embolization, intraoperative navigation, microscope, and electrophysiological monitoring, make the procedure much easier and more accurate, and the neuroendoscope adds to the visualization of the microscope and can reduce surgical complications.

OBJECTIVE: To improve postoperative outcome in middle third falcine meningiomas by cortical venous preservation.
BACKGROUND: Falcine meningiomas arise from the falx and do not involve the superior sagittal sinus (SSS). Their complete resection is often associated with the risk of venous infarction in the eloquent cortex due to overlying superficial cortical veins on the tumors.
METHODS: We report one case of middle third falcine meningioma, where we used the posterior interhemispheric corridor for tumor approach.
CONCLUSIONS: Use of the posterior interhemispheric approach, carefully raised bone flap, along with sharp dissection and vein reinforcement using fibrin glue can help to preserve the cortical veins while resecting the falcine meningiomas.

Management 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. In this study, we present a novel and gentle retraction method to facilitate the interhemisferic approach.
We retrospectively examined data of 9 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.
The new retraction technique was successfully applied to 8 tumor patients and 1 patient with an aneurysm. Eight patients had an anterior interhemispheric approach, and 1 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.
The 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.

Giant falcine meningiomas are surgically complex as they are deep in location, concealed by normal brain parenchyma, in close proximity to various neurovascular structures, and frequently involve the falx bilaterally. Although classically accessed using a bifrontal craniotomy and interhemispheric approach, little data exist on alternative operative corridors for these challenging tumors. We evaluated perioperative and long-term outcomes in patients undergoing transcortical resection of giant bilateral falcine meningiomas.
From 2013 to 2022, fourteen patients with giant bilateral falcine meningiomas treated via a transcortical approach at our institution were identified. Perioperative and long-term outcomes were evaluated to determine predictors of adverse events. Corticectomy depth was also analyzed to determine if it correlated with increased postoperative seizure rates.
57.1% of cases were WHO grade 2 meningiomas. Average tumor volume was 77.8 ± 46.5 cm3 and near/gross total resection was achieved in 78.6% of patients. No patient developed a venous infarct or had seizures in the 6 months after surgery. Average corticectomy depth was 0.83 ± 0.71 cm and increasing corticectomy depth did not correlate with higher risk of postoperative seizures (P = 0.44). Increasing extent of tumor resection correlated with lower tumor grade (P = 0.011) and only 1 patient required repeat resection during a median follow-period of 24.9 months.
The transcortical approach is a safe alternative corridor for accessing giant, falcine meningiomas, and postoperative seizures were not found to correlate with increasing corticectomy depth. Further prospective studies are necessary to determine the best approach to these surgically complex lesions.

BACKGROUND: Suprasellar masses commonly include craniopharyngiomas and pituitary adenomas. Suprasellar glioblastoma is exceedingly rare with only a few prior case reports in the literature. Suprasellar glioblastoma can mimic craniopharyngioma or other more common suprasellar etiologies preoperatively.
METHODS: A 65-year-old male with no significant history presented to the emergency department with a subacute decline in mental status. Work-up revealed a large suprasellar mass with extension to the right inferior medial frontal lobe and right lateral ventricle, associated with significant vasogenic edema. The patient underwent an interhemispheric transcallosal approach subtotal resection of the interventricular portion of the mass. Pathological analysis revealed glioblastoma, MGMT partially methylated, with a BRAF V600E mutation.
CONCLUSIONS: Malignant glioblastomas can mimic benign suprasellar masses and should remain on the differential for a diverse set of brain masses with a broad range of radiological and clinical features. For complex cases accessible from the ventricle where the pituitary complex cannot be confidently preserved via a transsphenoidal approach, an interhemispheric approach is also a practical initial surgical option. In addition to providing diagnostic value, molecular profiling may also reveal therapeutically significant gene alterations such as BRAF mutations.

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.

OBJECTIVE: Opening the roof of the interhemispheric microsurgical corridor to access various neurooncological or neurovascular lesions can be demanding because of the multiple bridging veins that drain into the sinus with their highly variable, location-specific anatomy. The objective of this study was to propose a new classification system for these parasagittal bridging veins, which are herein described as being arranged in 3 configurations with 4 drainage routes.
METHODS: Twenty adult cadaveric heads (40 hemispheres) were examined. From this examination, the authors describe 3 types of configurations of the parasagittal bridging veins relative to specific anatomical landmarks (coronal suture, postcentral sulcus) and their drainage routes into the superior sagittal sinus, convexity dura, lacunae, and falx. They also quantify the relative incidence and extension of these anatomical variations and provide several preoperative, postoperative, and microneurosurgical clinical case study examples.
RESULTS: The authors describe 3 anatomical configurations for venous drainage, which improves on the 2 types that have been previously described. In type 1, a single vein joins; in type 2, 2 or more contiguous veins join; and in type 3, a venous complex joins at the same point. Anterior to the coronal suture, the most common configuration was type 1 dural drainage, occurring in 57% of hemispheres. Between the coronal suture and the postcentral sulcus, most veins (including 73% of superior anastomotic veins of Trolard) drain first into a venous lacuna, which are larger and more numerous in this region. Posterior to the postcentral sulcus, the most common drainage route was through the falx.
CONCLUSIONS: The authors propose a systematic classification for the parasagittal venous network. Using anatomical landmarks, they define 3 venous configurations and 4 drainage routes. Analysis of these configurations with respect to surgical routes indicates 2 highly risky interhemispheric surgical fissure routes. The risks are attributable to the presence of large lacunae that receive multiple veins (type 2) or venous complex (type 3) configurations that negatively impact a surgeon\'s working space and degree of movement and thus are predisposed to inadvertent avulsions, bleeding, and venous thrombosis.

Surgical removal of tumors of the atrium is challenging due to their deep location, vascularization, and to their complex three-dimensional relationships with the highly functional white matter fibers of the region. To assess the feasibility and the effectiveness of the ipsilateral interhemispheric transprecuneus approach (IITA) for tumors involving the atrium and the posterior third of the temporal horn, a retrospective chart review of all patients who had undergone a surgical treatment for intraventricular tumors between January 2008 and January 2017 was performed, and the step-by-step approach is described. Ten patients affected by lesions of the atrium of the lateral ventricle underwent surgical treatment, seven of which were approached through the IITA. The mean age was 42.8 years (range 6-63 years). The symptoms presented included severe, drug-resistant headache (90%), lateral homonymous hemianopsia (50%), seizures (30%), and speech disturbances (30%). Histological examinations revealed seven patients with meningioma (70%), one with a metastasis (10%), one with a choroid plexus papilloma (10%) and one with a cavernoma (10%). In all cases, a gross total removal was obtained. All patients had a significant improvement in their headache. Two patients experienced a worsening of the pre-operative visual disturbances, while two patients had a significant improvement. No patients without pre-operative visual disturbances described a post-operative worsening of visual symptoms. The IITA represents a feasible approach for tumors of the atrium. The three-quarter prone position facilitates the enlargement of the interhemispheric fissure by increasing the working angle and facilitating the exposure of the lateral wall of the atrium.