Interhemispheric Approach Research Articles

Suprasellar Tumor-Craniotomy

Surgical procedures for pediatric suprasellar tumors include craniotomy and nasal surgery. Craniotomies are increasingly performed with a microscope, exoscope, and endoscope, while nasal surgery is performed mainly with endoscopes. In some cases, craniotomy and nasal surgery are performed together. This article describes craniotomy. Due to its large surgical field, craniotomy is often chosen for large tumors in the suprasellar region, tumors located above the optic chiasm and optic nerve, tumors extending laterally, and hypervascularized tumors. It is the surgical technique of choice for many neurosurgeons because they are familiar with it. Craniotomies include bilateral frontal and frontotemporal craniotomies. The interhemispheric and subfrontal approaches involve bilateral frontal craniotomy, pterional approach, orbitozygomatic approach, subtemporal approach using temporal-occipital craniotomy, and transpetrosal transtentorial approach using temporal-occipital-suboccipital craniotomy. The approach was selected based on the direction of tumor extension and relationship between the tumor and optic nerve, optic chiasm, and blood vessels. This paper describes the frequently used interhemispheric and pterional approaches based on our experience.

The Ipsilateral Interhemispheric Transprecuneal Approach to the Atrium: Technical Considerations and Clinical Outcome on a Series of 7 Patients.

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.

Distal aneurysm of median artery of the corpus callosum: case report

Background. There are many variations of the developmental pathology of the anterior communicating artery with such forms as aplasia, hypoplasia, duplication, triplication and etc. The presence of the median artery of the corpus callosum is a rare pathology of the anterior part of the circle of Willis and, according to the literature the frequency is 4,5-14,2 %. About 81 % of cases, the occurrence of the median artery of the corpus callosum is combined with the presence of anterior communicating artery trifurcation. The incidence of distal anterior cerebral artery aneurysms has been estimated to be from 1.5 to 9.0 % of all intracranial aneurysms, while the median artery of the corpus callosum is rarely mentioned in the literature, the author of the article did not find cases of descriptions of distal anterior cerebral artery aneurysms in the PubMed. It should be borne in mind that when conducting radiation diagnostics, up to one third of all cases of the median artery of the corpus callosum remain undetected.Aim. To present a clinical case of successful surgical treatment of a distal aneurysm of the median artery of the corpus callosum in a patient K., 39 years old, performed using surgical neuronavigation.Materials and methods. A case report of the successful surgical management of 39-year-old patient with distal aneurysm of the median artery of the corpus callosum at the Sity Clinical Hospital No. 1 named after N.I. Pirogov of Moscow Healthcare Department. The patient had a saccular aneurysm of A2-3 segments of the median artery of the corpus callosum.Results. A microsurgical clipping of the distal aneurysm of the median artery of the corpus callosum using the right interhemispheric approach through the bifrontal craniotomy with a neuronavigational assistance was performed. The selective angiography of the intracranial arteries (10 mo after the clipping) no detected the signs of recanalization of the aneurysm.Conclusion. The deeper placement of the median artery of the corpus callosum (as compared with the anterior cerebral arteries) and the missing of anatomical landmarks complicates the surgical approach to the distal aneurysms of the median artery of the corpus callosum. The instrumentation of neuronavigation made it possible to perform minimal craniotomy and safe encephalotomy of the medial aspects of the frontal lobes (at site of the genu the corpus callosum) and reduce the operating time.

Evaluating diploic vein blood flow using time-resolved whole-head computed tomography angiography and determining the positional relationship between typical craniotomy approaches and diploic veins in patients with meningioma.

Diploic veins may act as collateral venous pathways in cases of meningioma with venous sinus invasion. Diploic vein blood flow should be preoperatively evaluated to consider preserving the veins. In this study, we evaluated the use of time-resolved whole-head computed tomography angiography (4D-CTA)-which is less patient-intensive than digital subtraction angiography (DSA)-for assessing diploic vein blood flow and the positional relationship between typical craniotomy approaches and diploic veins. We retrospectively examined 231 patients who underwent surgery for intracranial meningioma. We performed contrast-enhanced magnetic resonance imaging (MRI) to evaluate diploic vein pathways and compared the visualization rates of diploic vein blood flow assessed using 4D-CTA and DSA. Subsequently, we evaluated the rates of the diploic veins transected during craniotomy by comparing the pre- and postoperative contrast-enhanced MRI. The diagnostic performance of 4D-CTA was assessed in 45 patients. Of the 320 diploic veins identified in these patients, blood flow in 70 (21.9%) diploic veins was identified by 4D-CTA and DSA, and both results were consistent. To assess the transection rates of the diploic veins, 150 patients were included. A trend towards a high transection rate of the diploic vein in the basal interhemispheric, frontotemporal, orbitozygomatic, combined transpetrosal, and convexity craniotomy approaches was observed. In patients with meningiomas, both 4D-CTA and DSA are useful in evaluating diploic vein blood flow. In meningiomas with venous sinus invasion, determining the extent of craniotomy after understanding the pathways and blood flow of diploic veins is recommended.

Preservation of frontal white matter tracts in ventricular surgery: favoring an anterior interhemispheric transcallosal approach vs a transcortical transfrontal transventricular approach.

Secondary to the creation of a surgical corridor and retraction, white matter tracts degenerate, causing long-term scarring with potential neurological consequences. Third and lateral ventricle tumors require surgery that may lead to cognitive impairment. Our objective is to compare the long-term consequences of a transcortical transfrontal approach and an interhemispheric transcallosal approach on corpus callosum and frontal white matter tracts degeneration. Surgical patients with ventricular tumor accessible through both approaches were included and clinico-radiological data were retrospectively analyzed. The primary endpoint was the callosotomy length at 3-month post-operative T1 MRI, corrected by the extension of the tumor and the use of neuronavigation. Secondary outcomes included perioperative criteria such as bleeding, use of retractors and duration, FLAIR hypersignal on 3-month MRI, and re-do surgeries. To assess white matter tract interruption, 3-month FLAIR hypersignal was superposed to a tractography atlas. Seventy patients were included, 57 (81%) in the transfrontal group and 13 (19%) in the interhemispheric group. There was no difference in the mean callosotomy length on 3-month MRI (12.3mm ± 5.60 transfrontal vs 11.7mm ± 3.92 interhemispheric, p = 0.79) on univariate and multivariate analyses. The callosotomy length was inferior by - 3.13mm for tumors located exclusively in the third ventricle (p = 0.016), independent of the approach. Retractors were used more often in transfrontal approaches (60% vs 33%, p < 0.001). The extent of frontal FLAIR hypersignal was higher after transfrontal approach (14.1mm vs 0.525mm, p < 0.001), correlated to the use of retractors (p < 0.05). After the interhemispheric approach, no tract other than corpus callosum was interrupted, whereas, after the transfrontal approach, frontal arcuate fibers and projections from the thalamus were interrupted in all patients, the cingulum in 19 (33%), the superior fronto-occipital fasciculus in 15 (26%), and the superior longitudinal fasciculus in 2 (3%). Transfrontal and interhemispheric approaches to the third and lateral ventricles both lead to the same long-term damage to the corpus callosum, but the transfrontal approach interrupts several white matter tracts essential to cognitive tasks such as attention and planning, even in the non-dominant hemisphere. These results encourage all neurosurgeons to be familiar with both approaches and favor the interhemispheric approach when both can give access to the tumor with a comparable risk. Neuropsychological studies are necessary to correlate these anatomical findings to cognitive outcomes.

In vivo goat brain model for neurosurgical training.

Background: Novice neurosurgeons require neurosurgical technique training, but the current method is demanding and time consuming. Therefore, it is crucial to perform training using an appropriate and informative method. In this report, we describe our attempts to provide training in neurosurgical techniques using goat in vivo brain model and to demonstrate the effectiveness of this model.Methods: Under general anesthesia, the surgery was performed on a male goat in the prone position. A midline liner skin incision was made in the scalp, six burr holes were drilled, a craniectomy was performed, and the dura was incised in an arcuate fashion. We attempted the interhemispheric approach and a retrosigmoid approach.Results: It was confirmed that common neurosurgical approaches are achievable in this model. Furthermore, anatomical structures such as nerves and blood vessels were similar to those of humans. Moreover, the goat brain was similar in color and texture to that of humans.Conclusion: Unlike a cadaver brain, in vivo brain requires hemostasis and careful dissection, which provides the surgeons a realistic experience of actual neurosurgery.

Pediatric pineal region tumors: institutional experience of surgical managements with posterior interhemispheric transtentorial approach.

Resecting pineal region tumors in children is often challenging. Several approaches have been proposed and practiced. A personal series of pediatric pineal region tumors resected through craniotomy with posterior interhemispheric occipital transtentorial (OT) approach are reviewed. We present the surgical techniques, pitfalls, and their results. Eighty patients ranging in age from 3months to 21years old, and treated over 3 decades were reviewed. Hydrocephalus caused the main presenting symptoms and was noted in 74 patients. It was treated prior to the craniotomy for tumor resection with endoscopic third ventriculostomy (ETV) in 33, external ventricular drainage in 26, and precraniotomy shunt in 15. Nine patients had ETV together with endoscopic biopsy. All patients had a parieto-occipital craniotomy in a prone position. Through a tentorial section, a gross total resection of the tumor was attempted except for germinomas. The tumor pathology showed 32 germ cell tumors (GCT), 22 benign astrocytomas, 13 pineal parenchymal tumors, 5 ATRTs, 3 papillary tumors, and 5 others. Of GCTs, 18 were teratomas. The extent of resection consisted of 55 gross total resections, 13 subtotal resections, 10 partial, and 2 biopsies with one postoperative death. Hemiparesis in 2, cerebellar ataxia in another 2, and hemiballismus in 1 were transient and improved over time. One had permanent hemisensory loss and another patient had bilateral oculomotor palsy. Postoperative homonymous hemianopia occurred in 2 patients but subsided over a short period of time. Parinaud's sign was noted in 24 patients, of which 16 were transient. The posterior interhemispheric OT approach provides a safe route and comfortable access to the pineal region inchildren. A great majority of postoperative neurological complications are the results of direct manipulations of the midbrain at tumor resection. Identification and preservation of the tumor-brain interface are of paramount importance. GCTs other than teratomas are treated with neoadjuvant chemotherapy and may eliminate the need for craniotomy. Exophytic midbrain JPAs are amenable to resection.

Endoscopic Contralateral Interhemispheric Transfalcine Keyhole Approach for Large Falcine Meningiomas

Falcine meningioma is usually approached ipsilaterally, and the technique for tumor removal has traditionally been performed under microscopy. We report a surgical procedure for large falcine meningioma by an endoscopic contralateral interhemispheric transfalcine keyhole approach. The study period was from September 2019 to March 2021. Study participants were patients with World Health Organization grade I meningioma showing falx attachment, excluding neurofibromatosis, who underwent initial surgery at our institution. The surgical procedure begins with a small contralateral craniotomy of about 3cm, followed by insertion of an endoscope. The tumor attachment to the falx is excised, exposing the tumor. Internal decompression is performed, and the lesion is dissected from the surrounding brain before removal through the falx. An endoscopic contralateral interhemispheric transfalcine keyhole approach was used to resect 4 cases of large falcine meningioma. The mean operation time was 265minutes (range: 216-294minutes), achieving Simpson grade I removal in all cases. No evidence of cerebral infarction, cerebral edema, or new neurological complaints related to impaired venous return was seen using this surgical method. In the case of falcine meningioma, the endoscopic keyhole contralateral technique allows detachment of the tumor from the falx and safe manipulation in a minor field of view. In addition, because the craniotomy is smaller and the operation time is shorter, this procedure offers a less-invasive approach for the patient. This technique is thus, in our opinion, quite advantageous.

Herophilus-Galen line as a predictor of extent of resection in the occipital interhemispheric transtentorial approach to pineal tumors in children.

The goals of this study were to evaluate the extent of resection (EOR) obtained with an occipital interhemispheric transtentorial approach (OITA) in a series of pediatric patients with pineal region tumors and to define preoperative radiological factors predictive of the EOR. This is a retrospective cohort study of a series of pediatric patients with pineal tumors who underwent surgery through a microsurgical OITA performed by the senior author during the period from January 2006 to January 2020. The tumor volume was measured preoperatively, and then on sagittal midline cuts the authors identified the most cranial point of the torcular Herophili (defined as the "Herophilus point") and the lowest point of the inferior profile of the vein of Galen (defined as the "Galen point"). The line joining these two points (defined as the "Herophilus-Galen line" [H-G line]) was used to identify the "Herophilus-Galen plane" (H-G plane) perpendicular to the sagittal plane. Tumor volumes located below and above this plane were measured. EOR was evaluated by measuring residual tumor volume visible on T1 volumetric injected sequences of immediate postoperative MRI. Thirty patients were selected for study inclusion. The preoperative mean tumor volume was 15.120 cm3 (range 0.129-104.3 cm3). The mean volumes were 2.717 cm3 (range 0-31 cm3) above the H-G plane and 12.40 cm3 (median 5.27 cm3, range 0.12-72.87 cm3) below the H-G plane. Three patients underwent only biopsy. Of the remaining 27 patients, gross-total resection (GTR; 100% tumor volume) was achieved in 20 patients (74%). In the remaining 7 patients, the mean residual tumor volume was 7.3 cm3 (range 0.26-17.88 cm3). In 3 of these patients, GTR was accomplished after further surgical procedures (1 in 2 patients, 3 in 1 patient) for an overall GTR rate of 85.18%. Larger tumor volume was significantly associated with incomplete resection (p < 0.001). A tumor volume ≤ 2 cm3 above the H-G plane (p = 0.003), linear extension ≤ 1 mm above the H-G line, and pineal histology were predictive of GTR at first OITA procedure (p = 0.001). The H-G line is an intuitive, easy-to-use, and reliable indicator of the superior anatomical limit of visibility during the microsurgical OITA. This anatomical landmark may be useful as a predictor of EOR for pineal tumors performed through this approach. The main limitations of this study are the small number of patients and the exclusively pediatric age of the patient population.

Occipital Interhemispheric Transtentorial Approach for Tumors of Posterior Third Ventricular Region: Review of Surgical Results.

Controversies exist regarding the ideal surgical approach for tumors in posterior third ventricular region (PTV). To evaluate the results of occipital interhemispheric transtentorial (OITT) approach for tumors in PTV. Thirty-three patients underwent surgery via OITT approach for PTV tumors at Sri Sathya Sai Institute of Higher Medical Sciences during the study period of 5 years (June 2011-May 2016). Ideal trajectory for OITT approach was determined by neuronavigation. Endoscope was used for removing any residual lesion at the blind spots. Postoperative magnetic resonance imaging (MRI) performed in all the patients revealed gross total or near-total (>95%) excision of tumor in 31 patients (93.9%). Preoperative neurological deficits improved either completely or significantly following excision of the tumor in 73.3% (11/15) of the patients. Outcome was good (modified Rankin scale ≤2) at discharge in 93.9% (31/33) and at a final follow-up of 3 months or more in 96.8% (30/31) of the patients. None of the patients died during the postoperative period. Complications included upgaze palsy (transient- 6.1% [2/33], persisting- 3% [1/33]), visual field defects (transient- 3% [1/33], persisting- 3% [1/33]), transient third nerve paresis (1/33-3%), transient hemiparesis (1/33-3%), operative site hematoma (1/33-3%), small posterior cerebral artery (PCA) territory infarct (1/33-3%), and small venous infarct (1/33-3%). At least one follow-up MRI could be performed in 23 patients. Final follow-up MRI revealed no recurrence or increase in the size of the residual lesion compared to postoperative images in 20 patients (20/23-87%) and large recurrence in 3 patients (3/23-13%) with high-grade lesions. Gross total/near-total excision can be performed in majority of the PTV tumors through OITT approach with minimal morbidity and mortality.

Factors affecting global neurocognitive status and frontal executive functions in the early stage after surgical clipping of unruptured anterior circulation aneurysms with respect to keyhole clipping and conventional clipping.

This study investigated the most significant factor for the preservation of the global neurocognitive status and frontal executive functions in the surgical clipping of unruptured anterior circulation aneurysms, specifically in keyhole and conventional clipping procedures. The prospective study that was performed to examine the effects of aneurysm surgery on the patient's global neurocognitive status and frontal executive functions started on April 2016. After exclusion posterior circulation aneurysms, anterior communicating aneurysms treated by interhemispheric approach, giant aneurysms, and paraclinoid aneurysms, 23 patients who were enrolled before May 2017 were treated by conventional clipping, and 18 patients who were enrolled after June 2017 were treated by keyhole clipping. Two patients were excluded from each group due to missing data. Finally, 21 and 16 patients in each group were analyzed, respectively. Three-tesla magnetic resonance imaging was performed before and after surgery to detect the presence of perioperative cerebral infarctions and brain edema. The Mini-Mental State Examination, Frontal Assessment Battery, and Self-Rating Depression Scale scores were obtained before and 1month after surgery. Logistic regression analyses indicated that anterior communicating and internal carotid artery aneurysms were the most significant factors for poor outcomes and that keyhole clipping for these two types of aneurysm was the most significant factor for the preservation of patient global neurocognitive status. Keyhole clipping was also the most significant factor for the preservation of frontal executive functions in patients. Keyhole clipping may be more favorable than conventional clipping for the preservation of the global neurocognitive status and frontal executive functions. Moreover, it may be the most effective factor for preservation of global neurocognitive status when it is indicated for anterior communicating or internal carotid artery aneurysms.

P.143 Adult gangliocytoma arising within the lateral ventricle: A case report and review of the literature

Background: Gangliocytomas are rare neuronal tumors with an incidence of less than 1% of all CNS neoplasms. They are mostly seen in the pediatric age group, localizing within the cerebral cortex, most often the temporal lobe. Methods: We report a case of an intracranial gangliocytoma arising within the lateral ventricle in an adult patient. Our 66-year-old female patient started experiencing progressive generalized weakness, headaches, and confusion prior to presentation. Her neurological examination did not reveal any focal neurological deficits. MRI of the brain showed a diffusely enhancing lobulated mass situated within the frontal horn of the right lateral ventricle with extension into the foramen of Monro and obstructive hydrocephalus. Results: The patient underwent an interhemispheric trans-callosal approach with gross total resection and relief of her hydrocephalous. Pathological examination showed clusters of highly pleomorphic neuron-like cells without evidence of neoplastic glial cells. Histopathological and immunohistochemistry findings were consistent with the diagnosis of gangliocytoma (World Health Organization grade 1). Conclusions: Gangliocytomas are rare low-grade CNS neoplasms that can present in an older population within unusual locations and should be included within the differential whenever a suspicious lesion is encountered.

Feasibility of the frontobasal interhemispheric approach for managing large olfactory groove meningiomas

Feasibility of the frontobasal interhemispheric approach for managing large olfactory groove meningiomas

Surgical Management of Falcotentorial Junction Tumors: A Case Series Report.

ObjectiveThe surgical strategy for falcotentorial junction tumors remains complex. Different approaches are selected according to the location and growth pattern of the tumor and the operator’s experience. This report reviews our single-institution experience in the surgical management of falcotentorial junction tumors.MethodsWe retrospectively reviewed the clinical and imaging data, surgical strategy, and follow-up outcomes of 49 patients treated from 2007 to 2020.ResultAll 49 patients (12 male, 37 female, mean age: 56.3 ± 11.3 years) underwent safe tumor resection. The most common complaints were headache (43%), dizziness (39%), and unstable gait (16%). Thirty percent of the tumors showed calcification, and the computed tomography scans revealed hydrocephalus in 36% of the patients. On magnetic resonance imaging, 43% of the tumors were unilateral. According to the Asari classification, the tumors were divided into inferior (16%), superior (29%), anterior (22%), and posterior (33%) types. The occipital interhemispheric approach (88%) and supracerebellar–infratentorial approach (10%) were primarily used to reach the tumors. The pathology examination results revealed that 85.7% of the tumors were meningioma and 14.3% were hemangiopericytoma. Of the 49 patients, 15 achieved a Simpson grade I resection, and 29 achieved a Simpson grade II resection. The follow-up rate was 77.6% (38/45); 94.7% of patients (36/38) achieved a favorable outcome, and 9 experienced tumor recurrences.ConclusionSurgical approach selection depends on the growth characteristics of the tumor and the degree of venous or sinus involvement. The occipital interhemispheric approach is the most commonly used and safest approach for falcotentorial junction tumors with multiple brain pressure control assistance techniques.

Endoscopic-assisted surgical approach for butterfly glioma surgery.

Gliomas that spread along the white matter tracts of the corpus callosum to both hemispheres have traditionally been considered surgically challenging largely due to the relative complexity of safely achieving complete resections. We present a series of endoscopic-assisted resections of butterfly gliomas with post-operative radiological assessment of EOR and clinical outcome data. Retrospective review of patients who underwent surgical resection of a butterfly glioma from 2007 to 2020. Butterfly gliomas were defined as gliomas, which appeared to arise from the corpus callosum with significant bilateral extension. All records were retrospectively reviewed with operative/clinical outcomes and complications recorded. 70 patients who underwent an endoscopic-assisted transcortical or interhemispheric approach for butterfly glioma resection met inclusion criteria. A unilateral transcortical approach was used in 86% of cases and an interhemispheric approach in 14%. The endoscope enhanced the visualization of the contralateral hemisphere and allowed for resection of tumor, not reached by standard microscopic visualization, in 100% of cases. 90% of resections resulted in greater than a 95% resection rate. Neurological deficits mostly consisted of motor (10%) and memory (6%) deficits and were most common with posterior tumors of the splenium. The endoscopic-assisted transcortical or interhemispheric approach for butterfly glioma resection is effective in achieving a greater than 95% resection with minimal complications. An angled approach allows careful maneuvering around complex anatomic structures and difficult corners, and should be examined further for its clinical benefits in a prospective manner.

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.

Two-stage endoscopic assisted approach for large pineal region and falcotentorial meningioma: first stage paramedian supracerebellar infratentorial approach, second stage interhemispheric occipital transtentorial approach: surgical cases and anatomical study.

Resection of complex falcotentorial meningiomas, growing along the pineal region (PR), and posterior incisural space (PIS) represents a neurosurgical challenge. Here, we present our strategy for effective resection of large falcotentorial meningiomas applying a paramedian supracerebellar infratentorial and interhemispheric occipital transtentorial approach in staged surgeries. We further systematically compared the effectiveness of midline (MSIA) and paramedian (PSIA) supracerebellar infratentorial, as well as interhemispheric occipital transtentorial approaches (IOTA) to operate along the PR and PIS in 8 cadaveric specimens. The staged PSIA and IOTA enabled successful resection of both falcotentorial meningiomas with an uneventful postoperative course. In our anatomo-morphometrical study, superficial vermian veins at an average depth of 11.38 ± 1.5mm and the superior vermian vein (SVV) at 54.13 ± 4.12mm limited the access to the PIS during MSIA. MSIA required sacrifice of these veins and retraction of the vermian culmen of 20.88 ± 2.03mm to obtain comparable operability indexes to PSIA and IOTA. Cerebellar and occipital lobe retraction averaged 14.31 ± 1.014mm and 14.81 ± 1.17mm during PSIA and IOTA respectively, which was significantly lower than during MSIA (p < 0.001). Only few minuscule veins were encountered along the access through PSIA and IOTA. The application of PSIA provided high operability scores around the pineal gland, ipsilateral colliculus and splenium, and acceptable scores on contralateral structures. The main advantage of IOTA was improving surgical maneuvers along the ipsilateral splenium. In summary, IOTA and PSIA may be advantageous in terms of brain retraction, vein sacrifice, and operability along the PR and PIS and can be effective for resection of complex falcotentorial meningiomas.

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.

Keyhole Approach in Cerebral Aneurysm Surgeries.

Pterional approach via standard fronto-temporal craniotomy and interhemispheric approach via bifrontal craniotomy are the gold standards for clipping of cerebral aneurysms in the anterior circulation. Endovascular treatment is now widely used, but subsets of aneurysms are still indicated for surgical clipping. Modern technological advances allow less invasive clipping techniques such as the keyhole approach. This chapter discusses the surgical indications, preoperative simulation, surgical techniques, and pros and cons of keyhole (supraorbital) clipping. Selection of standard craniotomy or keyhole craniotomy should be uncontroversial, but keyhole clipping requires definite surgical indications based on the characteristics of the target aneurysm for safe clipping.