BRAF-mutated suprasellar glioblastoma mimicking craniopharyngioma: illustrative case

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.

OBSERVATIONS

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.

LESSONS

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.

A new classification of parasagittal bridging veins based on their configurations and drainage routes pertinent to interhemispheric approaches: a surgical anatomical study

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.

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.

Transcortical resection of a giant bilobed falcine meningioma

INTRODUCTION

Falcine meningiomas present significant surgical challenges because they often involve the falx bilaterally, are concealed by a significant amount of normal brain parenchyma and are frequently deep in location and in close proximity to the anterior cerebral arteries. Many prefer the interhemispheric approach for these lesions, but this operative corridor is not without risk as venous infarctions and cortical injury can occur.

CLINICAL PRESENTATION

We present an alternative technique utilizing a transcortical approach to resect a giant, bilobed falcine meningioma in a 68-year-old female who presented with progressive abulia, urinary incontinence, and bilateral lower extremity weakness over 2 years. A unilateral right frontal craniotomy and a corticectomy through the right superior frontal gyrus was used to safely resect the entire tumor. The patient tolerated the procedure well and was discharged home without issue. Pathology demonstrated that the lesion was an atypical meningioma and she subsequently received adjuvant fractionated radiotherapy. At 2-year follow-up, she has no neurologic deficits, never developed any postoperative seizures and has not had any evidence of tumor recurrence.

CONCLUSION

The transcortical approach can be used as a safe alternative for resecting falcine meningiomas without adding significant undue risk to the patient.

Endoscopic Total Corpus Callosotomy and Pan Commissurotomy for Lennox-Gastaut Syndrome

BACKGROUND

Corpus callosotomy (CC) is a major disconnection procedure that functionally isolates the cerebral hemispheres, thereby interrupting the spread of epileptic activity from one hemisphere to the other. It is extremely useful in children suffering from non-localized drug refractory epilepsy, especially drop attacks. The technique has evolved from microscopic to minimally invasive endoscopic surgery. The extent of callosotomy also varies based on the institutional practices ranging from anterior 1/3^rd to total corpus callosotomies (TCC). The performance of TCC in conjunction with anterior, posterior, and hippocampal commissurotomies was described for the first time by the senior author from our institution.

OBJECTIVE

To describe the technique of performing endoscopic total corpus callosotomy, and pan commissurotomy using the interhemispheric corridor.

METHODS

A seven-year-old right-handed male child with seizure onset at the age of six months presented with three types of semiologies consisting of myoclonic jerks, frequent head drops and tonic posturing involving right upper and lower limbs with secondary generalization.

RESULTS

Video electroencephalography (VEEG) revealed diffuse slowing of the background, and slow spike and wave pattern. Generalized paroxysmal fast activity (GPFA) was noted in the VEEG, suggestive of LGS. MRI brain revealed bilateral parieto-occipital gliosis and gross brain atrophy. Ictal SPECT localized to left temporo-occipital area, while magnetoencephalography revealed bilateral temporal localization. Patient underwent TCC with pancommissurotomy. The patient was seizure-free (ILAE Class 3) at one-year follow up with no drop attacks, and significant reduction noted in other seizure types.

CONCLUSION

Endoscopic corpus callosotomy and pan commissurotomy using the interhemispheric corridor is an elegant and minimally invasive technique best suited for appropriately selected children with refractory epilepsy.

A Simple Method to Estimate the Trajectory to the Genu of the Corpus Callosum in the Interhemispheric Approach for Distal Anterior Cerebral Artery Aneurysms

In the interhemispheric approach (IHA) for the distal anterior cerebral artery (DACA) aneurysms, the surgical trajectory to a DACA aneurysm is very important because surgeons sometimes encounter the intraoperative disorientation and the premature rupture. The purpose of this study was to clarify the anatomical landmarks indicating the trajectory to the genu of the corpus callosum (GCC) at the early stage of dissection for the correct intraoperative orientation. “Point A” was defined as the crossing point between the frontal bone and the line connecting the projected external acoustic opening (EAO) and the GCC on the midline slice of the sagittal three-dimensional computed tomography angiography (3D-CTA) images. We measured the distance from the nasion to Point A using midline sagittal slice images from 50 patients who underwent 3D-CTA at our institution. The average distance was 7.0 cm (±0.3 cm). Therefore, the direction of the spatula inserted in the direction of the EAO from Point A (7 cm above the nasion) corresponds to the trajectory to the GCC. In DACA aneurysms of the A3 segment, the pericallosal artery distal to the aneurysm can be safely identified by dissecting the interhemispheric fissure distal to the trajectory to the GCC. In DACA aneurysms of the A4 or A5 segment, the parent artery of the aneurysm can be safely identified by dissection along the trajectory to the GCC. Point A and the EAO can be used as landmarks indicating the trajectory to the GCC for the correct intraoperative orientation in the IHA for DACA aneurysms.

Endoscopic Hemispherotomy for Nonatrophic Rasmussen's Encephalopathy

Background

Hemispheric disconnection represents a challenging and major epilepsy surgical procedure. This procedure in experienced hands offers excellent results in terms of seizure outcomes, especially for hemispheric pathologies such as Rasmussen's encephalitis, hemispheric dysplasias, hemimegalencephaly. The technique of hemispherotomy has witnessed various modifications over the years, beginning from anatomical hemispherectomy to the current era of minimally invasive functional hemispheric disconnections.

Objective

This study aimed to describe the technique of performing endoscopic vertical hemispherotomy using interhemispheric corridor developed by the senior author.

Materials and Methods

A 12-year-old girl with seizure onset at the age of 10 years presented with an aura of fear and nausea followed by tonic deviation of eyes to the right and blinking with speech arrest. There were tonic-clonic movements of the right-sided limbs along with ictal spitting and occasional deviation of the angle of mouth to the right. The patient had loss of awareness for the event along with postictal confusion lasting few minutes.

Results

Video electroencephalography (VEEG) revealed left parietocentral and left temporal localization. Serial magnetic resonance imaging (MRI) brain over 3 years revealed progressive left hemispheric changes suggestive of Rasmussen's encephalitis. The patient underwent left-sided endoscopic hemispherotomy. At 2 years follow-up, the patient is seizure-free (ILAE [International League Against Epilepsy] Class 1).

Conclusion

Endoscopic hemispherotomy using the interhemispheric approach is an elegant, minimally invasive, reproducible, safe, and efficacious technique.

Morphological Classification of the Medial Frontal Cortex Based on Cadaver Dissections: A Guide for Interhemispheric Approach

The medial frontal cortex (MFC) is a part of the medial surface of the frontal lobe situated in the rostral portion of the corpus callosum (CC). In a surgical interhemispheric approach (IHA), the MFC covers the anterior communicating artery (Aco) complex until the final stage of dissection. To clarify the anatomical relationship between the MFC and the Aco complex, and to facilitate orientation in IHA, we analyzed the morphological features of the MFC in number, size, and pattern of gyri from the medial surface of the hemisphere in the subcallosal portion using 53 adult cadaveric hemispheres. The mean width of the MFC excluding cingulate gyrus (MFCexcg) was 20.6 ± as mm in the subcallosal portion. MFCexcg consisting of 2, 3, 4, or 5 gyri were observed in 7.5%, 56.6%, 32.1%, or 3.8% of the hemispheres, respectively. Bilateral MFCexcg consisting of >2 gyri were observed in approximately 85% of the hemispheres. Therefore, in many cases, the dissection performed at 2 cm upward from the base of the straight gyrus (SG) or 3–4 gyri of the MFC is sufficient to safely reach the upper portion of the cistern of lamina terminalis located distal to the Aco complex in IHA. The MFC is a good landmark for intraoperative orientation in IHA.

Interhemispheric Approach

The interhemispheric approach is the natural route to reach the parafalcine and paraventricular structures through the interhemispheric fissure. In this chapter, we report the main anterior and posterior corridors of the interhemispheric approach.

Interhemispheric Approach to Anterior Communicating Artery Aneurysm: A Case Illustration

There are two main types of approaches for anterior communicating artery (AcomA) aneurysms, namely pterional approach, and an interhemispheric (IH) approach. Pterional approach is the most common for anterior circulation aneurysms. However, this approach cannot be used without resection of gyrus rectus when aneurysm is located high within the IH fissure and directed posterosuperiorly, which is better handled with IH approach. In this article, we will describe the tricks of IH approach with a case illustration.

A difficult-to-treat Acom aneurysm with the combined vascular anomaly of Acom fenestration and accessory anterior cerebral artery

Background:

Vascular anomaly and aneurysmal formation of an anterior communicating artery (Acom) complex has often been reported. Because of such a complicated relationship between the vascular structure and aneurysms, Acom aneurysm is one of the most difficult aneurysms to treat among other common anterior circulation aneurysms. We experienced an extremely rare and difficult-to-treat case of ruptured Acom aneurysm with the combined vascular anomaly of the Acom fenestration and an accessory anterior cerebral artery (ACA).

Case Description:

A 29-year-old man underwent a clipping surgery for a ruptured Acom aneurysm with an Acom fenestration and an accessory ACA. By reasons of the complicated Acom structure and a posteriorly-projecting aneurysm, the patient was operated via an interhemispheric approach, which is generally reported to provide the best operative view for all types of Acom aneurysms. However, we could not help applying a clip in the narrow working space and the limited operative view, due to the poor mobilization of Acom complex and the interruption by an accessory ACA.

Conclusion:

The interhemispheric approach may exceptionally have a blind area behind the Acom complex in the case of Acom aneurysms with an accessory ACA. Additionally, the aneurysms arising from the Acom fenestration strongly require neurosurgeons to take a more accurate surgical approach to obtain a direct visualization for an aneurysmal neck.

Combined Interhemispheric and Transsylvian Approach for Resection of Craniopharyngioma

We present a 37-year-old male case of cystic suprasellar huge craniopharyngioma, who presented with significant memory disturbance due to obstructive hydrocephalus. Combined interhemispheric and pterional approach was chosen to resect huge suprasellar tumor. Interhemispheric trans-lamina terminalis approach was quite effective to resect third ventricular tumor, while pterional approach was useful to dissect tumor out of basilar perforators and stalk.

The link to the video can be found at: https://youtu.be/BoYIPa96kdo .

Removal of craniopharyngioma via fronto-basal interhemispheric approach

The effectiveness and safety of fronto-basal interhemispheric approach in treating craniopharyngioma were evaluated. In this retrospective study, the safety and effectiveness of fronto-basal interhemispheric approach for surgical resection of craniopharyngioma in 20 patients was analyzed. Of the 20 patients, 12 were men and 8 were women, aged 15–65 years, with an average age of 42.5 years. The course of disease ranged from 1 to 36 months. The craniopharyngioma tumor was completely removed through surgical resection in 18 patients (90%) and partially removed in 2 patients. The pituitary stalk was preserved in 18 patients and 1 patient succumbed during the study period due to large area pulmonary embolism. In conclusion, fronto-basal interhemispheric approach provides better access to the tumor that grows in the sella-hypothalamus and anterior third ventricle region. Using this approach, tumors can be resected while preserving the vital structures such as the pituitary stalk and hypothalamus.

Posterior interhemispheric transfalcine transprecuneus approach for microsurgical resection of periatrial lesions: indications, technique, and outcomes

OBJECT

Surgical exposure of the peritrigonal or periatrial region has been challenging due to the depth of the region and overlying important functional cortices and white matter tracts. The authors demonstrate the operative feasibility of a contralateral posterior interhemispheric transfalcine transprecuneus approach (PITTA) to this region and present a series of patients treated via this operative route.

METHODS

Fourteen consecutive patients underwent the PITTA and were included in this study. Pre- and postoperative clinical and radiological data points were retrospectively collected. Complications and extent of resection were reviewed.

RESULTS

The mean age of patients at the time of surgery was 39 years (range 11-64 years). Six of the 14 patients were female. The mean duration of follow-up was 4.6 months (range 0.5-19.6 months). Pathology included 6 arteriovenous malformations, 4 gliomas, 2 meningiomas, 1 metastatic lesion, and 1 gray matter heterotopia. Based on the results shown on postoperative MRI, 1 lesion (7%) was intentionally subtotally resected, but ≥ 95% resection was achieved in all others (93%) and gross-total resection was accomplished in 7 (54%) of 13. One patient (7%) experienced a temporary approach-related complication. At last follow-up, 1 patient (7%) had died due to complications of his underlying malignancy unrelated to his cranial surgery, 2 (14%) demonstrated a Glasgow Outcome Scale (GOS) score of 4, and 11 (79%) manifested a GOS score of 5.

CONCLUSIONS

Based on this patient series, the contralateral PITTA potentially offers numerous advantages, including a wider, safer operative corridor, minimal need for ipsilateral brain manipulation, and better intraoperative navigation and working angles.

Posterior interhemispheric transfalcine transprecuneus approach for microsurgical resection of periatrial lesions: indications, technique, and outcomes

OBJECT

Surgical exposure of the peritrigonal or periatrial region has been challenging due to the depth of the region and overlying important functional cortices and white matter tracts. The authors demonstrate the operative feasibility of a contralateral posterior interhemispheric transfalcine transprecuneus approach (PITTA) to this region and present a series of patients treated via this operative route.

METHODS

Fourteen consecutive patients underwent the PITTA and were included in this study. Pre- and postoperative clinical and radiological data points were retrospectively collected. Complications and extent of resection were reviewed.

RESULTS

The mean age of patients at the time of surgery was 39 years (range 11-64 years). Six of the 14 patients were female. The mean duration of follow-up was 4.6 months (range 0.5-19.6 months). Pathology included 6 arteriovenous malformations, 4 gliomas, 2 meningiomas, 1 metastatic lesion, and 1 gray matter heterotopia. Based on the results shown on postoperative MRI, 1 lesion (7%) was intentionally subtotally resected, but ≥ 95% resection was achieved in all others (93%) and gross-total resection was accomplished in 7 (54%) of 13. One patient (7%) experienced a temporary approach-related complication. At last follow-up, 1 patient (7%) had died due to complications of his underlying malignancy unrelated to his cranial surgery, 2 (14%) demonstrated a Glasgow Outcome Scale (GOS) score of 4, and 11 (79%) manifested a GOS score of 5.

CONCLUSIONS

Based on this patient series, the contralateral PITTA potentially offers numerous advantages, including a wider, safer operative corridor, minimal need for ipsilateral brain manipulation, and better intraoperative navigation and working angles.

Combined interhemispheric and pterional approach for ACOM and left MCA aneurysms

This video demonstrates combined two separate craniotomies for two difficult unruptured cerebral aneurysms. The anterior communicating artery (ACOM) aneurysm existed at a high position, projected posteriorly, and thus necessitated an interhemispheric approach. Left middle cerebral artery (MCA) aneurysm with complex figure was treated through a separate pterional approach. Meticulous micro-cisternal opening under high magnification enabled safe and effective exposure of both aneurysms with minimal brain retraction, which alleviated brain damage as shown in postoperative images. The video can be found here: http://youtu.be/mBYsaAVekCA .

Twenty-nine cases of resection of suprasellar meningioma through small bone window: an interhemispheric approach

Aim of the study

The present study aims to discuss the value and the effect of resection of suprasellar meningioma through the interhemispheric approach.

Material and methods

Twenty-nine cases of patients with suprasellar meningioma diagnosed through enhanced magnetic resonance imaging (MRI) scans and postoperative histopathological examination underwent resection of tumours (the largest diameter ranged from 3 cm to 6 cm) by the microsurgical technique of a small bone window (about 4 cm × 5 cm) through the interhemispheric approach.

Results

Among all cases, 25 (86%) (Simpson I, II) were of total resection of tumours and 4 were of subtotal resection of tumours. 19 (65%) were of improvement of vision and visual field, 2 (7%) were of postoperative diabetes insipidus, and 1 (3%) was of electrolyte imbalance. No operative death occurred.

Conclusions

The small bone window interhemispheric approach can be used to expose tumours, lightly stretch brain tissues, reduce the incidence of complications, and improve the total resection rate of tumours of patients with sellae meningiomas growing forward, upward, and into the sella.