Falcine Meningiomas: Analysis of the Impact of Radiologic Tumor Extensions and Proposal of a Modified Preoperative Radiologic Classification Scheme

Endoscopic Contralateral Interhemispheric Transfalcine Keyhole Approach for Large Falcine Meningiomas

OBJECTIVE

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.

METHODS

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 3 cm, 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.

RESULTS

An endoscopic contralateral interhemispheric transfalcine keyhole approach was used to resect 4 cases of large falcine meningioma. The mean operation time was 265 minutes (range: 216-294 minutes), 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.

CONCLUSIONS

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.

Anterior Skull Base Meningioma: Surgical Approach and Complication Avoidance

Introduction  Endoscopic endonasal approach (EEA) and keyhole transcranial approaches (TCAs) are being increasingly used in anterior skull base meningioma (ASBM) surgery. Objective  We compare tumor resection rates and complication profiles of EEA and supraorbital keyhole approach (SOKHA) with conventional TCAs. Methods  Fifty-four patients with ASBM (olfactory groove meningioma [OGM], n  = 19 and planum sphenoidale/tuberculum sellae meningioma [PSM/TSM], n  = 35) operated at a single center over 7 years were retrospectively analyzed. Results  The overall rate of gross total resection (GTR) was higher in OGM (15/19, 78.9%) than PSM-TSM group (23/35, 65.7%, p  = 0.37). GTR rate with OGM was 90% and 75% with TCA and EEA. Death ( n  = 1) following medical complication (TCA) and cerebrospinal fluid leak requiring re-exploration ( n  = 2, one each in TCA and EEA) accounted for the major complications in OGM. For the PSM/TSM group, the GTR rates were 73.3% ( n  = 11/15), 53.8% ( n  = 7/13), and 71.4% ( n  = 5/7) with TCA, EEA, and SOKHA, respectively. Seven patients (20%) of PSM-TSM developed major postoperative complications including four deaths (one each in TCA and SOKHA, and two in EEA groups) and three visual deteriorations. Direct and indirect vascular complications were common in lesser invasive approaches to PSM-TSM especially if the tumor has encased intracranial arteries. Conclusion  No single approach is applicable to all ASBMs. TCA is still the best approach to obtain GTR but has tissue trauma-related problems. SOKHA may be a good alternative to TCA in selected PSM-TSMs, while EEA may be an alternate option in some OGMs. A meticulous patient selection is needed to derive reported results of EEA for PSM-TSM.

How Much Tumor Volume Is Responsible for Development of Clinical Symptoms in Patients With Convexity, Parasagittal, and Falx Meningiomas?

Purpose: Meningiomas are the most common primary intracranial neoplasms and clinical symptom appearance depends on their volume and location. This study aimed to identify factors that influence clinical symptoms and to determine a specific threshold tumor volume for the prediction of symptomatic progression in patients with convexity, parasagittal, and falx meningiomas.

Materials and Methods: We retrospectively studied patients with radiologically suspected convexity, parasagittal, or falx meningiomas at our institution.

Results: The data of three hundred thirty-three patients were analyzed. We further divided patients into two groups based on clinical symptoms: an asymptomatic group (250 cases) and a symptomatic group (83 cases). Univariate analysis revealed significant differences between the groups in terms of sex (p = 0.002), age at the time of volumetric analysis (p < 0.001), hyperintense lesions on T2-weighted images (p = 0.029), peritumoral edema (p < 0.001), maximum tumor diameter (p < 0.001), and tumor volume (p < 0.001). Further multivariate analysis revealed significant differences between the groups in terms of age at the time of volumetric analysis (p = 0.002), peritumoral edema (p < 0.001), and tumor volume (p < 0.001). The receiver operating characteristic curve revealed a threshold tumor volume of 21.1 ml for predicting whether a patient would develop symptoms (sensitivity 0.843, specificity 0.880, an area under the curve 0.919 [95% confidence interval: 0.887–0.951]).

Conclusion: We identified factors predictive of clinical symptoms in patients with convexity, parasagittal, and falx meningiomas and determined the first-ever threshold tumor volume for predicting symptomatic progression in such patients.

A rare appearance of the trigeminocardiac reflex during resection of posterior parasagittal meningioma

Background:

Although a well-recognized phenomenon of the tentorium and posterior fossa, the trigeminocardiac reflex (TCR) has been rarely reported during surgery involving the posterior falx cerebri.

Case Description:

We present the case of a 63-year-old woman who underwent repeat resection of an atypical parasagittal meningioma involving the posterior falx. During resection, TCR was repeatedly elicited during manipulation and coagulation of the falx. Air embolism and cardiac etiologies were initially considered while TCR was not suspected, given the location. Ultimately, TCR was recognized when asystole self-resolved upon cessation of stimulus and due to its reproducibility.

Conclusion:

Awareness by the anesthesiologist and neurosurgeon of the possibility of TCR during falcine procedures can help with rapid identification to avoid a potentially catastrophic outcome.

Falcine meningiomas

Falcine meningiomas (FMs) are defined as meningiomas arising from the falx, covered by the overlying brain parenchyma, and not involving the superior sagittal sinus (SSS). FMs together with parasagittal meningiomas represent the second most common location of intracranial meningioma. Clinical presentation depends on the dimensions and location of the FM. Surgery for FM removal deserves several considerations related to bridging veins, anterior cerebral artery branches, arterial feeders, SSS involvement, FM locations, and FM dimensions. In this chapter the principal aspects influencing surgical strategy are analyzed together with approaches and management.

The Dilemma of Multifocality in Insular Tumors: Multicentricity versus Metastasis

Background and Purpose:

Multifocality and metastasis from insular glioma are extremely rare. Pathological insights and elaboration of the clinical course of this condition will contribute to their better understanding.

Materials and Methods:

Among 123 consecutively operated insular gliomas, 5 patients (4.2%) presented with a multifocal tumor. The clinico-radiological, histo-molecular, and treatment outcomes were noted and compared with the unifocal insular glioma cohort.

Results:

Among the five patients, all were males and involved the right insular lobe. Three patients presented with synchronous tumors, while two patients developed metachronous multifocal tumors. The histology of the insular tumor was Grade I glioma in 1, Grade II astrocytoma with p53 mutation in 2, and anaplastic astrocytoma and glioblastoma in one patient each. Histological confirmation of the second lesion was performed in two patients, showing the same histology of the insular tumor. Interconnection between the tumors was apparent through cerebrospinal fluid pathways in four patients, while no such connection could be established in one patient. Barring the patient of Grade I glioma, the rest of the patients died within months of the diagnosis.

Conclusion:

Multifocal insular glioma is rare and probably represents a biologically more aggressive tumor. Insular glioma that touches the ventricle appears a common denominator for multifocality. True multicentricity is rare. The prognosis in insular glioma with multifocality is poor in non-Grade I gliomas.

Is Falcine Meningioma a Diffuse Disease of the Falx? Case Series and Analysis of a "Grade Zero" Resection

BACKGROUND

Falcine meningiomas have unique characteristics including their high rates of recurrence, association with high grade pathology, increased male prevalence, and potential for diffuse involvement of the falx.

OBJECTIVE

To address these issues in a substantial series of falcine meningiomas and report on the impact of extent of resection for this distinct meningioma entity.

METHODS

Retrospective analysis of characteristics and outcomes of 59 falcine meningioma patients who underwent surgery with the senior author. A "Grade Zero" category was used when an additional resection margin of 2 to 3 cm from the tumor insertion was achieved.

RESULTS

For de novo falcine meningiomas, gross total resection (GTR) was associated with significantly decreased recurrence incidence compared with subtotal resection (P ≤ .0001). For recurrent falcine meningiomas, median progression-free survival (PFS) was significantly improved for GTR cases (37 mo vs 12 mo; P = .017, hazard ratio (HR) .243 (.077-.774)). "Grade Zero" resection demonstrated excellent durability for both de novo and recurrent cases, and PFS was significantly improved with "Grade Zero" resection for recurrent cases (P = .003, HR 1.544 (1.156-2.062)). The PFS benefit of "Grade Zero" resection did not achieve statistical significance over Simpson grade 1 during the limited follow-up period (mean 2.8 yr) for these groups.

CONCLUSION

The recurrence of falcine meningiomas is related to the diffuse presence of tumor between the leaflets of the falx. Increased extent of resection including, when possible, a clear margin of falx surrounding the tumor base was associated with the best long-term outcomes in our series, particularly for recurrent tumors.

Coexistent pituitary adenoma and frontal convexity meningioma with frontal sinus invasion: A rare association

The coexistence of pituitary adenoma (PA) and meningioma in the same patient is rare, after excluding radiotherapy-induced meningiomas. Most of the literature on their coexistence describes meningiomas located in the close vicinity to PA, that is, in the sellar/parasellar region. We describe a case of a 65-year-old lady with a nonfunctioning PA and an associated frontal convexity meningioma with frontal sinus invasion. The imaging was nonspecific for the meningioma, and its association with concomitant PA has not been reported before.

A Single-Center Surgical Experience of Interhemispheric Epidermoids and Proposal of a New Radiological Classification

BACKGROUND

Epidermoids account for <1.5% of all intracranial tumors. Overall, the cerebellopontine angle has been the most commonly reported location. In the supratentorial compartment, epidermoids will usually be found in the suprasellar area, sylvian fissure, and intraventricular area. The interhemispheric fissure represents an extremely rare location for supratentorial epidermoids, with limited cases reported previously. Surgery of an interhemispheric epidermoid can be challenging because of its adherence to the anterior cerebral artery branches or the brain parenchyma itself. In the present study, we have reported the largest Series of interhemispheric epidermoid tumors to better understand the clinical behavior, radiological features, and surgical outcomes.

METHODS

In the present study, we retrospectively evaluated the data from 22 consecutive patients with interhemispheric epidermoids treated surgically during the past 10 years (2009-2019) at our center. During the same study period, we had treated 2355 patients with brain tumors (both primary and secondary), including 262 patients with intracranial epidermoids. Therefore, interhemispheric epidermoids comprised 0.009% of all brain tumors and 8.4% of all intracranial epidermoids in our experience. These patients all had newly diagnosed tumors and had undergone surgery for the first time at our center. All surgical specimens had been confirmed histopathologically.

RESULTS

The mean age of the patients was 31 years (range, 17-61 years), with a male predilection. Seizures and headache were the most common mode of presentation. The average tumor size was 5.2 cm (range, 3.5-10 cm). Of the 22 tumors, 21 were in the anterior two thirds of the fissure. Anatomical distortion of the corpus callosum was seen in 13 patients (59%). The extent of excision was total in 17 (77.3%), near total in 3 (13.6%), and subtotal in 2 (9%) patients. The near or subtotal excisions had been necessary because of either tumor adherence to the pericallosal artery (n = 3) or a missed tumor lobule (n = 2). The mean follow-up time was 32 months, with no tumor recurrence.

CONCLUSION

Interhemispheric epidermoids can often reach a large size with substantial lateral extension found at diagnosis. The position of the anterior cerebral Artery branches can help to differentiate interhemispheric epidermoids from radiologically similar corpus callosum, velum interpositum, and cavum septum pellucidum epidermoids. Complete surgical excision with minimal complications is feasible, with good long-term outcomes.

Meningioma in a Postrenal Transplant Case: More than Meets the Eye

BACKGROUND

Patients with a renal transplant are an ever-increasing demographic. Their life expectancy is also on the rise and thus malignancies or tumors in these cases are more frequent. These patients are often on immunosuppressive drugs that are known to cause changes in the microvasculature, especially of the deep white matter. However, benign dural-based lesions are a rarity in these cases with very few (<5) ever being reported. Imaging findings in such cases are altered, which leads to an altered set of differential diagnosis.

CASE DESCRIPTION

We present a case of a right parasagittal lesion in case of postrenal transplant with imaging findings suggestive of an inflammatory lesion. The lesion was excised and histopathology was that of a fibrous meningioma. Pathological basis of altered imaging is discussed and potential causes elaborated along with a thorough review of similar cases and their findings.

CONCLUSIONS

Renal transplants and long-term survival are now a reality; calcineurin inhibitors are a staple for these cases. The drugs alter imaging findings and hence cases need to be carefully evaluated with a host of differential diagnosis. Knowledge of these changes is now necessary for these new spectra of cases.

Modified unilateral approach for mid-third giant bifalcine meningiomas: resection using an oblique surgical trajectory and falx window

BACKGROUND

Utilizing the shortest available trajectory is the norm for excision of meningiomas. However, such an approach for the mid-third/central falcine meningiomas risks the adjoining draining veins and eloquent cortex. A larger size and bilaterality of such tumors adds to the surgical challenge. Herein, we report the surgical nuances of a modified unilateral approach in patients operated for giant bilateral symmetrical mid-third falcine meningiomas.

METHODS

Five such patients were operated. The clinico-radiologic data was studied at presentation and at the follow-up. The meningiomas were subclassified into those that were located in the anterior and posterior half of the central falx, and their surgical trajectory was chosen accordingly. The tumor was excised through an oblique anterior or a posterior trajectory instead of directly working over the major draining veins and eloquent brain. The falx was incised to create a surgical window and access the tumor on the contralateral side.

RESULTS

Four patients had meningiomas in the anterior half and one in the posterior half of central falx. Simpson excision was grade II in four patients. One patient showed small residual tumor and underwent stereotactic radiosurgery. The overall mean follow-up of the patients was 9.2 months. All the patients had good clinical outcome.

CONCLUSIONS

Giant bifalcine meningiomas can be safely resected through a unilateral approach. Falx opening serves as a window to remove the tumor from the contralateral side. An oblique trajectory rather than an end-on access to these tumors minimizes the risk of venous and cortical injury.