Falcotentorial and velum interpositum meningiomas: Two distinct entities of the pineal region

Falcotentorial Meningiomas: Insights from Surgical Strategies and Clinical Outcomes

Background: Falcotentorial meningiomas are exceptionally uncommon tumors, presenting a challenge for neurosurgeons due to their close proximity to vital structures. Gross total resection represents the standard of treatment for these tumors. However, care must be taken when surgically approaching these lesions, since damaging neurovascular structures may cause unacceptable morbidity. Selecting the optimal surgical approach for each tumor is of paramount importance when treating these patients. Methods: The authors reviewed medical records to identify all patients with falcotentorial meningiomas who underwent resection at the University Hospital of Freiburg between January 2001 and December 2021. Clinical and imaging data, surgical management, and clinical outcomes were analyzed. Results: Falcotentorial meningiomas occurred in 0.7% (15 of 2124 patients) of patients with intracranial meningiomas. Of these 15 patients, 8 were female and 7 male. The occipital interhemispheric approach was used in nine patients, the supracerebellar infratentorial approach in five patients, and the retrosigmoidal approach in one patient. Three patients developed visual field deficits after surgical resection. Incomplete resection was significantly associated with tumor progression (p < 0.05). Conclusions: Individualized surgical strategies, guided by preoperative imaging and classification systems, play a crucial role in optimizing patient care. Among the available approaches, the occipital interhemispheric and supracerebellar infratentorial approaches are frequently employed and considered among the safest options for these tumors.

Surgical Treatment of Falcotentorial Meningioma: An Illustrative Case Report and Literature Review

Falcotentorial meningiomas are rare tumors, representing only 2-3% of all intracranial meningiomas. These tumors can grow rapidly, leading to severe neurological complications. They grow at the junction of the tentorium cerebelli and the falx cerebri, in close proximity to the great vein of Galen. The surgical approach depends on several factors, such as the tumor's size, the patency of the straight sinus, and its location, either above or below the tentorium. Complete removal of the tumor in this area is difficult due to its deep location near major neurovascular structures. Various surgical approaches can be employed to remove these tumors, and the decision on which approach to use should be based on its advantages and disadvantages.

Combined supracerebellar infratentorial and right occipital interhemispheric approach to falcotentorial junction meningioma: A case report

Background

Falcotentorial meningioma is a rare tumor of pineal region, arising from the dural folds where the tentorium and falx meet. Due to the deep location and near closeness to significant neurovascular structures, gross-total tumor resection in this area can be complicated. Pineal meningiomas can be resected using a variety of approaches; however, all these approaches are associated with a significant risk of postoperative complications.

Case Description

A 50-year-old female patient who presented with several headaches and visual field defect and diagnosed with pineal region tumor is discussed in the case report. Patient was successfully managed surgically by combined supracerebellar infratentorial and right occipital interhemispheric approach. Cerebrospinal fluid circulation was restored after surgery and neurological defects were regressed.

Conclusion

Our case shows that it is possible to completely remove giant falcotentorial meningiomas with minimal brain retraction, preserve the straight sinus and vein of Galen, and prevent neurological impairments by combining two approaches.

Falcotentorial Meningiomas: Optimal Surgical Planning and Intraoperative Challenges - Case Report and a Review

Meningiomas arising from the falcotentorial junction are rare, and the selection of the optimal surgical approach is essential. We report a falcotentorial meningioma (FTM) case approached by occipitotranstentorial resection and subtotal tumor resection presenting a satisfactory clinical outcome. The present review sought to reveal the current knowledge regarding the clinical presentation, radiological imaging, and the microsurgical anatomy of FTMs as a form of improving the surgical approach. The selection of the optimal surgical approach is essential for the safe and effective removal of an FTM. Preoperative imaging analysis should identify the anatomical relations of the tumor and guide toward the least disruptive route that preserves the neurovascular structures.

Surgical Management of Falcotentorial Junction Tumors: A Case Series Report

Objective

The 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.

Methods

We retrospectively reviewed the clinical and imaging data, surgical strategy, and follow-up outcomes of 49 patients treated from 2007 to 2020.

Result

All 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.

Conclusion

Surgical 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.

Occipital Interhemispheric Transtentorial Approach for a Pineal Region Meningioma with Pseudobulbar Palsy

Meningiomas represent 8%-10% of all pineal region (PR) tumors. When they arise from the falx, tentorium, or tentorial incisura, they are not always considered a true PR tumor, as they do not originate from it but instead only grow toward the region. The true meningioma of PR must be originated from the arachnoid envelope of the pineal gland or from the 2 leaflets of the velum interpositum. In both conditions there are no dural attachments.^1,2 Occipital interhemispheric transtentorial and supracerebellar infratentorial are the 2 main approaches for tumors within this region. Aside from the surgeon's preference, the position of the venous system and the direction of the tumor growth guide the approach choice. Endoscope assistance can help reach areas unable to be visualized under the microscope.^3-5 We report the case of a 37-year-old female with a large PR meningioma (velum interpositum) presenting with intense dysphagia, dysphonia, and bilateral tongue palsy. Given the affected bilateral upper motor tracts associated with bulbar symptoms, a diagnosis of pseudobulbar palsy was considered.^6,7 Preoperative imaging also showed compression of the deep venous system. The patient underwent a total resection of the tumor via an occipital interhemispheric transtentorial approach and exhibited a dramatic recovery of neurologic symptoms after the surgery (Video 1). Postoperative venogram showed restoration of the usual deep venous system pattern, which may be associated with significant neurologic improvement. Careful management of the deep veins is mandatory during the resection of PR meningiomas. The venous system improvement after the surgery may be associated with the dramatic recovery seen in this unique case. The patient consented to publication of her images.

Combined Microscopic and Endoscopic Surgery for Pineal Region Meningiomas Using the Occipital-Parietal Transtentorial Approach

Objective

Pineal region meningiomas are deeply located and adjacent to critical neurovascular structures, making them one of the most challenging areas to access. The authors presented a combined microscopic and endoscopic surgery and investigated its value in resecting pineal region meningiomas.

Methods

Twelve patients with pineal region meningiomas from February 2017 to December 2020 were retrospectively reviewed. All patients underwent combined microscopic and endoscopic surgery using the occipital-parietal transtentorial approach. Perioperative clinical, surgical, and radiographic data were collected.

Results

The endoscope provided a wider view and increased visualization of residual tumors. All tumors were completely resected, and none of the patients died. Total resection was believed to have been achieved in four patients, but the residual tumor was detected after endoscopic exploration and was completely resected with an endoscope. Only one patient had transient visual field deficits. No recurrence was observed during follow-up.

Conclusions

Combined microscopic-endoscopic surgery for pineal region meningiomas eliminates microscopic blind spots, thus compensating for the shortcomings of the traditional occipital transtentorial approach. It is a promising technique for minimally invasive maximal resection of pineal region meningiomas.

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 ± 1.5 mm and the superior vermian vein (SVV) at 54.13 ± 4.12 mm limited the access to the PIS during MSIA. MSIA required sacrifice of these veins and retraction of the vermian culmen of 20.88 ± 2.03 mm to obtain comparable operability indexes to PSIA and IOTA. Cerebellar and occipital lobe retraction averaged 14.31 ± 1.014 mm and 14.81 ± 1.17 mm 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.

Pineal Region Meningioma in a Very Young Child

INTRODUCTION

Meningiomas in childhood are infrequently seen. Furthermore, they are extremely rare at a pineal location with few reported cases above 5-years of age. We present a very young child with a large pineal region meningioma which mimicked the usually occurring pathologies at this site.

CASE PRESENTATION

A 2.5-year-old child presented with symptoms of raised intracranial pressure. MRI demonstrated a homogenously enhancing pineal lesion with small cystic areas. After an initial cerebrospinal fluid evaluation for germ cell tumors, the child underwent excision of the lesion by the Krause approach. The tumor showed no definitive dural attachment, had well-defined arachnoid interface, and was completely excised. The final histopathology was meningioma.

CONCLUSION

Although unusual, we highlight the importance of considering meningiomas among the childhood pineal region lesions, given their good outcome with total resection. Also, pertinent brief literature of the pediatric pineal region meningiomas has been provided. An assessment of preoperative and intraoperative features (clear arachnoid plane) along with adjuncts such as frozen studies can help discern various entities of this region, and decide the extent of excision.

Surgical treatment of falcotentorial meningiomas: a retrospective review of a single-institution experience

OBJECTIVE

Meningiomas at the falcotentorial junction represent a rare subgroup of complex meningiomas. Debate remains regarding the appropriate treatment strategy for and optimal surgical approach to these tumors, and surgical outcomes have not been well described in the literature. The authors reviewed their single-institution experience in the management, approach selection, and outcomes for patients with falcotentorial meningiomas.

METHODS

From the medical records, the authors identified all patients with falcotentorial meningiomas treated with resection at the Barrow Neurological Institute between January 2007 and October 2017. Perioperative clinical, surgical, and radiographic data were retrospectively collected. For patients who underwent the supracerebellar infratentorial approach, the tentorial angle was defined as the angle between the line joining the nasion with the tuberculum sellae and the tentorium in the midsagittal plane.

RESULTS

Falcotentorial meningiomas occurred in 0.97% (14/1441) of the patients with meningiomas. Most of the patients (13/14) were female, and the mean patient age was 59.8 ± 11.3 years. Of 17 total surgeries (20 procedures), 11 were single-stage primary surgeries, 3 were two-stage primary surgeries (6 procedures), 2 were reoperations for recurrence, and 1 was a reoperation after surgery had been aborted because of brain edema. Hydrocephalus was present in 5 of 17 cases, 4 of which required additional treatment. Various approaches were used, including the supracerebellar infratentorial (4/17), occipital transtentorial/transfalcine (4/17), anterior interhemispheric transsplenial (3/17), parietal transventricular (1/17), torcular (2/17), and staged supracerebellar infratentorial and occipital transtentorial/transfalcine (3/17) approaches. Of the 17 surgeries, 9 resulted in Simpson grade IV resection, and 3, 1, and 4 surgeries resulted in Simpson grades III, II, and I resection, respectively. The tentorial angle in cases with Simpson grade I resection was significantly smaller than in those with an unfavorable resection grade (43.3° ± 4.67° vs 54.0° ± 3.67°, p = 0.04). Complications occurred in 10 of 22 approaches (17 surgeries) and included visual field defects (6 cases, 2 permanent and 4 transient), hemiparesis (2 cases), hemidysesthesia (1 case), and cerebellar hematoma (1 case).

CONCLUSIONS

Falcotentorial meningiomas are challenging lesions. A steep tentorial angle is an unfavorable preoperative radiographic factor for achieving maximal resection with the supracerebellar infratentorial approach. Collectively, the study findings show that versatility is required to treat patients with falcotentorial meningiomas and that treatment goals and surgical approach must be individualized to obtain optimal surgical results.

Reinvestigation of the origins of pineal meningiomas based on its related veins and arachnoid membranes

BACKGROUND

A series of patients harboring pineal region meningiomas were respectively analyzed to explore the origin of these tumors and the true meaning of the term "velum interpositum (VI) meningiomas".

METHODS

21 patients with pineal meningiomas underwent operation in Nanfang Hospital of Southern Medical University from January 2005 to December 2016 were retrospectively included to analyze the clinical features, imaging findings and surgical video data of these patients. According to the method of literature, the data of this group were also divided into falcotentorial (FT) meningiomas and VI meningiomas, and the differences between the two types of tumors were compared.

RESULTS

Among the 21 cases of tumor, there were 12 cases of FT meningiomas, including 4 cases originating from cerebral falx, 4 cases from tentorium of cerebellum and 4 cases from straight sinus; there were 9 cases of VI meningiomas, 7 of which originated from the arachnoid sleeve of the Galen vein, 1 from the posterior part of the internal cerebral vein and 1 from the posterior surface of the pineal gland. Postoperative pathological examination showed meningiomas in all the 21 patients, including 16 cases of total resection and 5 cases of subtotal resection. Postoperatively limitation of binocular vertical motion was found in 3 cases, homotropic hemianopia in 7 cases, hemiplegia in 1 case and death in 1 case.

CONCLUSIONS

This study suggests that pineal meningiomas are more suitable to be described by FT meningioma and meningiomas of the arachnoid of the pineal region by analyzing the origin of tumors. The term "VI meningiomas" can only reflect a part of meningiomas of the arachnoid of the pineal region. Before the removal of pineal meningiomas, more attention should be paid to the effects of the two types of tumors on the Galen vein and the straight sinus, and the establishment of venous collateral circulation.

Trochlear Schwannoma Arising from Transition Zone of Nerve Sheath in the Pineal Region: Case Report and Review of the Literature

BACKGROUND

This report presents the third case of trochlear schwannoma arising from the pineal region and the first case to be resected using a paramedian infratentorial supracerebellar approach. Schwannomas of cranial nerves have traditionally been thought to arise from the transitional point where the axonal envelopment switches from glial cells to Schwann cells; however, recent temporal bone histopathologic evidence from vestibular schwannomas challenges this view. Of the 38 cases of pathology-confirmed trochlear schwannoma in the literature, there are only 2 cases arising from the pineal region, where the nerve sheath transition zone is located. Here, we discuss an unusual case of trochlear schwannoma arising from this transition zone.

CASE DESCRIPTION

A 65-year-old man was admitted to our institute after a traffic accident. He complained of headache and dizziness, and a computed tomography scan revealed an isodense mass in the pineal region with obstructive hydrocephalus. Magnetic resonance imaging with contrast showed an enhancing mass in the pineal region. The tumor was subtotally resected using a paramedian infratentorial supracerebellar approach, and pathology confirmed the diagnosis of trochlear schwannoma.

CONCLUSIONS

Trochlear schwannoma should be considered when a mass is identified in the pineal region. This diagnosis should still be entertained for mass lesions along the free tentorial edge because the tumor may arise distant from the glial-Schwann transition zone located by the dorsal midbrain. We propose a treatment algorithm for this rare tumor that seeks to maximize functional outcome.

Falcotentorial meningiomas

Falcotentorial meningiomas are uncommon tumors that account for 1%-2% of all intracranial meningiomas. They arise at the junction of the falx cerebri and tentorium, from the entry of the vein of Galen posteriorly to the confluence of venous sinuses. Treatment for these tumors depends on patient and tumor factors. Tumor factors include size of the tumor, patency of the straight sinus, and the amount of tumor above and/or below the tentorium. This chapter reviews the clinical presentation, imaging features, treatment options, and results.

Extent of Resection and Long-Term Survival of Pineal Region Tumors in Helsinki Neurosurgery

BACKGROUND

Pineal region tumors represent challenging surgical lesions with wide ranges of survival reported in different surgical series. In this article, we emphasize the role of complete microsurgical resection (CMR) to obtain a favorable long-term outcome of pineal region tumors.

METHODS

We report a retrospective study of pineal region tumors operated on in Helsinki Neurosurgery between 1997 and 2015. Information was obtained from the hospital records, and an evaluation of the Finnish population register was conducted in July 2018 to determine the current status of the patients.

RESULTS

A total of 76 pineal region tumors were operated on. The survival was 62% at a mean follow-up of 125 ± 105 months (range, 0-588 months), and the disease-related mortality was limited to 14 patients (18.4%). Up to July 2018, 29 patients had died. Two patients died 1 and 3 months after surgery of delayed thalamic infarctions, 12 patients of disease progression, and 15 had non-disease-related deaths. Only 1 patient was lost in the long-term follow-up. Ten of 14 disease-related deaths occurred during the first 5 years of follow-up: 5 diffuse gliomas, 3 germ cell tumors, 1 grade II-III pineal parenchymal tumor of intermediate differentiation, and 1 meningioma. CMR was linked to better tumor-free survival and long-term survival, with the exception of diffuse gliomas.

CONCLUSIONS

CMR, in the setting of a multidisciplinary management of pineal region tumors, correlates with favorable survival and with minimal mortality. Surgically treated grade II-IV gliomas constitute a particular group with high mortality within the first 5 years independently of the microsurgical resection.

Retractorless interhemispheric transtentorial approach for large lesions in the posterior incisural space

Background:

Surgical resection of lesions in the posterior incisural space presents a significant surgical challenge, which may result in postoperative visual complications and other neurological deficits. We, therefore, describe a retractorless interhemispheric transtentorial approach that avoids surrounding brain structures with positive outcomes and no complications or visual damage.

Case Description:

We present four cases of lesions in the posterior incisural space that was treated with a retractorless interhemispheric transtentorial approach. Two patients were previously seen at another institution for a falcotentorial meningioma. We resected the meningiomas with a parietal-occipital interhemispheric transtentorial approach with no neurological deficits. A third patient presented with a large superior vermian hemangioblastoma with a steep angle of the tentorium. The fourth patient had a large upper vermian metastatic lesion with progressive enlargement, which was refractory to radiation treatments and chemotherapy, and we achieved partial resection. Postoperative visual function was completely preserved in all patients.

Conclusion:

A carefully executed retractorless interhemispheric approach in select cases is an effective option to reduce morbidity and prevent visual complications when removing lesions in the posterior tentorial incisure.

Meningiomas Originated at the Falcotentorial Region: Analysis of Topographic and Diagnostic Features Guiding an Optimal Surgical Planning

BACKGROUND

Meningiomas arising at the pineal region are a rare entity and still represent a great neurosurgical challenge given their deep location and critical neuroanatomic relationships. The optimal surgical approach to treat these lesions is still under debate. Our objective is to review the topographic and diagnostic features of these lesions, which can help to guide an optimal surgical outcome.

METHODS

We present 2 clinical cases of falcotentorial meningiomas successfully treated at our institution (2016-2017) with different surgical approaches. A literature review is performed, and a description of the classification, anatomic relationships, clinical features, diagnosis, and different surgical options and outcomes of these lesions is presented.

RESULTS

The first patient was treated via a supracerebellar infratentorial approach, and the second patient was treated via a parieto-occipital interhemispheric approach. In both tumors, a gross total resection was achieved with no permanent neurologic deficits. In the literature review, gross total resection rates range from 33% to 100%, with no differences regarding the type of meningioma or the surgical approach performed. Permanent neurologic morbidity varies from 0% to 50%, and mortality rates range from 0% to 23%. The distortion and displacement of the vein of Galen and straight sinus represent the most important feature in the decision of optimal surgical approach.

CONCLUSIONS

Pineal region meningiomas represent very infrequent, challenging lesions, and their description in the literature is scarce. The systematic topographic classification of these tumors and evaluation of the neuroanatomic structures involved are crucial to guide a safe and optimal surgical approach and achieve satisfactory outcomes.

Surgical Management of Anterolateral and Posteromedial Incisural Tentorial Meningioma

BACKGROUND

Tentorial meningiomas are a broad and consistent category of tumors but their definition is still unclear and their classification uncertain.

OBJECTIVE

To report the clinical and surgical characteristics of tentorial hiatus meningiomas based on a revised classification of tentorial meningiomas.

METHODS

We reviewed the records of 14 patients who had undergone microsurgical removal of incisural tentorial meningioma. Two tumor subgroups, anterolateral (AL) and posteromedial (PM), were distinguished according to their site of attachment: the middle third and the posterior third of the tentorial free margin, respectively. Clinical presentation, radiological findings, surgical approaches, extent of resection, and outcome were compared.

RESULTS

The 2 subgroups differed by tumor size (larger in PM), incidence of the direction of growth (infratentorial in PM), and hydrocephalus (only in PM), as well as by some clinical aspects. Surgical approach depended on tumor location: lateral (pterional, subtemporal, and retromastoid) for AL lesions; medial (occipital or supracerebellar infratentorial) for PM lesions. Total removal (Simpson grade I-II) was performed in 64% of cases and complications occurred in 14%. Stereotactic radiosurgery was performed in cases of incomplete resection. At a mean follow-up of 104.5 mo, clinical improvement with low recurrence (9%) was achieved.

CONCLUSION

Reallocation of tentorial edge meningiomas is the premise to compare treatment and further improve the approach case-by-case. In spite of their deep site, good outcomes can be achieved in both AL and PM tentorial meningiomas. Also of note is the indolent behavior of residual tumor.

Significance of the Tentorial Alignment in Protecting the Occipital Lobe with the Poppen Approach for Tentorial or Pineal Area Meningiomas

OBJECTIVE

We aimed to identify the factors that can predict the risk of occipital lobe damage preoperatively when resecting tumors located at the tentorial or pineal regions with the occipital-transtentorial approach (Poppen approach).

METHODS

In 27 consecutive patients who underwent tumor resection with the Poppen approach for tentorial or pineal region meningiomas, the following morphologic parameters were assessed on a preoperative magnetic resonance imaging: (1) tentorial angle, (2) tentorial length, and (3) the shortest distance from the confluence of the sinus to the tumor. These parameters, together with tumor size, texture, and resection extent, were correlated with occipital lobe damage by using the one-way analysis of variance, χ², or Fisher's exact tests.

RESULTS

The mean value was 55.3° ± 5.6° (range, 45°-66°) for the tentorial angle, which was significantly associated with the occipital lobe damage grades (P = 0.008), but this was not the case for the tentorial length (P = 0.802) and the shortest distance from the confluence of the sinus to the tumor (P = 0.695). Interestingly, age was also strongly associated with occipital lobe damage risk (P = 0.020). The patients in the subgroup with no occipital damage (grade 4) were the youngest (aged 47.3 years), compared with other grades, with age of 58.0 years for grade 1, 54.3 years for grade 2, and 58.6 years for grade 3. These 2 parameters were also significant after multivariate analysis. No correlation was observed between either tumor nature or the extent of resection and damage grades.

CONCLUSIONS

The risk of occipital lobe damage increases in the presence of a steep tentorial angle during the Poppen approach for tentorial or pineal area tumors. Awareness of such anatomic features preoperatively is important for minimizing operative complications.

Surgical Treatment for Falcotentorial Meningiomas

Among intracranial meningiomas, falcotentorial meningiomas, occurring at the junction of the falx cerebri and tentorial dural folds, are extremely rare. Because of their deep location, they are surrounded by critical structures, and have been regarded as one of the most challenging lesions for surgical treatment. In this study, we describe our surgical strategy for falcotentorial meningiomas and provide a review of our experience.

Two cases of pineal-region meningiomas derived from arachnoid membrane over the vein of Galen without dural attachment

BACKGROUND

We present two rare cases of pineal-region meningiomas. These tumors are the first reported cases of dura-unrelated meningiomas originating from the arachnoid membrane over the vein of Galen (AMG).

CASE DESCRIPTION

In Case 1, a 37-year-old woman presented with a progressing headache. Magnetic resonance imaging (MRI) showed a large tumor in the pineal region, displacing the vein of Galen upward. Angiography disclosed occlusion of the vein of Galen, with deep venous flow draining through the veins on the right medial surface of the occipital lobe to the superior sagittal sinus. In Case 2, a 67-year-old man presented with dizziness. MRI demonstrated a large mass in the pineal region, displacing the vein of Galen inferiorly. Angiography disclosed occlusion of the vein of Galen, with deep venous flow draining through the collateral venous channel into the transverse sinus. Both tumors were totally excised (Simpson Grade III for Case 1, Grade I for Case 2) via a left occipital transtentorial approach. No dural attachment was recognized in either case, but the tumor in Case 1 was firmly adherent to the inferior portion of the AMG, while that in Case 2 was attached to the superior portion of the AMG, but remained dissectible.

CONCLUSIONS

We reported two cases of pineal-region meningiomas originating from the arachnoid membrane over the vein of Galen, resulting in meningioma without dural attachment. These tumors can be totally resected by careful dissection of the tumor from the arachnoid membrane surrounding the vein of Galen.