Abstract

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.

Keywords: Case report, Combined approach, Falcotentorial meningioma, Occipital interhemispheric approach, Pineal region, Supracerebellar infratentorial approach

INTRODUCTION

The pineal region is an unusual location for meningiomas, accounting for 3–8% of tumors in this region.[ 3 ] Pineal region meningiomas are classified into two subtypes based on tumor origin: falcotentorial and velum interpositum meningiomas.[ 6 ] Falcotentorial meningiomas are uncommon tumors of the pineal area that grow from the dural folds where the tentorium and falx meet. Falcotentorial junction meningiomas are relatively rare, accounting for only 0, 3–2% of all meningiomas.[ 5 , 8 , 19 ] Falcotentorial meningiomas, like other meningiomas, are more common in women, with a median age of 59.8 ± 11.3 years.[ 4 , 8 , 11 , 16 , 18 ] However, Gendle et al. presented a case of a 2.5-year-old child with pineal region meningioma.[ 7 ] The pineal gland, midbrain, vein of Galen, straight sinus, and third ventricle are among the adjacent structures that are compressed by falcotentorial meningiomas.[ 5 , 6 ] Most of these tumors have a slow rate of growth,[ 5 ] and they often manifest symptoms of brainstem compression and intracranial hypertension.[ 10 ] This region’s tumors present with hydrocephalus, cerebellar, ophthalmologic, endocrinologic, and cognitive disturbances.[ 8 , 10 , 12 , 18 , 19 ] The predominant presenting symptom of obstructive hydrocephalus caused by the Sylvian aqueduct tumor was headache, which was followed by vomiting and papilledema.[ 12 ] Elevated intracranial pressure and supratentorial lesions are frequently accompanied by ophthalmologic signs such as a narrowing of the visual field, blurry vision, or scotomas.[ 18 ] However, it is possible that it is an magnetic resonance imaging (MRI) incidental finding with intact neurological function.[ 9 , 13 ] Due to the deep location and near closeness to significant neurovascular structures, gross-total tumor resection in this area can be complicated.[ 15 ] Pineal meningiomas can be resected using a variety of approaches. The most widely used approaches are anterior interhemispheric transsplenial, supracerebellar infratentorial, occipital interhemispheric, and occipital transtentorial.[ 15 , 19 ] Each of these approaches has blind spot-related limitations and complications, though.[ 6 , 15 ] In this case, we present the falcotentorial meningioma, which successfully underwent a combined supra and infratentorial approach.

CASE PRESENTATION

A 50-year-old right-handed woman presented with a 4-month history of headaches, a progressive decrease in vision, a gait disorder, and sleep disturbances. Neurological examination revealed cerebellar ataxia; eye examination showed papilledema and right inferior quadrantanopia. Contrast brain MRI showed a large smooth, oval, well circumscribed mass (43 × 36 × 35 mm) in the pineal region, mass effect, and ventricular enlargement [ Figures 1a - f ]. It severely displaced the midbrain and thalamus, compressing the aqueduct and invading the straight sinus and vein of Galen.

Figure 1:

Brain magnetic resonance imaging (MRI). Preoperative axial (a), sagittal (b), and frontal (c) contrast T1-weighted image and axial (d), sagittal (e), and frontal (f) T2-weighted images demonstrates a large (43 × 36 × 35 mm) and homogenously enhancing tumor in the pineal region, occluding the aqueduct, and results in the hydrocephalus.

Resection of the lesion was performed through an occipital craniotomy in combination with a suboccipital craniotomy. The patient was in the three-quarter prone position with the neck flexed and the torso elevated about 30° [ Figure 2a ]. Intraoperative mannitol and steroids were used to reduce edema and intracerebral pressure and minimize the need for retraction. A midline skin incision was made in the occipital region, and an occipital bone flap was fashioned [ Figures 2b and c ]. First, the supracerebellar infratentorial approach was performed [ Figure 3a ], and a gray-yellow mass that grows in the capsule was identified in the pineal region [ Figures 3b and c ]. The capsule of the tumor was separated from surrounding brain tissue and attached vessels, and the infratentorial component of the tumor was removed through dissection and bipolar coagulation under intraoperative neurophysiological monitoring. During the tumor removal, the vein of Galen and the pineal gland were identified and preserved [ Figure 3d ]. The supratentorial component of the tumor is resected through a right occipital interhemispheric approach. The U-shaped dural opening over the transverse sinus is done on the right side of the sagittal sinus [ Figure 3e ]. The right occipital lobe was carefully retracted, and the superior part of the tumor was dissected from the medial part of the occipital lobes and the spleen of the corpus callosum and removed [ Figure 3f ]. After the tumor was removed, cerebrospinal fluid circulation was restored. Simpson Grade I resection was achieved. The surgery was performed under the control of a surgical microscope (OPMI PENTERO 900 Zeiss). The histopathologic diagnosis was transitional meningioma (WHO Grade 1, ICD-O code 9537/0) [ Figure 4 ]. The patient was discharged on postoperative day 14 with a regression of headache and visual field defects. A control brain MRI with contrast-enhancement [ Figure 5 ], performed 3 months after the surgery, shows total tumor removal and hydrocephalus regression due to the restoration of cerebrospinal fluid flow.

Figure 2:

(a) Patient positioning in the operating room. (b) CT 3D reconstruction of the patient’s head with a black arrow indicating the midline occipital incision (dashed line). (c) Postoperative CT 3D reconstruction demonstrating craniotomy extension (dashed black arrow).

Figure 3:

Intraoperative view. (a) Surgical corridor via supracerebellar infratentorial approach. (b and c) The pineal region tumor visualization. (d) Identifying the Vein of Galen. (e) Surgical corridor via right occipital interhemispheric approach. (f) visualization of the superior part of the tumor. (OPMI PENTERO 900 ×6).

Figure 4:

A histological specimen from the tumor resection demonstrates transitional meningioma, WHO Grade 1, ICD-O code 9537/0. Hematoxylin and eosin (×200). A pathological examination was carried out using an Axioskop 40 microscope by Carl Zeiss (Germany) and a panoramic MIDI scanning microscope, with a total magnification of ×200. The hematoxylin and eosin stained slides demonstrated meningothelial cells with bundles of elongated cells that form collagen and reticulin fibers. The nuclei are oval, round, spindle-shaped, and monomorphic.

Figure 5:

Postoperative axial contrast T1-weighted (a), sagittal T2-weighted (b), and CE-FLAIR coronal (c) MRI scans showing tumor removal through a combined supracerebellar infratentorial and occipital interhemispheric approach and the surgical corridor.

DISCUSSION

The pineal region is located in the posterior part of the incisural space, consists of the pineal body within the quadrigeminal arachnoidal cistern, and is bordered by vital structures including the third ventricle, mesencephalic tectum, thalamus, corpus callosum, and vein of Galen.[ 17 ] The velum interpositum meningioma and the falcotentorial meningioma are the two forms of meningiomas that can develop in the pineal region. Falcotentorial meningioma arises in close proximity to the edges of the falcotentorial junction and the confluence of the Galen vein. This tumor features straight sinus infiltration as well as dural attachment and pineal area invasion.[ 14 , 15 , 18 ] Falcotentorial meningiomas might be challenging to perform surgery on due to the blood supply from the tentorial branch of the meningohypophyseal trunk, in addition to critical anatomical structures, local venous anatomy, and posterior choroidal arteries.[ 8 , 19 ] They can, however, be successfully handled with the right strategic planning. The tumor’s location, size, and direction of growth all had a significant impact on the surgical approach.[ 8 ]

Treatment options for falcotentorial meningioma include supracerebellar infratentorial, occipital interhemispheric, occipital transtentorial, anterior interhemispheric transsplenial, or a combination of supra and infratentorial transsinus, midline occipital, and suboccipital approaches.[ 3 , 5 , 6 , 8 - 10 , 13 , 15 , 19 ] The rate of complications related to the approach itself continues to be significant because the ventral side of the falcotentorial margins and the cranial side of the vein of Galen confluence are blind areas.

Asari et al. classified the four types of falcotentorial meningiomas as anterior, inferior, posterior, and superior based on the direction of tumor extension.[ 1 ] According to the location of the dural origin, the displacement of the vein of Galen, and the extension of the tumor, Bassiouni et al. categorized them into four types.[ 2 ] For meningiomas with an anterior type (Asari), Okada et al. preferred the parietoccipital interhemispheric transfalcine and transbitentorial approach. However, this approach is related to precuneus retraction and visual impairments.[ 15 ] The occipital transtentorial/transfalcine corridor is recommended by Nowak et al. for its minimal risk of air embolism, good internal cerebral vein, and midbrain anatomy visibility.[ 14 ]

The supratentorial and infratentorial regions are both exposed by the occipital transtentorial/transfalcine approach and its modifications.[ 6 , 19 ]

For a superiorly located falcotentorial meningioma, endoscopic-assisted microsurgical excision could be performed using the posterior interhemispheric retrocallosal transfalcine approach. The combination bioccipital suboccipital transsinus transtentorial technique, which involves dividing the less dominant transverse sinus, was described by Liu and Cohen.[ 10 ] The distance to the tumor is relatively long in the anterior interhemispheric approach, which is further complicated by VFD, hemiparesis, or hemidysesthesia induced by over-retraction of the interhemispheric fissure.[ 9 , 19 ] If the lesion extended laterally and superiorly, the parietal transventricular approach might be performed. The supracerebellar approach, which Krause first successfully used in 1913, is advantageous for Type II Bassioni and posterior/infratentorial Asari meningiomas. An extremely steep tentorial angle, on the other hand, is not favorable for a supracerebellar infratentorial approach.[ 19 ]

In general, all these approaches are associated with a significant risk of postoperative complications (29%). A safe approach for giant and complicated falcotentorial meningiomas seems to be a combination of approaches. For patients with falcotentorial meningiomas, the choice of approach should be personalized to control tumor growth while preventing approach-related complications.[ 19 ]

Here, we present a case of successfully removing giant falcotentorial meningiomas using a combined supracerebellar infratentorial and interhemispheric occipital approach. Due to the blind spot, we think that a single supracerebellar infratentorial approach is inadequate for anterior type Assari meningiomas with galenic veins displaced contralaterally (Bassiouni Type III). While complete removal without tentorium resection is not achievable with an occipital interhemispheric approach. For this reason, in our case of a large falcotentorial meningioma, we decided to combine these two methods to minimize occipital lobe retraction and achieve maximally safe tumor resection. We preferred the three-quarter prone position because it is associated with low the risk of air embolism and pneumocephalus during the prolonged operation. In our case, a significant proportion of the tumor was found to be infratentorial, and the supracerebellar infratentorial approach was used first to aim to debulk the tumor and improve the visualization of the vein of Galen. Following that, a right occipital interhemispheric approach was used to remove the supratentorial residual tumor. While the supratentorial portion of the tumor can be completely resected by an occipital interhemispheric approach, the great cerebral vein is visible clearly from the supracerebellar infratentorial corridor.

CONCLUSION

Our case demonstrates that by combining two techniques, it is possible to totally remove large falcotentorial meningiomas without external ventricular drainage placement, and with minimal brain retraction, preserve the straight sinus and vein of Galen, and avoid neurological deficits.

Authors’ contributions

All authors contributed to the design and implementation of the article, to the analysis of the results and to the writing of the manuscript.

Ethics approval and consent to participate

The principles of the Declaration of Helsinki were followed in the article.

Availability of data and material

Data openly available in a public repository that issues datasets with DOIs.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

Acknowledgments

We are thankful to the patient for his cooperation and allowing us to use his medical records in our case report.

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