Pediatric intraventricular meningioma: A series of six cases.

OBJECTIVE: Meningiomas in children is a rare occurrence. Primary intraventricular meningiomas (IVMs) are even rarer with reported incidence of 0.5%-5% of all meningiomas. The aim of the study was to describe the demographic profile, location, surgical approach, complications, and histopathology of six pediatric patients with IVM.
MATERIALS AND METHODS: We retrospectively analyzed all intraventricular tumors operated at our Institute from January 2010 till July 2015. Patients' clinical details and follow-up were obtained from hospital records and scans were obtained from picture archiving and communication system.
RESULTS: We found 6 pediatric patients (age ≤18 years) with histopathologically proven IVM. The mean age in this series was 14.6 years. Tumor was most commonly approached through the superior parietal lobule in this series. Gross total excision was achieved in all patients. The blood loss in the series was in the range of 600-2000 ml with a mean of 1100 ml. All were grade 1 meningioma on histopathological examination. Transitional meningioma was the most common histological subtype. None of the patients had a recurrence at last follow-up.
CONCLUSIONS: Pediatric IVMs are rare tumors. They tend to have a male preponderance in contrast to adults which have a preference for females. Parietooccipital transcortical, transcallosal approach, middle/inferior temporal gyrus approach are the described techniques to tackle such tumors depending on the location of such tumors. Surgeons should watch out for massive blood loss during surgery, especially via the parietooccipital transcortical approach.

Introduction

Meningiomas in children are a rare occurrence. They comprise approximately 3% of all pediatric brain tumors.[1] Primary intraventricular meningiomas (IVMs) are even rarer with reported incidence of 0.5%–5% of all meningiomas. IVM arise from arachnoid cap cells embedded in choroid plexus. Most commonly they are located in the lateral ventricle, followed by third ventricle and rarely in the fourth ventricle.[2] Lateral ventricle meningioma usually presents with symptoms of raised intracranial pressure and can attain significant size before being detected. Meningiomas of the third and fourth ventricle present with obstructive hydrocephalus. Treatment modalities include observation, stereotactic radiosurgery, or surgical excision. We describe a series of 6 pediatric patients with IVM managed surgically in our institute.

Materials And Methods

We retrospectively analyzed all intraventricular tumors operated at our institute from January 2010 to July 2015. Patients' clinical details and follow-up were obtained from hospital records and scans were obtained from picture archiving and communication system. The presentation, radiology, surgical approach, intraoperative events, histopathology and follow-up of all the patients was analyzed.

Results

We found six pediatric patients (age ≤18 years) with histopathologically proven IVM. Case details of all patients are summarized in Table 1. The mean age in this series was 14.6 years with minimum age being 8 years and two patients of age 18 years. Male:female ratio of patient distribution was 2:1 in this series. Three patients were operated via the superior parietal lobule, one patient via transcallosal approach, one patient via middle temporal gyrus. One patient underwent surgery outside and presented with a persistent headache, visual deterioration. Imaging revealed residual tumor and chronic bifrontal extradural hematoma (EDH). The patient underwent bifrontal craniotomy, evacuation of EDH, and tumor excision via transcortical approach. Gross total excision was achieved in all patients. The blood loss in the series was in the range of 600–2000 ml with a mean of 1100 ml. All were grade 1 meningioma on histopathological examination. Transitional meningioma was the most common histological subtype. All patients had imaging within 6 months. None of the patients had a recurrence at last follow-up. Figures 1–3 reveal the preoperative images, immediate postoperative scan after 4 h and follow-up scan at 6 months respectively of an 8-year-old male child with left lateral ventricle meningioma.

Table 1

The symptoms, surgical approach, complications, and follow-up of all six cases in the series

Figure 1

(a) Noncontrast computed tomography head axial sections showing well defined hyperdense lesion in left lateral ventricle with perilesional edema (b) Contrast enhanced CT head (axial sections) of the above patient showing enhancement of the intraventricular lesion with mass effect and midline shift

Figure 3

Contrast enhanced magnetic resonance imaging brain axial section at 6 month follow-up showing postoperative changes with no evidence of residual tumor

Postoperative noncontrast computed tomography head axial sections showing postoperative changes with pneumoventricle and no residual tumor

Discussion

Meningiomas arise from arachnoid cap cells. IVMs arise from arachnoid cap cells in choroid plexus. The third ventricle meningiomas arise from tela of velum interpositum whereas the fourth ventricle from the choroids or inner tela choroidea.[3] The incidence of pediatric IVM is low and few series exist in literature. There was a male preponderance in our series. This is in concordance with the existing literature which favors a slight male preponderance for pediatric intracranial meningiomas.[4] Five out of six patients had solitary IVM whereas one patient had multiple meningiomas with bilateral acoustic schwannoma as a manifestation of neurofibromatosis-2. IVM do not present with a specific clinical syndrome. In 1938, Cushing and Eisenhardt[5] defined five clinical features of trigonal meningiomas (1) pressure symptoms (often unilateral headache), (2) contralateral homonymous hemianopia (frequently macula splitting), (3) contralateral sensorimotor deficit (sensory involvement greater than motor involvement and sometimes trigeminal involvement), (4) cerebellar affection (>50%), and (5) dysphasic and paralexic disturbance in left-sided tumors.

A headache was the most common presenting symptom. Symptoms may be ascribed to raise intracranial pressure as a result of tumor, ventricular dilatation, surrounding edema, and compression of adjacent normal brain parenchyma. IVM appear hyperdense on computed tomography with or without areas of calcification,[6] isointense to hypointense on T1-weighted images, intense enhancement on postgadolinium scans.[7] Varying extent of temporal horn dilatation and peritumoral edema were seen. An angiogram was not performed in any of the patients. The vascular supply of IVM comes from anterior, and lateral posterior choroidal arteries and both are not suitable for embolization. Incidental IVM without perilesional edema, temporal horn dilatation can be followed up with serial imaging. Meningioma being a benign tumor with excellent outcomes following surgical excision is best managed through surgical excision. Radiosurgery is a viable option in patients who are not fit for general anesthesia or who refuse consent for surgery. However, the intraventricular location may pose challenges for this modality of treatment.[2] We have used three surgical corridors which are well described in literature. One patient was operated via the middle temporal gyrus approach. This approach has the shortest trajectory, granting an early control of the feeding vessels.[8] Other approaches described are via the inferior temporal gyrus, collateral sulcus, and the occipitotemporal gyrus. Image guidance is of great help in defining the site of corticectomy. Tumors in three patients were approached via the superior parietal lobule which is well described and commonly used.[9] This was chosen for larger tumors predominantly in the atrium. The superior parietal lobule approach although seem to have a longer trajectory; the distance becomes actually shorter when tumor grows superiorly and enlarges the atrium. The superior parietal lobule approach prevents damage to the optic radiations which occur in a middle temporal gyrus approach. In the superior parietal lobule approach, the feeding vessels are encountered after much tumor has been resected. This explains the high blood loss in our series. One of the patients had intraoperative hypotension during surgery as a result of massive blood loss. Fornari et al.[7] have suggested a sagittal paramedian incision of the parietal cortex at a distance of 4 cm from the midline that starts 1 cm behind the postcentral fissure and is continued for 4–5 cm as far as the parietooccipital fissure. This approach is supposed to be less harmful with regards to damage to the optic radiation.

A significant limitation of our study is the lack of visual perimetry both in the pre- and post-operative period. No fresh neurological deficits were observed in the postoperative period in any of our patients. Anterior transcallosal approach was used in one of our patient in which tumor was localized to the third ventricle and frontal horn of lateral ventricle.

Conclusion

Pediatric IVMs are rare tumors. They tend to have a male preponderance in contrast to adults which have a preference for females. Symptomatic IVM should be surgically excised. Parietooccipital transcortical, transcallosal approach, middle/inferior temporal gyrus approach are the described techniques to tackle such tumors depending on the location of such tumors. Surgeons should watch out for massive blood loss during surgery, especially via the parietooccipital transcortical approach.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.