Intraventricular Brain Tumors

What are intraventricular tumors? (primary vs secondary)

This distinction matters: primary lesions originate from structures of the ventricular system, whereas secondary lesions extend into the ventricles by contiguity from neighboring anatomic regions.

Intraventricular tumors are broadly categorized as:

• Primary lesions: arising from within the ventricular system.
• Secondary lesions: originating from adjacent parenchyma or neighboring structures and extending into the ventricular space (e.g., pineal region lesions, optic pathway tumors, hypothalamic–pituitary lesions, periventricular gliomas).

Primary lesions can also be grouped into:

• lesions arising from the ependymal lining (e.g., ependymoma, subependymoma, neurocytoma, SEGA, colloid cysts),
• lesions arising from intraventricular structures (e.g., choroid plexus, meningioma of the atrium/trigone, vascular malformations, cysts).

What symptoms can they cause? (hydrocephalus & raised intracranial pressure)

Clinical presentation is largely determined by whether the lesion obstructs normal CSF circulation.

Intraventricular tumors may cause:

• Headache, nausea/vomiting, somnolence, blurred vision — classic features of elevated intracranial pressure.
• Hydrocephalus due to CSF flow obstruction (e.g., foramen of Monro, aqueduct, outlets of the fourth ventricle).
• Focal neurologic deficits depending on location (e.g., memory/alertness disturbances with third-ventricle lesions; cerebellar signs with fourth-ventricle masses).

How is the differential diagnosis made? (location + age + MRI/CT)

A structured clinical framework can dramatically narrow the diagnostic possibilities.

Three variables are typically pivotal in the differential diagnosis of intraventricular brain tumors:

• Location: lateral ventricle (frontal/occipital horn/atrium), third ventricle (anterior or posterior), fourth ventricle.
• Age: pediatric, young adult, or middle/older age.
• Imaging signature: calcifications (CT), cystic components, hemorrhagic features, T1/T2 signal characteristics, and enhancement pattern after contrast.

When specific entities are suspected (e.g., ependymoma), imaging of the entire neuraxis may be recommended to evaluate for additional lesions.

Common intraventricular tumors and imaging features

In Neuroknife’s patient guide, we summarize the most frequent masses involving the ventricular system.

While many tumors have characteristic MRI/CT patterns, the final diagnosis is always made by integrating the clinical context and—when appropriate—histologic confirmation.

Ependymoma

More common in children; classically associated with the fourth ventricle, but it can occur anywhere along the neuraxis.

Ependymoma represents an important proportion of pediatric brain tumors and is frequently located in the fourth ventricle. On CT, calcifications and cystic change may be present. On MRI, lesions often show low T1 signal, high T2 signal, and heterogeneous enhancement after contrast administration.

When clinical and imaging features support a diagnosis consistent with ependymoma, whole-neuraxis imaging (brain and spine) is often performed.

Subependymoma (WHO grade I)

A typically benign, slow-growing lesion that is often discovered incidentally in adults.

Subependymoma is a low-grade tumor (WHO grade I), most commonly diagnosed in the fifth to sixth decade of life. It often appears as a well-circumscribed mass attached to the wall of the fourth ventricle. On MRI, T1 signal is typically iso- to hypointense relative to brain parenchyma, and the lesion characteristically demonstrates minimal or no enhancement after contrast.

Central neurocytoma (WHO grade II)

Typically arises in young adults, often near the foramen of Monro, and may present with signs of increased intracranial pressure.

Central neurocytoma is rare (less than 1% of intracranial tumors) and is most often diagnosed in the second to fourth decade of life. It is frequently located near the foramen of Monro or within the third ventricle. On CT, it may appear hyperdense with punctate calcifications. On MRI, it typically shows heterogeneous enhancement after contrast and may contain small cystic areas.

Gross-total resection is often curative. At Neuroknife, we pursue maximal safe removal while meticulously protecting adjacent neural structures and the venous drainage pathways of the ventricles.

Subependymal Giant Cell Astrocytoma (SEGA) in Tuberous Sclerosis

A benign tumor strongly associated with tuberous sclerosis complex, classically located at the foramen of Monro.

Subependymal giant cell astrocytoma (SEGA) occurs primarily in patients with tuberous sclerosis complex (TSC) and is considered a diagnostic lesion of the syndrome. Tumors most commonly arise at the foramen of Monro and can cause obstructive hydrocephalus. Imaging may show calcifications and, unlike typical subependymal nodules, SEGAs often demonstrate robust enhancement after contrast.

Choroid plexus tumors (papilloma/carcinoma)

These lesions can cause hydrocephalus not only by obstructing CSF pathways, but also by increasing CSF production.

Choroid plexus papillomas (CPP) are typically low-grade tumors, whereas choroid plexus carcinomas are rarer and substantially more aggressive. They often present with hydrocephalus—in many cases due to a combination of CSF hypersecretion and CSF flow obstruction.

On MRI, choroid plexus papilloma commonly demonstrates vivid enhancement after contrast and a characteristic frond-like morphology. Location varies with age: in children, lesions are more often supratentorial; in adults, they are more commonly infratentorial.

In cases where a choroid plexus papilloma is suspected, Neuroknife’s preoperative planning goes beyond confirming morphology. We place particular emphasis on assessing tumor vascularity and defining a hydrocephalus management strategy, as both factors significantly influence operative safety and overall outcome.

Intraventricular meningioma

More commonly diagnosed in middle-aged adults, with a predilection for the atrium/trigone of the lateral ventricle and strong, homogeneous enhancement after contrast.

Intraventricular meningioma is less common than typical extra-axial meningioma, yet it remains one of the more frequent intraventricular brain tumors. Lesions often arise in the atrium (trigone) of the lateral ventricle. On CT/MRI, meningiomas are typically isoattenuating/isointense relative to brain parenchyma and may demonstrate calcifications, along with avid, homogeneous enhancement after contrast.

Surgical access to the atrium of the lateral ventricle requires careful neurosurgical planning, particularly for posterior parietal–occipital lesions. At Neuroknife, corridor selection is guided by detailed anatomic analysis of the lesion and adjacent critical structures, with the goal of minimizing neurologic morbidity while maximizing safety during resection.

Colloid cyst of the third ventricle

A benign cyst in close proximity to the foramen of Monro that can cause acute obstruction and hydrocephalus.

Colloid cysts are benign cystic lesions of the third ventricle, typically closely related to the foramen of Monro. When small, they are often asymptomatic; however, they can cause hydrocephalus, including acute CSF obstruction. On MRI, they are typically well-circumscribed with characteristic T1 signal and lack of contrast enhancement. On CT, they often appear hyperdense, though they may be iso- or hypodense less commonly.

Surgical corridors and endoscopic techniques — when and why?

At Neuroknife, we manage the full spectrum of intraventricular brain tumors using individualized strategy and internationally accepted treatment principles. The surgical approach is determined by lesion location and size, its relationship to venous drainage and critical neuroanatomy, and the therapeutic objective—whether debulking, maximal safe resection, or restoration of CSF flow in the setting of hydrocephalus.

The principal surgical approaches for intraventricular lesions include:

• Transcallosal (ventricular entry via the corpus callosum): often useful for lesions in the anterior two-thirds of the lateral ventricle and anterior third-ventricle lesions.
• Transcortical approach (ventricular entry through the cerebral cortex): an alternative corridor requiring a small cortical incision; selection is careful and individualized.
• Endoscopic techniques: most commonly for biopsy and management of hydrocephalus (e.g., endoscopic third ventriculostomy). In selected intraventricular lesions, endoscopy may also enable complete removal.
• Suboccipital approaches for fourth-ventricle tumors (midline or lateral, depending on anatomy).

As a guiding principle at Neuroknife, our goal is not merely tumor removal, but maximal safety: achieving the appropriate extent of resection when indicated while protecting critical neuroanatomy and restoring physiologic CSF circulation when hydrocephalus is present. Surgical strategy is tailored so that oncologic objectives are pursued without compromising function and quality of life.