Ependymoma is a tumor that arises from the ependymal cells lining the fluid-filled spaces of the central nervous system, which includes the brain and spinal cord. As a type of glioma, this tumor is relatively uncommon, accounting for approximately 9% of all central nervous system tumors in children and about 2% in adults. Ependymomas can occur at any age, but they are most frequently diagnosed in young children, often under the age of five, with a second peak in diagnosis occurring in middle-aged adults. The specific location of the tumor profoundly influences the symptoms experienced, the required treatment plan, and the overall outlook for the patient.
Defining Ependymoma: Origin, Location, and Rarity
Ependymomas originate from specialized glial cells called ependymal cells. These cells line the ventricles of the brain and the central canal of the spinal cord, forming the boundary of the spaces where cerebrospinal fluid (CSF) circulates. The tumors are highly heterogeneous, exhibiting significant variability in behavior based on their location.
The anatomical location is a primary factor in classifying and treating this tumor type, with three main compartments being recognized: supratentorial, infratentorial, and spinal. Supratentorial ependymomas develop in the upper two-thirds of the brain, including the cerebral hemispheres and the lateral or third ventricles. Infratentorial tumors, also called posterior fossa ependymomas, are located in the lower third of the brain, including the brainstem, cerebellum, and the fourth ventricle.
Spinal ependymomas are more common in adults than in children and typically arise in the spinal cord itself, especially in the lower lumbar and sacral regions. The overall rarity of ependymoma means that specific risk factors or causes are not well-established, though a small number of cases are associated with genetic conditions like Neurofibromatosis type 2 (NF2). The location of the tumor has been found to be a more significant factor in predicting the tumor’s behavior than its microscopic appearance alone.
Recognizing the Signs: Symptoms Based on Tumor Location
Symptoms of an ependymoma are directly tied to the tumor’s location and the pressure it exerts on surrounding neural tissue. Infratentorial tumors often cause symptoms related to hydrocephalus, a buildup of cerebrospinal fluid. This blockage increases pressure inside the skull, frequently presenting as headaches, nausea, and vomiting.
These pressure headaches are often most pronounced in the morning or upon waking. Pressure on the cerebellum, which controls movement, can also lead to issues with coordination and balance, such as an unsteady gait or dizziness. In very young children, the pressure may present as an abnormally enlarged head size since their skull sutures have not yet fused.
Supratentorial ependymomas, located in the cerebrum, manifest with focal neurological deficits depending on the affected area. Common symptoms include seizures, motor weakness on one side of the body, or changes in cognitive function. Impact on the cerebral hemispheres can also lead to personality changes or difficulty with speech and language.
Spinal cord ependymomas generally cause symptoms that progress gradually, resulting from compression of the spinal nerves or the cord itself. Patients may experience localized pain in the neck or back, along with numbness, tingling, or weakness in the limbs or trunk. Tumors in the lower spinal cord can specifically affect bladder and bowel control.
Medical Confirmation: Diagnosis and WHO Classification
Diagnosis begins with imaging studies, primarily Magnetic Resonance Imaging (MRI), used for initial screening and determining the tumor’s size and exact location. MRI scans often reveal a well-defined mass that brightens when a contrast dye is administered, detailing the tumor’s relationship to surrounding structures. Imaging alone, however, cannot provide a definitive diagnosis or predict the tumor’s behavior.
A definitive diagnosis requires a tissue biopsy, where a sample of the tumor is surgically removed for pathological examination. This analysis classifies the tumor using the World Health Organization (WHO) grading system. Ependymomas are grouped into three grades: Grade I (slow-growing subtypes like subependymoma), Grade II (classic ependymoma), and Grade III (anaplastic ependymoma, characterized by faster growth).
The modern classification, updated in 2021, emphasizes molecular profiling alongside traditional microscopic grading. Tumor tissue is routinely analyzed for specific genetic and epigenetic features, such as DNA methylation patterns and gene fusions. These features are now recognized as having a stronger link to prognosis than grade alone. For instance, posterior fossa ependymomas are molecularly divided into Group A (PF-A) and Group B (PF-B), with PF-A generally having a less favorable outlook. This detailed information helps stratify the disease and guides subsequent treatment intensity.
Primary Treatment Approaches
Treatment centers on surgical removal of the tumor, which is the most important factor influencing long-term outcome. The neurosurgical goal is Gross Total Resection (GTR), meaning the entire visible tumor is removed. Achieving GTR depends heavily on the tumor’s location, especially if it is near delicate structures like the brainstem.
Even after GTR, surgery is almost always followed by adjuvant therapy to eliminate remaining microscopic disease. Radiation therapy is a standard part of the treatment plan for most ependymomas, especially for higher-grade tumors or incomplete surgical resection. Radiation involves directing high-energy beams to the tumor site to destroy residual cells.
For children, specialized techniques like proton therapy may be preferred. This technique delivers a precise dose of radiation while minimizing damage to surrounding healthy, developing tissue. The typical radiation dose delivered to the tumor bed is 54 to 59.4 Gray, administered in fractions over several weeks. Radiation is also used for spinal ependymomas, especially if they are Grade III or not fully removed.
Chemotherapy has a limited role compared to other brain tumors and is not considered a primary treatment for localized disease. Its main use is in very young children (typically under 18 months of age). Chemotherapy may be administered to temporarily control tumor growth, delaying the need for radiation therapy until the child’s developing brain is less vulnerable to long-term side effects.