Posterior fossa ependymoma is a rare brain tumor primarily affecting children. It originates in the central nervous system from specialized cells that line the brain’s fluid-filled spaces within the posterior fossa, an area at the back of the skull. While uncommon, it represents a significant concern due to its location and impact on neurological function.
What is Posterior Fossa Ependymoma?
Ependymomas are tumors that arise from ependymal cells, which are cells lining the ventricles of the brain and the central canal of the spinal cord. These cells are involved in producing cerebrospinal fluid (CSF), which cushions and protects the brain and spinal cord. The “posterior fossa” refers to the area at the back of the skull, housing critical structures like the cerebellum and brainstem. In children, the majority of ependymomas, around 70%, are found in this posterior fossa region.
Ependymomas are classified into different grades based on their characteristics under a microscope and how quickly they tend to grow. The World Health Organization (WHO) categorizes ependymomas from Grade 1 to Grade 3. Grade 1 tumors, such as subependymomas, are typically slow-growing and often benign, while Grade 3 ependymomas, referred to as anaplastic ependymomas, are malignant and fast-growing. While historically, Grade III was considered the most common in the posterior fossa, the 2021 WHO classification now emphasizes molecular subtypes, such as Posterior Fossa Group A (PFA) and Group B (PFB), which offer more precise prognostic information. PFA ependymomas are more common in young children and are generally more aggressive, whereas PFB tumors tend to occur in older children and adolescents with more favorable outcomes.
Identifying Potential Indicators
The symptoms associated with posterior fossa ependymoma can vary significantly, depending on the child’s age and the tumor’s size and exact location. These tumors often manifest symptoms due to their position within the posterior fossa, which can obstruct the normal flow of cerebrospinal fluid (CSF). This blockage leads to a buildup of fluid in the brain, a condition known as hydrocephalus, which increases pressure inside the skull.
Common indicators include headaches, which are frequently worse in the morning or may awaken the child from sleep. Nausea and vomiting are also prevalent, often occurring without an apparent cause. The tumor’s impact on the cerebellum can lead to balance issues, an unsteady gait (ataxia), and problems with coordination. Vision changes, such as double vision or issues with eye movement, may also be observed. In infants, an enlarging head circumference, irritability, or a persistent head tilt (torticollis) can be signs of increased intracranial pressure.
Confirming a Diagnosis
The diagnostic process typically begins with a thorough neurological examination. This assessment evaluates a child’s reflexes, balance, coordination, vision, and other neurological functions, providing initial clues about the presence and location of a tumor. If a tumor is suspected, imaging studies are the next important step.
Magnetic Resonance Imaging (MRI) of the brain and spine is the primary and most effective diagnostic tool. MRI scans provide detailed images of brain structures, revealing the tumor’s size, location, and characteristics, and identifying if it has spread within the central nervous system. A tissue sample, or biopsy, is essential for definitive diagnosis and grading. This surgical procedure allows pathologists to examine tumor cells under a microscope, determining the specific type and grade. In some cases, a lumbar puncture (spinal tap) may be performed to collect cerebrospinal fluid for analysis, checking for tumor cells which may indicate potential spread, particularly in higher-grade tumors.
Approaches to Treatment
Treating posterior fossa ependymoma involves a multidisciplinary approach, often combining several therapies to achieve the best possible outcome. Surgical resection is the cornerstone of treatment, aiming for maximal safe resection—removing as much of the tumor as safely possible without causing new neurological deficits. Complete tumor removal, or gross total resection, is a significant predictor of positive outcomes and improved survival rates for patients. Even if the entire tumor cannot be removed, partial removal can relieve pressure and reduce symptoms.
Following surgery, radiation therapy plays a crucial role, especially for residual tumor or higher-grade ependymomas. Radiation targets any remaining tumor cells to prevent recurrence and improve long-term control of the disease. It is often administered to the tumor bed, as microscopic tumor cells are believed to remain even after a seemingly complete removal. The timing and dosage of radiation are carefully planned, particularly in young children, to minimize potential long-term side effects on developing brains.
Chemotherapy’s role in treating ependymoma is limited compared to other brain tumors due to its limited effectiveness against these specific tumor cells. However, it may be used in specific situations, such as for very young children where radiation might be delayed, or in clinical trials exploring new therapeutic strategies. Ongoing research continues to explore more effective systemic treatments for ependymoma.
Post-Treatment Management
After the primary treatment for posterior fossa ependymoma, ongoing management is crucial for monitoring recovery and detecting any potential recurrence. Regular follow-up appointments are a standard part of this long-term care. These appointments typically include comprehensive neurological examinations to assess the child’s neurological function and track any changes.
Surveillance Magnetic Resonance Imaging (MRI) scans of the brain and spine are performed periodically. These scans are vital for monitoring the tumor site for any signs of regrowth or the development of new tumors. The frequency of these scans is usually higher in the initial years following treatment and may decrease over time if the child remains stable. Beyond medical monitoring, ongoing supportive care is often necessary to address any long-term effects resulting from the tumor or its treatment, including physical therapy to improve strength and coordination, occupational therapy to assist with daily living activities, and speech therapy for communication challenges. Such rehabilitation services are tailored to the individual needs of each child, aiming to optimize their functional abilities and overall quality of life.