Ependymomas are slow-growing tumors of the central nervous system. They are classified as gliomas and account for 2–6% of glioma cases. Ependymomas usually grow into the cerebral ventricles. They may remain completely asymptomatic, cause local neurological deficits, or cause life-threatening cerebrospinal fluid outflow obstruction by blocking the cerebrospinal fluid pathways. The treatment of choice is microsurgical resection. The ideal goal is complete resection, but this is not always possible in certain regions of the brain. Therefore, additional radiation or chemotherapy is often necessary to prevent subsequent tumor growth.
In principle, ependymomas can occur in any age group and in the entire area of the ventricular system as well as the spinal cord. However, they are diagnosed more frequently in childhood and adolescence (25% in children under 3 years of age). Almost two-thirds of ependymomas located in the skull occur in children, while tumors occurring in the spinal cord are diagnosed almost exclusively in adults or adolescents. In addition to the age peak in children, ependymomas in adults are more commonly found between the ages of 30 and 60.
The group of ependymomas is very heterogeneous and includes benign, slow-growing tumors, but also aggressive, anaplastic tumors. In addition, there are different molecular subgroups, which are associated with different prognoses.
Histologically, ependymomas are divided into WHO grades I–III. They are subdivided into four subgroups according to the WHO classification.
- Subependymomas (WHO I)
- Myxopapillary ependymomas (WHO I)
- Ependymomas (WHO II)
- Anaplastic ependymomas (WHO III)
While myxopapillary ependymomas (WHO I) occur more frequently with adults, anaplastic ependymomas (WHO III) occur particularly with children. Anaplastic ependymomas (WHO grade III) are aggressive and associated with a high risk of recurrence. This means that this type of tumor often grows again.
- Depending on the speed of their growth, ependymomas growing in the brain can lead to a blockage of the cerebrospinal fluid outflow in the ventricular system and thus to occlusive hydrocephalus. This results in an increase in pressure in the ventricular system, which can lead to headaches, nausea, vomiting, unsteady gait and clouding of consciousness, even coma.
- Furthermore, ependymomas can lead to facial, pharyngeal and ocular muscle deficits due to the involvement of cranial nerves.
- With babies, an ependymoma can manifest itself in an enlargement of the skull circumference (macrocephaly) and a bulging and tense fontanel due to the unclosed cranial sutures. This often occurs before the child shows other symptoms such as developmental delay, nausea or vomiting.
- For intramedullary ependymomas in the spinal cord, symptoms usually begin in early adulthood, with patients primarily complaining of localized, non-radiating back pain. Furthermore, about half of the patients have sensory disturbances and motor deficits at the time of diagnosis.
- Spinal movement disorder (ataxia) with tumor growth in the neck and cervical region as well as a bladder or bowel dysfunctionoccur rarely.
In imaging diagnostics, ependymomas typically appear as a heterogeneous mass with solid or necrotic or cystic parts, whereby hemorrhages and calcifications are not uncommon.
The imaging diagnosis is made by magnetic resonance imaging (MRI).
To exclude possible metastases, an imaging examination of the entire central nervous system including the spinal cord must always be performed.
In up to 10 % of patients, tumor cells may seed in the cerebrospinal fluid system. This is referred to as drop metastases. Therefore, an additional lumbar puncture must be performed for cytological detection of tumor cells.
Due to its high prognostic significance, the therapy of choice is the complete surgical removal of the ependymoma, although this is not always possible. Subsequent supportive radiotherapy is adapted to the individual patient and depends on the following factors;
- extent of tumor resection
- histological findings
- age of the patient
- general condition and medical history
- possible tumor seeding
- patient's tolerance to follow-up treatment
In some cases, it is not possible to remove the tumor completely because it has grown into vital structures such as the brain stem. Here, radiotherapy is an alternative treatment. Radiotherapy is also used for recurrences, regardless of the degree of malignancy.
If a perfect cerebrospinal fluid outflow cannot be restored by a maximum and safe tumor resection, a follow-up operation is required in rare cases, in which a ventriculoperitoneal shunt is inserted for alternative drainage of the cerebrospinal fluid.
Depending on the location of the tumor, there is a certain risk for neighboring structures to be damaged during surgery. The posterior fossa syndrome with cerebellar mutism after infratentorial surgery in children is particularly worth mentioning here. In addition, there is always the risk of so-called villi being torn off during surgery, which surround the surface of the tumor like cauliflowers. In this case, drop metastases can form.
In order to be able to resect the tumor completely and keep the risk of complications as low as possible, we use special procedures at Inselspital such as intraoperative imaging with MRI or fluorescent dyes, neuronavigation, intraoperative special neuromonitoring and other techniques.
In general, the complication rate of both tumor surgery and radiotherapy is influenced by many factors. Size and location of the tumor, its accessibility as well as the clinical condition and age of the patient are to be emphasized here.
Besides the histological grading according to the WHO classification and the molecular subtypes of the tumor, complete surgical removal is the most important prognostic factor. Since anaplastic ependymomas (WHO grade III) as well as the unfavorable tumor localization in the posterior fossa are significantly more common in children, adult patients have a better prognosis.
The 5-year survival rate in children therefore varies between 50% and 75%, although mortality is significantly increased if the tumor is already recurrent. Supportive radiotherapy can reduce the recurrence rate, especially in cases of incomplete tumor removal.
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