Ependymoma
Ependymomas are glial tumors (glial cells are the supporting cells of the brain and spinal cord and ependymal cells are a subtype of glial cells) that originate from the ependymal cells that line ventricles of the brain and central canal of the spinal cord. The ventricles and central canal are naturally occurring cavities within the brain where cerebrospinal fluid is normally produced. Epenymomas usually arise from the ependymal tissue on the floor of the 4th ventricle in children or in the spinal cord in adults. They can also arise in a variety of other locations throughout the brain and spine. Epenymomas often lead to obstruction of the cerebrospinal fluid flow within the brain because of their intimate relationship with the ventricles, central canal and spinal fluid.
Ependymomas are sub-divided and pathologically graded into four major types: subependymomas and myxopapillary ependymomas (grade I), and ependymomas (grade II) and anaplastic ependymomas (grade III). The grade is based on how much the cells look like normal ependymal cells, although various grading systems exist. The cells of a grade I ependymal tumor look somewhat unusual, and those of a grade III tumor appear pleomorphic and more invasive to the surrounding tissue.
- Subependymomas usually occur along the walls of a ventricle and are slow growing and considered to be low-grade or grade I tumors.
- Myxopapillary ependymomas tend to occur in the lower part of the spinal cord near the conus medullaris, which is essentially the tail end of the spinal cord. This part of the spinal cord is important in controlling bowel and bladder function as well as some lower extremity function. Both of these ependymoma subtypes are slow growing and are considered to be low-grade or grade I tumors.
- Ependymomasare the most common ependymal tumors and are considered grade II tumors. These tumors are usually located along or adjacent to the ventricular system and often in the 4th ventricle near the brain stem and the upper portions of the spinal cord. These tumors can often lead to hydrocephalus where there is a backup of the spinal fluid within the venrticles of the brain.
- Anaplastic ependymomas are high-grade tumors (grade III) and tend to be faster growing than the lower grade ependymal tumors. Similar to grade-II ependymomas, these are often located along or adjacent to the ventricular system and often in the 4th ventricle near the brain stem and the upper portions of the spinal cord.
Symptoms
The initial symptoms of brain tumors, such as headache and nausea, usually are the result of increased intracranial pressure caused by the bulk of the tumor or a backup of the cerebrospinal fluid that surrounds the brain and spinal cord. Ependymal cells are widely distributed throughout the central nervous system, so these tumors can occur in a variety of locations and can cause a wide variety of other symptoms. Depending on the location of the mass they may cause seizures, gait difficulties, balance problems, neck pain, double vision and weakness or numbness in the limbs. Some tumors located in the spinal cord can cause difficulty with bladder or bowel control.
Diagnosis
In general, the initial treatment of an ependymoma is surgical resection of as much of the tumor as possible. With modern techniques, surgery for a craniotomy (making an opening in the skull) is generally safe and allows the team at the Brain Tumor Center to obtain tumor tissue for accurate microscopic diagnosis and treatment planning. Depending on the location of the tumor the surgeon can often achieve a gross or near total removal of the tumor when evaluated with an MRI scan after surgery. Removing the tumor and reliving any hydrocephalus tends to reduce the symptoms caused by the presence of the tumor. In some cases, depending on the location of the ependymoma, the neurosurgeon may employ techniques that enable safe removal of a tumor even along the brain stem.
Some of these techniques include intra-operative neuro-monitoring, where the function of the nerves that emanate out of the brain stem or spinal cord are monitored throughout the operation in order to make sure vital brainstem and spinal cord functions are not disrupted. In other locations of the brain the surgeon may employ stereotactic image-guided techniques where the surgeon uses an MRI based 3D model of the patient’s brain – much like a GPS system – to safely remove as much of the tumor as possible. High-powered microscopes are also used to help the neurosurgeon better see the tumor and ultrasonic aspirators are sometimes used to help remove the tumor.
Most grade I tumors do not recur after complete surgical removal. Grades II and III tumors need additional treatment and have a higher likelihood of recurring. Radiation therapy is sometimes recommended for older children and adults following surgery if all visible tumor wasn’t removed and in some cases even after complete resection. If the tumor is localized, radiation therapy is usually given just to that area of the brain. If the tumor has spread to the spinal fluid, radiation is usually also given to the entire brain and spine in addition to where the tumor started.
After surgery, each patient is reviewed at our Multi-Disciplinary Tumor Board with an expert team of neuro-oncologists, medical oncologists, neuro-pathologists, neuro-radiologists and neurosurgeons. Together the tumor board recommends the best treatment options for each patient, incorporating ongoing national clinical trials and the latest treatment protocols.