This is a brain tumor that can be benign or malignant. It arises in the supportive (glial) tissue of the brain.
Brain tumors can arise from many different types of cells within the brain, with tumors of the supporting cells more common than nerve cell tumors.
A tumor is named for the cell from which it arises. Tumors derived from astrocytes are called astrocytomas and those from ependymal cells are called ependymomas. Meningiomas are tumors that originate from cells in the linings of the brain called the meninges.
Cerebellar astrocytoma is generally slow-growing and usually does not spread to adjacent tissues or outside the region. Cerebral astrocytoma is found in the upper part of the brain. It may grow slowly (low grade) or rapidly (high grade).
As with most cancers, the cause is not known.
A brain tumor can produce neurologic symptoms and signs in two ways. The first is by increased pressure within the skull. As a tumor grows, it occupies space and causes swelling in the surrounding brain. Since the brain is housed within a rigid and unyielding skull, only a limited amount of tumor mass and swelling is tolerated before symptoms are produced.
The symptoms produced by increased intracranial pressure include:
- Headaches, which are frequently described as pressure at the top of the head behind the eyes. These are usually made worse with exertion, and are most severe at night or early in the morning.
- Nausea, which may be associated with vomiting
- Lethargy, which may progress to the point at which patient spends most of the day sleeping
- Confusion and disorientation
The second category of symptoms are those that occur because of localized brain dysfunction. A tumor may invade or compress the surrounding brain. Depending on the extent or location of the tumor, the normal function of the brain at that location may be impaired. This loss of function may be noticed as numbness or weakness of an arm or a leg, loss of vision, difficulties with speech, and impaired memory and judgment. Such symptoms of neurological deficit can help to determine the location of a tumor.
People with brain tumors often have seizures. They result when the brain produces abnormal electrical activity locally and in the surrounding brain tissue.
Diagnosis is made by medical history including symptoms, physical exam including a neurological exam, and radiological studies such as a head CT (computed tomography) scan or a head MRI (magnetic resonance imaging).
In children, low-grade cerebral astrocytomas can sometimes be cured with complete surgical removal. Radiation is reserved for recurrent tumors.
In adults, these tumors infiltrate the brain and often cannot be completely removed, so radiation therapy is recommended after surgery.
In some centers, radiotherapy is withheld until progression of disease is shown. Chemotherapy may play a role in treatment.
Cerebellar astrocytoma that recurs is treated, if possible, with another surgery. If this is not possible, local radiation is used. If it recurs in an area where it cannot be removed and has already received maximum radiation, chemotherapy may be considered.