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The growth of abnormal
cells in the tissues of the brain. Brain tumors can be benign (not
cancer) or malignant (cancer).
Signs and Symptoms
The symptoms of brain tumors depend on their size and location in the
brain. Symptoms often are caused by damage to vital tissue and pressure
on the brain as the tumor grows within the limited space in the skull.
They may be caused by swelling and a buildup of fluid around the tumor,
a condition called edema. Symptoms also may be due to hydrocephalus,
which occurs when the tumor blocks the flow of cerebrospinal fluid and
causes a build-up in the ventricles. If a brain tumor grows very slowly,
its symptoms may not appear for some time.
The most frequent symptoms of brain tumors include:
* Headaches that tend to be worse in the morning and ease during the day
* Seizures or convulsions
* Nausea or vomiting
* Weakness or loss of feeling in the arms or legs
* Stumbling or lack of coordination in walking
* Abnormal eye movements or changes in vision
* Drowsiness
* Changes in personality or memory
* Changes in speech
These symptoms may be caused by brain tumors or by other problems.
Diagnostic tests can be performed to determine if the cause of your
symptoms is a brain tumor and if it is a primary or secondary one.
Primary Brain Tumors
Tumors that begin in brain tissue are known as primary brain tumors and
are classified by the type of tissue in which they originate. The most
common brain tumors are gliomas, which begin in the glial or supportive
tissue. There are several types of gliomas:
* Astrocytomas — These tumors arise from small, star-shaped cells
called astrocytes. They may grow anywhere in the brain or spinal cord.
In adults, astrocytomas most often arise in the cerebrum. In children,
they occur in the brain stem, the cerebrum and the cerebellum. A grade
III astrocytoma is sometimes called anaplastic astrocytoma. A grade IV
astrocytoma is usually called glioblastoma multiforme.
* Brain stem gliomas — These tumors occur in the lowest,
stem-like part of the brain. The brain stem controls many vital
functions. Most brain stem gliomas are high-grade astrocytomas.
* Ependymomas — These tumors usually develop in the lining of the
ventricles. They may also occur in the spinal cord. Although these
tumors can develop at any age, they are most common in childhood and
adolescence.
* Oligodendrogliomas — These tumors occur in the cells that
produce myelin, the fatty covering that protects nerves. These tumors
usually arise in the cerebrum. They are rare, grow slowly and usually do
not spread into surrounding brain tissue. They occur most often in
middle-aged adults but have been found in people of all ages.
There are other types of brain tumors that do not begin in glial tissue.
Some of the most common are described below:
* Medulloblastomas — These tumors were once thought to develop
from glial cells. However, recent research suggests that these tumors
develop from primitive or developing nerve cells that normally do not
remain in the body after birth. For this reason, medulloblastomas are
sometimes called primitive neuroectodermal tumors (PNET). Most
medulloblastomas arise in the cerebellum; however, they may occur in
other areas as well. These tumors occur most often in children and are
more common in boys than in girls.
* Meningiomas — These tumors grow from the meninges, or membranes
that enclose the brain and spinal cord. They are usually benign. Because
these tumors grow very slowly, the brain may be able to adjust to their
presence. Meningiomas often grow quite large before they cause symptoms.
They occur most often in women between 30 and 50 years of age.
* Schwannomas — These tumors are benign and begin in Schwann
cells, which produce the myelin that protects the acoustic nerve, or the
nerve of hearing. They occur mainly in adults. These tumors affect women
twice as often as men.
* Craniopharyngiomas — These tumors develop in the region of the
pituitary gland near the hypothalamus. They are usually benign but are
sometimes considered malignant because they can press on or damage the
hypothalamus, a region of the brain, and affect vital functions. These
tumors occur most often in children and adolescents.
* Germ cell tumors — These tumors arise from developing sex cells
or germ cells. The most frequent type of germ cell tumor in the brain is
the germinoma.
* Pineal region tumors — These tumors occur in or around the
pineal gland, a tiny organ near the center of the brain. The tumor can
be slow growing (pineocytoma), or fast growing (pineoblastoma). The
pineal region is very difficult to reach, and these tumors often cannot
be removed.
Secondary Brain Tumors
Metastasis is the spread of cancer. Cancer that begins in other parts of
the body may spread to the brain and cause secondary tumors. These
tumors are not the same as primary brain tumors. Cancer that spreads to
the brain is the same disease and has the same name as the original or
primary cancer. For example, if lung cancer spreads to the brain, the
disease is called metastatic lung cancer because the cells in the
secondary tumor resemble abnormal lung cells, not abnormal brain cells.
Treatment for secondary brain tumors depends on where the cancer started
and the extent of the spread as well as other factors, including the
patient's age, general health and response to previous treatment.
Diagnosis and Tests
To find the cause of your symptoms, your doctor will ask about your
personal and family medical history and perform a complete physical
examination. In addition to checking general signs of health, your
doctor will perform a neurologic exam. This includes checks for
alertness, muscle strength, coordination, reflexes and response to pain.
Your doctor also examines the eyes to look for swelling caused by a
tumor pressing on the nerve that connects the eye and the brain.
Depending on the results of the physical and neurologic examinations,
your doctor may request one or both of the following:
* Computerized Tomography (CT): Computerized tomography (CT) or
computerized axial tomography (CAT) scan is a series of detailed
pictures of the brain, created by a computer linked to an X-ray machine.
In some cases, a special dye is injected into a vein before the scan.
The dye helps to show differences in the tissues of the brain.
* Magnetic Resonance Imaging (MRI): Magnetic resonance imaging (MR)
provides pictures of the brain, using a powerful magnet linked to a
computer. MRI is especially useful in diagnosing brain tumors because it
can "see" through the bones of the skull to the tissue underneath. A
special dye may be used to enhance the likelihood of detecting a brain
tumor.
The doctor may also request other tests such as:
* Angiogram or Arteriogram: These tests are a series of X-rays
taken after a special dye is injected into an artery, usually in the
area where the abdomen joins the top of the leg. The dye, which flows
through the blood vessels of the brain, can be seen on X-rays. These
X-rays can show the tumor and connecting blood vessels.
* Brain Scan: A brain scan reveals areas of abnormal growth in
the brain and records them on special film. A small amount of a
radioactive material is injected into a vein. This dye is absorbed by
the tumor and the growth shows up on the film. The radiation leaves the
body within 6 hours and is not dangerous.
* Functional Imaging: This test utilizes MRI or magnetic source
imaging to identify functional pathways in the brain (motor, visual,
language) and alerts the surgeon to potential injury to these pathways
during surgery before damage could occur.
* Myelogram: A myelogram, sometimes called a lumbosacral spine
X-ray , is an X-ray or computerized tomography (CT) scan of the spine. A
special dye is injected into the cerebrospinal fluid in the spine and
the patient is tilted to allow the dye to mix with the fluid. This test
may be done when the doctor suspects a tumor in the spinal cord.
* MR Spectroscopy: This is a modified MRI scan that shows
metabolic activity within a brain tumor. This has largely replaced
positron emission tomography (PET) scanning due to its superior
resolution and accuracy.
Treatment
Treatment for brain tumors depends on a number of factors
including the
type, location and size of the tumor as well as the patient's age and
general health. Treatment methods and schedules differ for children and
adults.
Brain tumors are treated with surgery, radiation therapy and
chemotherapy. Our doctors also are studying a vaccine for treating a
recurrent cancer of the central nervous system that occurs primarily in
the brain, known as glioma.
Depending on your needs, several methods may be used. Our team includes
neurosurgeons, medical oncologists, radiation oncologists, nurses, a
dietitian and a social worker, who work together to provide the best
possible care.
Before treatment begins, most patients are given steroids, drugs that
relieve swelling or edema. Your may receive anticonvulsant medicine to
prevent or control seizures. If hydrocephalus is present, you may need a
shunt to drain cerebrospinal fluid. A shunt is a long, thin tube placed
in a ventricle of the brain and then threaded under the skin to another
part of the body, usually the abdomen. It works like a drainpipe. Excess
fluid is carried away from the brain and is absorbed in the abdomen. In
some cases, the fluid is drained into the heart.
Surgery
Surgery is the usual treatment for most brain tumors. To remove a brain
tumor, a neurosurgeon makes an opening in the skull. This operation is
called a craniotomy. Whenever possible, the surgeon attempts to remove
the entire tumor. If the tumor cannot be completely removed without
damaging vital brain tissue, your doctor may remove as much of the tumor
as possible. Partial removal helps to relieve symptoms by reducing
pressure on the brain and reduces the amount of tumor to be treated by
radiation therapy or chemotherapy.
Some tumors cannot be removed. In such cases, your doctor may do only a
biopsy. A small piece of the tumor is removed so that a pathologist can
examine it under a microscope to determine the type of cells it
contains. This helps your doctor decide which treatment to use.
Sometimes, a biopsy is done with a needle. Doctors use a special head
frame (like a halo) and ) CT scans or MRI to pinpoint the exact location
of the tumor. The surgeon makes a small hole in the skull and then
guides a needle to the tumor. Using this technique to do a biopsy or for
treatment is called stereotaxis. Other advanced techniques during
surgery include brain mapping to find functional pathways near tumors,
endoscopy to perform biopsies and open spinal fluid pathways through a
small scope and advanced frameless stereotaxic computer assisted tumor
resections. Intraoperative MRI also is available to help maximize tumor
removal.
Radiation therapy
Radiation therapy, also called radiotherapy, is the use of high-powered
rays to damage cancer cells and stop them from growing. It is often used
to destroy tumor tissue that cannot be removed with surgery or to kill
cancer cells that may remain after surgery. Radiation therapy also is
used when surgery is not possible.
Radiation therapy may be given in two ways. External radiation comes
from a large machine. Generally, external radiation treatments are given
five days a week for several weeks. The treatment schedule depends on
the type and size of the tumor and your age. Giving the total dose of
radiation over an extended period helps to protect healthy tissue in the
area of the tumor.
External radiation may be directed just to the tumor, the surrounding
tissue or the entire brain. (Sometimes the radiation is also directed to
the spinal cord. When the whole brain is treated, the patient often
receives an extra dose of radiation to the area of the tumor. This boost
can come from external radiation or from an implant.
Radiation also can come from radioactive material placed directly in the
tumor, or implant radiation therapy. Depending on the material used, the
implant may be left in the brain for a short time or permanently.
Implants lose a little radioactivity each day. The patient stays in the
hospital for several days while the radiation is most active.
The Gamma Knife, or stereotactic radiosurgery, is another way to treat
brain tumors. The Gamma Knife isn't actually a knife, but a radiation
therapy technique that delivers a single, finely focused, high dose of
radiation precisely to its target. Treatment is given in just one
session. High-energy rays are aimed at the tumor from many angles. In
this way, a high dose of radiation reaches the tumor without damaging
other brain tissue.
Chemotherapy
Chemotherapy is the use of drugs to kill cancer cells. The doctor may
use just one drug or a combination, usually giving the drugs orally or
by injection into a blood vessel or muscle. Intrathecal chemotherapy
involves injecting the drugs into the cerebrospinal fluid.
Chemotherapy is usually given in cycles. A treatment period is followed
by a recovery period, then another treatment period and so on. Patients
often don't need to stay in the hospital for treatment and most drugs
can be given in the doctor's office or clinic. However, depending on the
drugs used, the way they are given and the patient's general health, a
short hospital stay may be necessary.
Advances in chemotherapy include direct placement into the tumor cavity
using a new technique called convection enhanced delivery.
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