What is a Brain Tumor?
What Causes Brain Tumors?
What
are the Different Types of Brain Tumors?
Why Do Children
Get Brain Tumors?
What are
the Symptoms of a Brain Tumor?
How Do You Diagnose
a Brain Tumor?
What
Type of Specialist Physicians are Involved With the Diagnosis and
Treatment
of Pediatric Brain Tumors?
What
are the Options for Treatment for Pediatric Brain Tumors?
What
Does a Craniotomy and Resection of a Brain Tumor Entail?
What Kind of
Follow-Up Care is Needed?
What
Type of Support is Available for the Family?
What
is a Brain Tumor?
The brain is a spongy mass of nerve cells and tissue,
which comprises three major parts: cerebrum,
cerebellum,
and brain stem. The cerebrum is the
largest part of the brain and controls sensation, speech, emotions, reading,
thinking, and learning. The cerebellum controls balance, walking, and talking.
The brain stem connects the brain with the spinal cord and controls basic
bodily functions, such as breathing, blood pressure, and body temperature.
The bony plates of the skull and fibrous tissue called
dura
protect the brain. The brain is cushioned by cerebral
spinal fluid (CSF) produced by ventricles,
which are fluid-filled spaces in the brain.
Tumors are cells that
divide too often and without any order. Brain tumors can be benign or malignant.
Benign brain tumors are localized, have clear borders,
and do not invade other tissues. However, benign brain tumors can cause
damage because as they grow, they can put pressure on sensitive areas of
the brain, resulting in changes in vision, movement, and other symptoms.
If a benign brain tumor can be completely removed, it will usually not
recur.
Malignant brain tumors grow rapidly and invade surrounding
tissues. These tumors can interfere with vital life functions and are a
threat to life.
What
Causes Brain Tumors?
No one knows what causes brain tumors, although research
is ongoing in this area. Inherited and genetic factors may play a role.
Environmental factors and viruses may also be involved. Certain risk factors
may increase the chance for developing a brain tumor. Workers in oil refining,
rubber manufacturing, drug manufacturing, and chemists and embalmers all
have a higher incidence than average in developing brain tumors. However,
at the present time, there is no clearly defined risk factor.
What
are the Different Types of Brain Tumors?
Brain tumors are named for both the type of cells they
contain and their location in the brain. Primary
brain tumors are tumors that originate in the brain. Secondary
brain tumors are cancers that have spread to the brain from
another part of the body. About 40 percent of all primary brain tumors
are benign.
The most common kind of primary brain tumors in children
derive from
glial (supportive) tissue.
These include:
-
Astrocytomas: Arise from
astrocytes
(star-shaped cells) and grow in both brain and spinal cord. In children,
astrocytomas commonly grow in the brain stem, cerebrum, and cerebellum.
Pilocytic
astrocytoma (a common type of astrocytoma) is slow growing and
often cured by surgery alone.
-
Brain Stem Gliomas: Arise
from the brain stem portion of the brain that controls vital functions.
This tumor cannot generally be surgically removed because of its location
in this vital area. Malignant glioma is one of the more common types of
primary brain tumors.
-
Ependymomas: Arise from
the lining of the ventricles and spinal cord. They are common in children
and adolescents.
-
Oligodendrogliomas: Arise
from myelin-producing cells (fatty covering that protects nerve cells)
in the cerebrum. They are slow growing and rarely occur in children.
Other common primary brain tumors not derived from glial
tissue include:
-
Medulloblastomas: Arise
from a primitive type of developing nerve tissue in the cerebellum part
of the brain. They commonly occur in children (15 to 20 percent of all
pediatric brain tumors), especially males, and can spread to other parts
of the body through the spinal fluid.
-
Meningiomas: Arise from
the meninges, which are membranes that
cover the brain, and are usually benign. They are slow growing and are
most common in women, ages 30 to 50.
-
Schwannomas: Arise from
the covering that surrounds the acoustic nerve,
the nerve that allows us to hear, and they are benign. Acoustic neuromas
affect mostly women and occur in adults.
-
Craniopharyngiomas: Arise
from the pituitary gland near the hypothalamus and are usually benign.
But because of their location and their ability to impact on vital functions,
they are considered malignant. They occur in children and adolescents.
The most common pediatric brain tumors are astrocytoma (nonspecific),
pilocytic astrocytoma, malignant glioma, and medulloblastoma.
Why
Do Children Get Brain Tumors?
Tumors of the central nervous system (CNS) are most common
in two age groups: children ages 3 to 12 and adults ages 40 to 70. According
to the Central Brain Tumor Registry US, (1990-1994),
approximately nine percent (1,831) of the total number of primary brain
tumors occurred in children younger than 20. A total of 3,000 cases of
benign and malignant tumors are found in children every year. These tumors
are slightly more common in boys than girls.
What
are the Symptoms of a Brain Tumor?
The symptoms from a brain tumor depend on tumor size and
the location. Symptoms are usually nonspecific and they get worse over
time. Early detection of brain tumors in children is often difficult because
the symptoms are similar to those of common childhood illnesses. Common
symptoms of pediatric brain tumors include:
-
Headaches: Headaches are common in all children. Less than
one-tenth of one percent may indicate that a brain tumor is present. However,
any headache that is not relieved by Tylenol and/or is associated with
vomiting or vision changes needs to be followed up by a specialist.
-
Seizures
-
Nausea and vomiting
-
Weakness or loss of sensation in the limbs
-
Difficulty walking
-
Changes in vision
-
Sleepiness
-
Changes in personality or memory
-
Changes in speech
How
Do You Diagnose a Brain Tumor?
A complete history and physical examination is the first
step taken. The child’s pediatrician will need to make the appropriate
referral to a neurologist, who after a complete neurological exam, may
order special diagnostic tests. These diagnostic tests may include special
imaging scans, such as a computerized tomography
(CT) scan, magnetic resonance imaging (MRI)
scan, and positron emission tomography
(PET) scan. These imaging studies depict the tumor and its location in
the brain. MRI especially identifies the tumor and proximity to vital structures.
In addition, a lumbar puncture or spinal tap may be needed to detect abnormal
cells in the spinal cord. Angiogram or arteriogram allows physicians to
see the blood vessels in the brain and whether they are involved in the
brain tumor. An electroencephalogram (EEG) measures the electrical activity
in the brain.
What
Type of Specialist Physicians are Involved With the Diagnosis and Treatment
of Pediatric Brain Tumors?
A pediatrician will usually be the first physician to
examine the child with a possible brain tumor. A pediatric neurologist
and/or pediatric neuro-oncologist will then be consulted, as well as a
radiologist to help with all the special tests needed to pinpoint a particular
brain tumor.
If the brain tumor can be removed by surgery, then a pediatric
neurosurgeon will be consulted. An anesthesiologist specializing in pediatric
neuroanesthesia will take care of the child during the surgery. A nurse
practitioner and nurse clinician will coordinate all the different facets
of the child’s care, both preoperatively and postoperatively into recovery.
Physicians specializing in rehabilitation will help the child regain strength
and return to normal daily activities. A radiation oncologist,
dietician, social worker, physical therapist, and speech
therapist often round out the team of medical specialists.
What
are the Options for Treatment for Pediatric Brain Tumors?
Surgery is the primary treatment for many brain and spinal
cord tumors. Surgery is indicated if the brain tumor can be completely
removed. It may also be indicated if only a portion of the brain tumor
can be safely removed in order to relieve symptoms and decrease the amount
of tumor needed to be treated by chemotherapy or radiation. Image-guided
surgery technology allows the neurosurgeon to see the brain in three dimensions
and pinpoint the tumor with the aid of CT and MRI. Using this new technology,
neurosurgeons are able to open the skull (craniotomy)
using very small incisions. General anesthesia is needed to render the
patient unconscious not only to shield the patient from pain, but to provide
comfort and a quiet operating field for the neurosurgeons. Depending on
the site of the surgery, there may be complications such as bleeding requiring
transfusion, loss of certain physical and mental functions, seizures, postoperative
weakness, nausea and vomiting, muscle aches and pains, and sore throat.
Pain is generally mild after the surgery although a headache is very common.
Neurosurgeons have available many special tools to help
them perform the surgery. High-powered microscopes help the surgeons see
the tumor. Three-dimensional mapping techniques and image-guided surgery
help the surgeons accurately locate the tumor so that the incision can
be as small as possible. Three-dimensional tracking also helps the surgeons
make sure that the entire tumor was removed. Lasers and ultrasonic aspirators
help to vaporize and break up the tumor. Fibrin glue helps to prevent bleeding
and CSF leakage through the incision.
Chemotherapy
If tumors cannot be completely removed with surgery,
then chemotherapy and radiation can be used. Chemotherapy uses toxic drugs
given either internally (injecting into blood vessel) or intrathecally
(injecting into CSF) to kill tumor cells. It is given over a period of
time either in the hospital, outpatient clinic, or even at the doctor’s
office or home setting.
Chemotherapy drugs all have some side effects, such as
nausea and vomiting, hair loss, weakness, indigestion, and gum soreness.
These side effects can be treated and alleviated by many different medications.
Radiation therapy
Radiation therapy or radiotherapy is used when surgery
is not possible, as an adjunct to surgery to shrink tumor cells before
surgery, or to kill any remaining tumor cells after surgery. Radiation
therapy uses high-energy x-rays specifically targeted on the tumor cells.
It can be given either externally from a machine or internally from radioactive
pellets surgically placed directly into the tumor (implant radiation therapy).
Radiation therapy has side effects, including nausea and vomiting, weakness,
skin reactions at the treated site (redness and itchiness) and loss of
appetite. All of these side effects can be treated and alleviated by many
different medications.
Other medications
-
Steroids are often given to reduce swelling (brain edema)
from the brain tumor
-
Anticonvulsants are frequently given to prevent or control
seizures. The brain tumor can irritate surrounding brain tissue and cause
seizures
Other procedures
-
Ventriculoperitoneal (VP) shunts can alleviate hydrocephalus.
Hydrocephalus occurs if the normal flow of cerebral spinal fluid through
the ventricles of the brain is blocked by the tumor, leading to increased
pressure in the brain. Brain tumors can block the normal flow of CSF and
cause pressure buildup and pain.
-
Even if the brain tumor cannot be removed by surgery, a biopsy
of the brain tumor may be performed in order to obtain an accurate diagnosis
of the tumor and to direct the type of treatment.
What
Does a Craniotomy and Resection of a Brain Tumor Entail?
A craniotomy is an opening created in the bone to expose
the brain and the tumor. The dura is then opened, and using a microscope
and special microinstruments, the tumor is removed without injuring any
normal brain tissue.
What
Kind of Follow-Up Care is Needed?
The follow-up requires the patient to see the neurosurgeon
and neurologist on a routine basis. If the tumor is benign, the child will
just need several MRIs at specific intervals for surveillance. If the tumor
is malignant, the child will then need adjuvant chemotherapy, radiation
therapy, or combination of the two.
What
Type of Support is Available for the Family?
There are many support groups available locally or nationally
for children with brain tumors. These groups provide literature as well
as discussion with other families and children who have undergone similar
procedures.
