Pediatrics
Pediatric Brain Tumor Q & A
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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.
- 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
Other common primary brain tumors not derived from glial tissue include:
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 visio
- 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.
Reprinted with permission. © 2004 Blethen Maine Newspapers Inc.