About the brain and brain tumors
The central nervous system (CNS) consists of the brain and spinal cord. The brain is an important organ that controls thought, memory, emotion, touch, motor skills, vision, respirations, temperature, hunger, and every process that regulates our body.
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Cerebrum (supratentorial, or front of brain), composed of the right and left hemispheres. Functions of the cerebrum include: initiation of movement, coordination of movement, temperature, touch, vision, hearing, judgment, reasoning, problem solving, emotions, and learning.
- Brainstem (midline, or middle of brain), includes the midbrain, the pons, and the medulla. Functions of this area include: movement of the eyes and mouth, relaying sensory messages (i.e., hot, pain, loud), hunger, respirations, consciousness, cardiac function, body temperature, involuntary muscle movements, sneezing, coughing, vomiting, and swallowing.
- Cerebellum (infratentorial, or back of brain), located at the back of the head. Its function is to coordinate voluntary muscle movements and to maintain posture, balance, and equilibrium.
How is a brain tumor diagnosed?
In addition to a complete medical history and physical examination of your child, diagnostic procedures for a brain tumor may include:
- Neurological exam. Your child's physician tests reflexes, muscle strength, eye and mouth movement, coordination, and alertness.
- Computed tomography scan (also called a CT or CAT scan), a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.
- Magnetic resonance imaging (MRI), a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body. Spectroscopy is a technique sometimes used to evaluate an area for possible tumor. a functional MRI can assist the doctors in identifying the location of a tumor in relation to important areas such as the speech and motor areas of the brain.
- X-ray, a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
- Bone scan. Pictures or x-rays are taken of the bone after a dye has been injected that is absorbed by bone tissue. These are used to detect tumors and bone abnormalities.
- Angiogram. A dye is used to visualize all the blood vessels in the brain in order to detect certain types of tumors.
- Lumbar puncture/spinal tap. A special needle is placed into the lower back, into the spinal canal. This is the area around the spinal cord. A small amount of cerebral spinal fluid (CSF) can be removed and sent for testing. CSF is the fluid which bathes the brain and spinal cord.
Diagnosis of a brain tumor depends mostly on the types of cells in which the tumor begins and the tumor location.
Benign and malignant tumors
Brain tumors are classified into two categories, benign or malignant. Malignant tumors are usually cancerous, but their seriousness depends upon the tumor's growth rate, whether or not the tumor cells have spread to other parts of the central nervous system, the feasibility of surgical removal, and the tumor's known response to non-surgical treatment, such as radiation and chemotherapy. Certain malignant tumors respond to radiation or chemotherapy, which may completely destroy tumor cells.
Benign tumors are slow growing and rarely spread. Although noncancerous, they are not always easy to treat. Sometimes they cannot be removed surgically, do not respond to radiation or chemotherapy and continue to grow in the child's brain. Thus, even benign tumors sometimes can behave as if they were malignant. Thanks to advances in medical and surgical technology and increased biological knowledge, tumors previously considered malignant may now be considered more benign.
Management of brain tumors differs according to the patient's age, the tumor location and the kinds of cells that make up the tumor.
Despite extensive research, the cause of brain tumors remains unclear. Sometimes brain tumors are reported within family groups, but these occurrences are extremely rare.
Types of tumors
Brain stem tumors
- 10– 20% of tumors
- The most vicious and malignant tumors in childhood
- 80% of these tumors are malignant astrocytomas (glioblastoma) and grow rapidly, particularly those occurring in the part of the brain known as the pons
Symptoms
- One eye turning inward, facial droop, difficulty to swallow
- Weakness of extremities
- Ataxia (poor muscular coodination)
- One-third of patients have hydrocephalus
Unfortunately, a great majority of tumors in the pons (mid-portion of the brain stem) are not surgically resectable. Total resection may be attempted in those occurring in other parts of the brain stem.
Treatment
- Radiation and chemotherapy together for pontine tumor, but prognosis is extremely poor (two-year survival: 8%)
- Mid-brain or medulla oblongata tumors may be resected without further therapy
Cerebellar astrocytomas
- One of the most benign and favorable tumors among pediatric brain tumors
- Hydrocephalus in 90%
Possible symptoms
- Morning headaches
- Nausea
- Progressive unsteadiness of gait, (if patient has hydrocephalus)
- Head tilt and pain in the back of the head (if patient does not have hydrocephalus)
Treatment
- Surgical resection. Once tumor is completely removed, approximately 95% of patients are cured without further treatment
Cerebral PNET / glioblastoma
- One of the most primitive and malignant tumors among CNS tumors in pediatrics
- Tumors tend to be large and have many blood vessels
Symptoms
- Morning headaches
- Nausea
- Progressive unsteadiness of gait
- Seizures
- Visual disturbances
Treatment
- Attempt resection, then radiation and chemotherapy—even if total resection
- Radiation may be required to the spine because of the tumor's tendency to spread
Choroid plexus papilloma
- Usually benign
- 4% of brain tumors
- Formed within the ventricle
- two-thirds of patients are under two years of age
Symptoms
- Headaches and emesis
- Lethargy (related to hydrocephalus)
Treatment
- Surgical resection
- Seizures or hydrocephalus may be a problem post-operatively
Craniopharyngioma
- 5–13 % of tumors
- Arises in embryonically misplaced cells in the base of the brain
- A large number are surgically resectable, however, endocrine function is often disturbed post-operatively
The most common endocrine problems are lack of growth hormone production, adrenocordicoidal hormone, sex and thyroid hormone, and diabetes insipidus (too much urine output and extreme thirst).
Symptoms
- Visual disturbance
- Possible hydrocephalus
Treatment
- Surgical resection
- Possible radiation to any residual tumor
- Frequent endocrine abnormalities following radical tumor resection, needing hormone replacement therapy
Ependymomas
- 10% of brain tumors
- May invade the brainstem
- Histologically benign, but behaves malignant
- Recurrence rates are much higher than even medulloblastomas
- Hydrocephalus in 85%
Symptoms
- Morning headaches
- Nausea
- Progressive unsteadiness of gait
Treatment
- Surgical resection followed by radiation if only a partial resection was possible
- If totally resected, no further therapy with close surveillance MRIs
- Extent of surgical resection is the major factor for outcome
- Recurrent tumor is difficult to treat: treatment is resection followed by chemotherapy
- Currently, the five-year survival rate is as low as 40% for posterior fossa ependymoma tumors
Hypothalamic Tumors
- Most are benign astrocytomas and are slow growing.
Symptoms
- Endocrine problems such as precocious puberty and diencephalon syndrome (loss of weight, poor subcutaneous fat development despite good appetite and increasing height).
Treatment
- Surgical removal of part of the tumor is possible but not a total resection. First choice is chemotherapy, then radiation if no response to chemotherapy.
Medulloblastomas
- 15–20% of tumors
- Often presents in the cerebellum and fourth ventricle—resulting in hydrocephalus
- Is malignant and grows rapidly
- Tends to spread through CSF circulation
Although malignant, this is a pediatric brain tumor in which marked improvement of survival and quality of life have been observed. Decades ago the five year survival rate was approximately 20%. The five-year survival rate now is 70–80%.
Survival is influenced by multiple factors. Other than medical and biological factors, the institution (a university-affiliated hospital like Children's Memorial Hospital vs. a community hospital) may make a large difference in patient's prognosis.
Symptoms
- Morning headaches
- Nausea
- Progressive unsteadiness of gait
Treatment
- Surgical removal followed by radiation and chemotherapy.
Optic chiasm and hypothalamic gliomas
- A majority of these tumors are benign astrocytomas and are slow growing 30% of optic gliomas are associated with neurofibromatosis
- More aggressive if they occur during the first two years of life
Symptoms
- Visual acuity changes
- Nystagmus (involuntary rapid and rhythmic movement of the eyeball)
- Failure to thrive
- Hydrocephalus
Treatment
- Because they are unresectable, the first choice of treatment is chemotherapy. Radiation is used if tumor progresses. Surgical resection is rarely recommended.
Pineal Region Tumor
- Malignant in 80% of cases
- 3–8% of tumors
- Almost invariably present with hydrocephalus
- Tumors may secrete specific tumor markers, named Beta HCG Alpha fetoprotein
Treatment
- Some tumors may be resected, but it is difficult
- Surgery/radiation/chemotherapy are needed for most malignant pineal tumors
- Malignant germ cell tumors respond to chemotherapy so that treatments usually start with chemotherapy
Thalamic Tumor
- Most are benign astrocytomas, though some are malignant
- 80% of patients have hydrocephalus
- May be resectable, but motor weakness and speech difficulty may occur
Symptoms
- Hand tremors
- Weakness of extremities
- Headaches and nausea (related to hydrocephalus)
Treatment
- Surgical resection for benign tumor
- Radiation if unresectable
- Radiation and chemotherapy if tumor is malignant