MGHbanner BulfinchBldg
MGH  Neurosurgical Service Home
MGH Neurosurgical Service
Massachusetts General HospitalHarvard Medical School
MGH Shield Hvd Med Sch Shield Partners Logo
Neurosurgery @ MGHPeople @ MGH NeurosurgeryClinical Centers @ MGH NeurosurgeryResearch @ MGH NSEducation @ MGH NeurosurgerySupport Groups @ MGH NeurosurgeryNews @ MGH NeurosurgeryReferrals @ MGH Neurosurgery

Copyright ABTA, 1991

Fifth Edition


A Patient's Reference Manual the hope that through knowledge comes comfort and strength...

American Brain Tumor Association
2720 River Road
Des Plaines, Illinois  60018-4110
(847) 827-9910

We suggest you use this booklet as a reference. Read those topics which apply to your situation at the present time. In the future, you may find it helpful to read other sections.


Return to the ABTA homepage

Return to the MGH Neurooncology homepage for more on-line brain tumor resources

SECTION 1 What is a brain tumor?


Brain tumors are tumors that grow in the brain. A tumor is an abnormal growth caused by cells reproducing themselves in an uncontrolled manner.

When doctors describe tumors in parts of the body other than the brain, they use the words benign (meaning harmless) or malignant (meaning cancerous). These meanings change, however, when referring to tumors in the brain.

Benign brain tumors:

A benign brain tumor consists of benign (harmless) cells and has distinct boundaries. Surgery alone may cure this type of tumor.

Malignant brain tumors:

A malignant brain tumor is life-threatening. It may be malignant because it consists of cancer cells, or it may be called malignant because of its location. In other words, a brain tumor composed of benign cells--but located in a vital area--is still considered malignant.

A malignant brain tumor made up of cancerous cells may spread or seed (metastasize) to other locations in the brain or spinal cord. It can invade and destroy healthy tissue so it cannot function properly. Malignant tumors grow the way a plant does, with "roots" invading various tissues. Or, they can shed cells that travel to distant parts of the brain. Some cancerous tumors, however, remain localized.

Malignant brain tumors seldom metastasize outside the brain and spinal cord. [Central Nervous System (CNS)]

The bones of the skull hide brain tumors. The doctor can not feel or see them during a routine examination. Scans produce pictures that suggest a particular type of tumor. Only a sample of tumor examined under a microscope can provide an exact diagnosis . If this type of examination is not possible, an educated assumption is made based on available test results.

Often, the damage done by brain tumors is due to their size. Because the skull is bone, it cannot expand to make room for even a small mass growing within it. As a result, the tumor presses on and displaces normal brain tissue. This pressure may damage or destroy delicate brain tissue. Many of the symptoms of a brain tumor are caused by this pressure. Sometimes, a tumor may cause blockage of fluid that flows around and through the brain. This blockage can also create increased pressure. Some brain tumors also cause swelling due to accumulation of fluid (edema). Size, pressure, and swelling all create this "mass effect."


Tumors that start in the brain are primary brain tumors.

Metastatic brain tumors are tumors formed by cancer cells that start elsewhere in the body and spread to the brain.

Naming Tumors

Tumor names depend on where the tumor originated, its pattern of growth, and whether it is cancerous or not. The following are some general names of tumors:

ADENOMA A usually benign tumor arising from a gland; for example, pituitary adenoma.

BLASTOMA A malignant tumor whose cells have undeveloped(embryonic) characteristics; for example, medulloblastoma or glioblastoma multiforme.

CARCINOMA A malignant tumor that arises from skin or the lining of the digestive, respiratory, and urogenital systems; for example, lung cancer (small cell carcinoma) or colon cancer (adenocarcinoma).

SARCOMA A malignant tumor that arises from connective tissue, blood vessels, or the lymph system; for example, osteosarcoma.

GLIOMA The general name for a tumor that arises from the supportive tissue of the brain; for example, astrocytoma or oligodendroglioma. It may be benign or malignant.

Some tumors may undergo further change (mutation). A benign growth may become malignant. In some tumors, a lower-grade tumor may recur as a higher-grade tumor.

Grading Tumors

Tumor grade indicates the degree of malignancy. Grade is based on the tumor's tendency to spread (infiltrate), its growth rate, and its similarity to normal cells.

Tumors with distinct borders (circumscribed), considered grade I, are sometimes referred to as benign or mildly malignant. Those tumors either do not grow or grow slowly.

Infiltrating tumors are those that tend to grow into surrounding tissue. Of the infiltrating tumors, the terms low-grade, mid-grade, and high-grade are frequently used. However, the exact system used to grade tumors varies with each specific family of tumors.

Tumors often contain several grades of cells. The highest or most malignant grade of cell found during microscopic examination determines the grade, even if most of the tumor is a lower grade.

Tumor diagnosis by name and by grade is very important for both treatment and prognosis.

SECTION 2 What are the parts of the brain and what does each part do?

The brain--a soft, spongy mass of nerve and supportive tissue--sits inside the skull. The base of the brain is connected to the spinal cord. The brain, the spinal cord, and the nerves that extend out from the brain and spinal cord into various parts of the body, act together to send information to the brain and relay instructions from the brain.

This chapter discusses the various parts of the brain. You can jump to a discussion of a particular part by clicking on the links (usually-blue or purple depending on your web-browser)

Words in this section that appear in BOLD FACE PRINT refer to brain structures or areas.

The brain is made up of four main structures, plus a number of other specialized areas. To begin with, the brain is covered by three membranes.


The meninges are three, thin layers of tissue (membranes) that completely cover the brain and the spinal cord. The three layers of meninges are the dura mater, the arachnoid, and the pia mater. Spinal fluid flows in the space between the arachnoid and the pia mater membranes. This is the called the subarachnoid space.

The tentorium is a flap of the dura mater that separates the cerebral hemispheres from the other major structures of the brain. Supratentorial refers to the area above the tentorium. Infratentorial refers to the area below the tentorium. (see figure 1)



1. The largest area of the brain is the Cerebrum. It consists of two hemispheres or halves, the right and left cerebral hemispheres. The right cerebral hemisphere controls the left side of the body. The left cerebral hemisphere controls the right side of the body.

The outer layer of the cerebrum--called the cerebral cortex--is made up of gray matter. The inner portion of the cerebrum is white matter. In addition, there are areas of gray matter, called basal ganglia, deep within the brain.

Gray matter is composed of nerve cells. These cells control brain activity. White matter is composed of myelinated nerve cell axons that carry information between nerve cells in the brain and spinal cord. Oligodendrocytes and astrocytes are support cells that help maintain the myelin covering of nerve axons and nerve cell bodies, respectively.

Deep indentations called fissures divide each half(hemisphere) of the cerebrum into four lobes (sections): Frontal Lobe, Parietal Lobe, Temporal Lobe, and Occipital Lobe. Each lobe controls a specific group of activities. (see figure 2)

Frontal Lobe: The frontal lobe of each hemisphere controls voluntary muscle movements on the opposite side of the body. The frontal lobe of the dominant hemisphere controls speech and writing. (The dominant hemisphere is the left hemisphere in all right-handed and some left-handed individuals, and the right hemisphere in most left-handed people.) Other frontal lobe activities include intellectual functioning, thought processes, behavior, and memory.

Parietal Lobe: The parietal lobe receives and interprets sensations. These sensations include pain, temperature, touch, pressure, size, shape, and body-part awareness. Other activities of the parietal lobe are hearing, reasoning, and memory.

Temporal Lobe: The temporal lobe is involved in the understanding of sounds and spoken words, as well as emotion and memory.

Occipital Lobe: The occipital lobe is involved in the understanding of visual images and the meaning of written words.


2. The Cerebellum is the second largest area of the brain. It consists of two hemispheres or halves connected by the vermis . The cerebellum connects to the brain stem. (see figure 3)

The cerebellum, together with the thalamus and cerebrum , controls skilled muscular coordination, including walking (gait) and speech (articulation).


3. The Pons coordinates the activities of the cerebrum and cerebellum by relaying impulses between them and the spinal cord. The pons contains the origins of the 5th, 6th, 7th, and 8th cranial nerves. (see figure 5)

Medulla Oblongata

4. The Medulla Oblongata controls breathing (respiration), heart beat, and vomiting. It connects the brain with the spinal cord. It contains the origins of the 9th, 10th, 11th, and 12th cranial nerves. (see figure 5)

Besides these four main structures, many other specialized nerve structures are part of the brain.


There are four connected cavities or ventricles in the brain. Inside each ventricle are structures called choroid plexus. The choroid plexus forms spinal fluid, which flows through the ventricles and the subarachnoid space surrounding the brain and spinal cord. (see figure 4)

There are two lateral ventricles, one in each cerebral hemisphere. The third ventricle is beneath the corpus callosum and surrounded by the thalamus. The fourth ventricle is between the hemispheres of the cerebellum. It is an expansion of the central canal of the medulla oblongata.

The cerebral aqueduct, called the aqueduct of Sylvius , is a narrow canal connecting the 3rd and 4th ventricles.


The hypothalamus makes up part of the wall of the thirdventricle and is the base of the optic chiasm. It controls water balance, sleep, temperature, appetite, and blood pressure. The hypothalamus coordinates patterns of activity and controls emotions. It is also the control center for the pituitary gland. (see figure 5)


The thalamus surrounds the third ventricle. It monitors input from the senses and acts as a relay station for the sensory center of the cerebrum. (see figure 5)


The limbic system, together with the hypothalamus, controls hunger, thirst, emotional reactions, and biological rhythms. In addition, it coordinates complex activities requiring a sequence of performance steps. (see figure 5)


There are 12 pairs of cranial nerves: (see figure 6)

NUMBER          NAME                    FUNCTION
   1            Olfactory               Smell
   2            Optic                   Vision
   3            Oculomotor              Eye movement
   4            Trochlear               Eye movement
   5            Trigeminal              Facial sensation
   6            Abducent                Eye movement
   7            Facial                  Face movement
   8            Vestibulocochlear       Hearing and balance
   9            Glossopharyngeal        Taste and gag reflex
  10            Vagus                   Involuntary muscles     (heart, stomach,                                        
intestines,     throat, chest)
  11            Accessory               Voluntary muscles of the neck
  12            Hypoglossal             Tongue movement


The brain stem controls basic functions, including blood pressure, heart beat, and breathing (respiration). It is the bottom-most portion of the brain, connecting the cerebral hemisphereswith the spinal cord. Several structures are part of the brain stem: (see figure 5)

Pons Reticular Formation

Medulla Oblongata Midbrain


The reticular formation is the central core of the brain stem . It controls consciousness, eating and sleeping patterns, drowsiness and attention. The reticular formation connects with all parts of the brain and brain stem. (see figure 5)


The midbrain is the short portion of the brain stem between the pons and the cerebral hemispheres. The midbrain is a relay center for sight and hearing. (see figure 5)

POSTERIOR FOSSA (also called the Infratentorium)

This is the area within the skull that houses the cerebellum and the brain stem. The tentorium separates it from the cerebral hemispheres. (see figure 1)


The supratentorium is the area above the tentorium (Tentorium: a flap of membrane, part of the meninges). It contains the cerebral hemispheres and other brain structures. (see figure 1)


The pineal body lies below the corpus callosum. It produces the hormone melatonin. This function of this hormone is not known. (see figure 4)

SELLAR REGION (also Suprasellar, Parasellar)

The sellar region is the area around the sella turcica. The sella turcica is the hollow of skull bone that contains the pituitary gland. (see figure 5)


The pituitary gland is attached to and receives messages from the hypothalamus. The pituitary gland is composed of two lobes, the anterior and the posterior. This gland secretes several important hormones. (see figure 5)

Medical terminology used to describe anatomy and location:

anterior/posterior front, forward/back, behind

fossa a depression or hollow of bone

hyper/hypo high, over/low, under

para beside, next to, beyond

sella a small, saddle-shaped depression of bone

sub under, near

supra/infra above, over/below, under

SECTION 3 Who gets brain tumors?

Primary brain tumors occur in people of all ages. Metastatic brain tumors are much more common in adults.

  • Primary malignant brain tumors are the second most common cause of cancer death in children up to 15 years old.
  • They are the second most common cause of cancer death in people ages 15 to 34.
  • They are the third most common cause of cancer death in males ages 35 to 54.

In 1990, primary malignant brain tumors represented about 1.5% of all cancers diagnosed and 2% of the cancer deaths.


The cause of primary brain tumors is unknown. Environmental agents, familial tendencies, viral causes, and other possibilities are under investigation.

Brain tumors are not contagious.


Accurate statistics for the frequency and outcome of brain tumors are not available. It is estimated that in the United States in 1990, there were 20,500 new cases of primary brain tumor . New cases of metastatic brain tumor diagnosed in 1990 were estimated to be at least 20,700. The combined estimate of 41,200 new cases of brain tumor included both benign and malignant brain tumors.

These statistics are based on the 1989 United States population of 249,000,000 people, and an incidence rate of 8.2 per 100,000 for primary brain tumors, and an incidence rate of 8.3 per 100,000 for metastatic brain tumors.

The various types of brain tumors occur with different frequency in children and in adults.

The most common childhood tumors are:

1. Astrocytoma

2. Medulloblastoma

3. Ependymoma

The most common adult tumors are:

1. Metastatic brain tumors from lung, breast, melanoma, and other cancers

2. Glioblastoma Multiforme

3. Anaplastic (Malignant) Astrocytoma

4. Meningioma

SECTION 4 What are the symptoms of brain tumors?


Brain tumors are often difficult to diagnose because their symptoms, which serve as clues for the medical specialist, can be hard to pin down.

In general, the symptoms depend on the size of the tumor and the part of the brain affected. But as a tumor grows, it can affect other parts of the brain, producing new symptoms. The tumor may grow into other areas of the brain, or the "mass effect" may cause the additional symptoms. (See Section 1)

Additionally, the symptoms produced by a brain tumor often mimic the symptoms of other diseases--and vice versa.

Because symptoms may appear gradually, and because they are often not clear-cut, it may be a long time between the beginning of symptoms and the actual diagnosis.


Some patients with brain tumors develop increased intracranial pressure. IICP occurs for several reasons:

  • An increase in the mass within the rigid bones of the skull because of tumor growth
  • Blockage of the flow of cerebrospinal fluid (CSF)
  • Swelling of the tissue around the tumor due to the accumulation of fluid (edema)

When a tumor blocks the normal flow of CSF within the brain, hydrocephalus occurs. Hydrocephalus causes increased pressure within the skull, and the increased pressure damages the delicate structures of the brain.

Symptoms of IICP are:

  • Headache usually just after waking and lessening as the day goes on
  • Vomiting usually just after waking, with or without nausea
  • Mental changes, often sluggishness or drowsiness
  • Uncoordinated, clumsy movements
  • Seizures


Symptoms are what the patient reports to the doctor: sensations, feelings, descriptions.

Signs are what the doctor can observe, either directly or as the result of various tests.

For simplicity, we use the term symptom to mean both signs and symptoms.

Brain Stem Tumors (Midbrain, Pons, Medulla Oblongata)

Tumors of the brain stem can produce a variety of symptoms. The most common symptoms are vomiting, usually just after awakening, and a clumsy, uncoordinated walk (ataxic gait). Muscle weakness on one side of the face causes a one-sided smile or drooping eyelid. Difficulty in swallowing (dysphagia) and difficulty with speech (dysarthria) are also common symptoms. In addition, abnormalities in the functioning of the eye nerves produce "crossed eyes" or decreased vision. Headache, usually just after awakening, may also occur. Head tilt, drowsiness, hearing loss, one-sided muscle weakness (hemiparesis), and personality changes may be present. Symptoms may develop gradually.

Cerebellopontine Angle Tumors (Usually Acoustic Nerve Tumors)

The earliest symptom is ringing or buzzing in the ear (tinnitus). Less often, dizziness (vertigo) may occur. As the tumor grows, additional symptoms such as deafness, and others similar to those of a brain stem tumor may occur. (see figure 3)

Cerebral Hemisphere Tumors

Frontal Lobe Tumors

Common symptoms include one-sided paralysis (hemoplegia), seizures, defective memory, impaired judgment, and personality or mental changes. If the tumor is at the base of the frontal lobe, loss of sense of smell (anosmia), impaired vision, and a swollen optic nerve (papilledema) may occur.

Mental or personality changes and a clumsy, uncoordinated walk (ataxic gait) are common symptoms if the tumor involves both the left and right frontal lobes. (see figure 2)

Parietal Lobe Tumors

Seizures, speech disturbances if the tumor is in the dominant (usually left) hemisphere, and loss of ability to write(agraphia) are common symptoms. Spatial disorders, such as difficulty with body orientation in space or recognition of body parts, may also occur. (see figure 2)

Occipital Lobe Tumors

Blindness in one direction (hemianopsia) and seizures are common symptoms. (see figure 2)

Temporal Lobe Tumors

These tumors usually are "silent." They often cause no symptoms other than occasional seizures or language disorders (dysphasia). (see figure 2)

Subcortical Tumors

One-sided paralysis (hemiplegia) is the most common symptom. These tumors may invade other lobes of the cerebral hemispheres and produce symptoms common to tumors in those locations.

If the tumor invades the thalamus, the sense of touch may be impaired.

Meningeal Brain Tumors

These tumors cause symptoms usually because of pressure and compression rather than by growth into brain tissue. Symptoms depend on the location of the tumor. (See the description of symptoms by location.)

Metastatic Brain Tumors

Symptoms depend on the location of the tumor or tumors in the brain. Headache, nausea, and vomiting are common, because of the swelling (edema) that frequently accompanies these tumors. For specific symptoms, see the description of symptoms by location.

Midline Tumors (Craniopharyngioma, Optic Nerve Glioma, Tumors of the Thalamus and Sellar areas)

Headaches, nausea and a swollen optic nerve (papilledema) are the most common symptoms of these tumors. These symptoms are due to an increase in intracranial pressure. Other symptoms are abnormal eye movement (nystagmus) and vision, and alteration of personality or consciousness. In addition, impairment of glandular functions may cause either delayed or accelerated growth. The development of a water balance problem (diabetes insipidus) is possible.

Posterior Fossa Tumors (Tumors of the Fourth Ventricle, Cerebellar Tumors)

Headaches, nausea, and a swollen optic nerve (papilledema) due to increased intracranial pressure are the most common symptoms. A clumsy, uncoordinated walk (ataxic gait), swaying, and staggering may occur. Tremors, as well as difficulty with other types of coordination and speech are also frequent symptoms. Nerve irritation may cause pain in the back of the head.

Spinal Cord Tumors

Symptoms of these tumors depend on the nerves involved. (see figure 8) Tumors of the thoracic area may cause a "girdle pain" in the chest that worsens with coughing or sneezing. This pain is often worse when the person is lying down. Tumors in the cervical or lumbar areas may cause neck, arm, back, or leg pain. Weakness, muscle wasting or spasms, and sensory changes are other common symptoms. Decrease or lack of bowel or bladder control may occur, depending on the location of the tumor.

SECTION 5 How are brain tumors diagnosed?


The diagnosis of a brain tumor begins in the doctor's office. The doctor begins by asking the patient a number of questions to get a complete history of the symptoms. Then he or she will do a basic neurological examination.


A basic neurological examination includes the following:

  • Eye movement, pupil reaction, and eye reflex tests
  • Hearing tests using a ticking watch or tuning fork
  • Reflex tests using a rubber hammer
  • Balance and coordination tests. Heel-to-toe walking. Heel-to-shin movements. Balance with feet together and eyes closed. Rapid alternating movements such as touching the finger to the nose with eyes closed.
  • Sense of touch tests using a pin point and cotton ball
  • Sense of smell tests using various odors
  • Facial muscle tests--smiling, grimacing
  • Tongue movement, gag reflex tests
  • Head movement tests
  • Mental status tests. Asking for the current time and date. Asking who is President.
  • Abstract thinking test. Asking for the meaning of "a stitch in time saves nine."
  • Memory tests. Asking to have a list of objects repeated. Asking for a description of the food eaten at breakfast yesterday. Asking for a description of the events of last Thanksgiving.

If the results of this examination lead the physician to suspect a brain tumor may be present, additional testing will be scheduled.

Neurological specialists perform several diagnostic tests for brain tumors. These include:


Scans are done in place of conventional x-rays, which are not able to show tumors behind bone. Different types of imaging devices are used to perform brain scans. The most commonly used devices for both diagnosis and follow-up are the Computerized Axial Tomographer (CT or CAT) and the Magnetic Resonance Imager (MRI). Positron Emission Tomography (PET) is also available, but it tends to be used more for research than for routine diagnosis.


This machine combines an x-ray device and computer. Before the CT scan begins, the person being examined is given an injection of a special dye (contrast) material. This dye helps make any abnormal tissue more evident. Then the patient lies on a table that slides into a doughnut-shaped opening. While the patient lies very still, the CT scanner circles the head, and x-rays penetrate the brain. Absorption of the x-rays varies with the type of tissue penetrated. A ring of detectors measures the amount of rays remaining after their path through the brain.

Thousands of thin cross section readings are fed into the computer which then transforms the data into a picture.


The MRI is a tunnel-shaped piece of equipment. The person being examined lies on a table that slides into the tunnel. Inside the scanner, a magnetic field surrounds the patient's head while radio energy is beamed to the area. No x-rays are used. The magnetic field causes atoms in the brain to change direction. The radio waves cause another change of direction. When the beam stops, the atoms relax and return to their original position. During relaxation, the atoms give off signals in differing amounts and at different intervals of time. Antennas pick up these signals and feed them into a computer which assembles a picture. Because different atoms have their own characteristic radio signals, the computer can distinguish between healthy and diseased tissue. A contrast material (Gadolinium) may be used with the MRI.

Because the MRI ignores bone which can obstruct CT images, this device provides clearer pictures of tumors located near bone. The MRI can also produce a wider variety of image angles. The MRI can detect edema but has difficulty distinguishing edema from tumor.

Some tumors have calcification, which the MRI cannot detect. MRI imaging takes longer than a CT scan, and it is very noisy. Patients with cardiac monitors, pacemakers, or surgical clips cannot take an MRI because of the magnetic fields.


In a PET scan, a low-dose radionuclide produced by a cyclotron (an atom smashing radiation unit) is coupled to a chemical such as glucose (a sugar) and injected into the patient. The PET scanner rotates around the patient's head, detecting the rays emitted by the radioactive sugar. Highly malignant tumors consume glucose at a higher rate than normal brain.

Measurements of brain activity (determined by concentrations of the glucose) feed into a computer, which produces a color-coded moving picture or a gray scale image of the brain as it converts food (glucose) into energy.

The use of PET is limited because cyclotrons are scarce.

The following type of scan may be used with tumors having a large blood supply. (vascular)

RN (Radionuclide)

A radionuclide (RN) scan uses short-lived radioactive material injected into a vein in the arm. The scanner moves back and forth over the patient's head, plotting a chart. The chart shows the various concentrations of the injected material in the brain.

The contrast materials used with CT or MRI scanners concentrate in diseased tissue in larger quantity than in healthy tissue. The radioactive materials used with RN scanners also concentrate in diseased tissue. In all three cases, the concentration is due to the leakiness of blood vessels in and around brain tumors. The concentration of contrast materials or radioactive drug outlines abnormalities such as tumors.

A neuroradiologist interprets the computer images produced by the CT, MRI, PET, and RN scans. The pictures help establish a tentative diagnosis. Scans do not show a specific type of tumor. Only examination of an actual sample of tumor tissue can provide an exact diagnosis.


Lumbar puncture is used to obtain a sample of spinal fluid. The fluid is then examined in a laboratory to determine if tumor cells, infection, protein, or blood is present. Lumbar puncture is also used to inject a dye before a myelogram. A myelogram is a test used primarily for spinal tumors.

Lumbar puncture is never done if there is suspicion of increased intracranial pressure because of the risk of the brain bulging through an opening in a membrane, muscle, or bone. (herniation)

On an experimental basis, tests of spinal fluid may help identify tumor markers (substances which indicate the presence of a tumor). A tumor marker is important. Colon cancer patients, for example, have their blood tested every few months. The doctor looks for an increase in a substance known as CEA. When CEA increases, it is almost certain that the colon cancer has returned or is growing. Thus, CEA serves as an early warning system for treatment to begin. Unfortunately, most brain tumors have no tumor markers. (At this time, pineal region tumors are the only brain tumors that can sometimes be diagnosed using markers.)


An EEG is used to record electrical activity of the brain, particularly of the cerebral hemispheres, using electrodes attached to the scalp.


A biopsy is a surgical procedure used to remove a small amount of tumor tissue. The neurosurgeon then submits samples of the tumor tissue to a neuropathologist for analysis. An accurate diagnosis is then possible.

For those areas not easily reached via an open biopsy, a surgeon can, through a small hole made in the skull, use stereotaxic instrumentation to obtain a "closed" biopsy. Stereotaxic instrumentation allows the surgeon to precisely position a biopsy probe in three-dimensional space to allow access almost anywhere in the brain. In most instances, therefore, it is possible to obtain tissue for diagnosis, if it is desired. When biopsy is not performed, diagnosis relies solely on scan test results and their interpretation.

The following tests are used primarily for pre-operative information rather than for diagnosis:


After injection of a contrast material into a deep artery, x-rays follow the flow of the material through the blood vessels of the brain. This test usually requires prior sedation, as it can be uncomfortable. The angiogram shows the position of the blood vessels near the tumor and the extent of the tumor's blood supply. (vascularity)

MRI angiography will be available at many medical centers in the near future. This will, to a great extent, replace invasive arteriography.


Evoked-potential testing uses small electrodes to measure the electrical activity of nerves. The test can be used to determine areas controlled by an individual nerve. Evoked- potentials may serve as a guide during the surgical removal of tumors growing around important nerves.

SECTION 6 What are the different types of brain tumors?

Classification is the grouping of tumors on the basis of their characteristics. Each tumor is then given a unique name. Several different brain tumor classification systems are now in use. The consistent naming of brain tumors is very important when gathering statistics for incidence, etiology (cause), effectiveness of treatment, and prognosis.

The following is an alphabetical list of the most common brain tumors. Included in the list are alternate names commonly in use.

Acoustic Neuroma (Neurilemmoma, Schwannoma, Neurinoma)

The acoustic neuroma is a benign tumor of the nerve of hearing (the acoustic or 8th cranial nerve). It is located in the angle between the cerebellum and the pons, in the posterior fossa. This tumor grows very slowly.

Acoustic neuromas occur in adults, particularly in their middle years. Females are twice as likely to have this tumor as males. Acoustic neuromas account for about 9% of all brain tumors.

Common symptoms are loss of hearing in one ear and buzzing or ringing in the ear (tinnitus), with dizziness occurring less commonly. If the tumor also affects the adjacent 7th nerve (facial nerve), facial paralysis and loss of facial sensation may occur. Other symptoms may include difficulty in swallowing, impaired eye movement, taste disturbances, and unsteadiness.

Often, total surgical removal is possible.

For additional information about acoustic neuromas, contact the Acoustic Neuroma Association, P. O. Box 398, Carlisle, PA 17013, 717/249-4783.

Adenoma (See Pituitary Adenoma)


Astrocytomas are tumors that arise from astrocyte cells-- part of the supportive tissue of the brain. These cells are named for their star-like shape.

There are different classification systems used to grade astrocytomas. One system grades these tumors on a scale of I to IV. In that system, grade I tumors tend to be benign and grade IV tumors the most malignant (glioblastoma multiforme). Other classification systems, including the World Health Organization, separate astrocytomas into distinct types that more closely reflect outcome. Important types of astrocytomas, in increasing degree of malignancy, are: the benign juvenile pilocytic astrocytoma, astrocytoma, anaplastic astrocytoma, and glioblastoma multiforme. In addition, these tumors may be classified by the nervous system location in which they occur, such as optic nerve glioma or brain stem astrocytoma (or glioma). The astrocytoma can also be mixed with oligodendroglioma and/or ependymoma tumor elements. These tumors are then called mixed gliomas.

Because grading systems vary, we have divided the astrocytomas into three groups: low-grade astrocytomas, mid-grade and high-grade astrocytomas.

Low-Grade Astrocytoma

Low-grade astrocytomas often have well-defined borders. Some low-grade astrocytomas form cysts or are enclosed in a cyst. Metastasis is rare. Although these tumors are usually slow growing, they can invade large areas.

The lowest grade astrocytomas are the juvenile pilocytic astrocytomas , and subependymal giant cell astrocytomas.

Juvenile pilocytic astrocytomas occur mainly in children. They are considered to be the most benign of the astrocytomas. Cerebellar astrocytomas and optic nerve gliomas are often pilocytic tumors.

The subependymal giant cell astrocytoma is the ventricular tumor typically associated with tuberous sclerosis.

Infiltrating low-grade astrocytomas are a bit more malignant. These are called low-grade astrocytoma or astrocytoma. They are often found in the temporal lobe of the cerebral hemispheres.

Location of the tumor often determines treatment. Complete surgical removal is sometimes possible for accessible (accessible tumors can often be surgically removed without causing severe neurological damage) tumors. After total surgical removal, periodic follow-up with MRI or CT scans may be the only additional care required. Radiation therapy is used for incompletely removed or inoperable low-grade astrocytomas, or for those that recur. Chemotherapy for these is uncommon except for recurrences. Intracavitary radiation may be effective for cystic tumors.

Mid- and High-Grade Astrocytoma

These astrocytomas are truly malignant tumors. Included in the mid-grade group are the gemistocytic astrocytoma, anaplastic astrocytoma, and malignant astrocytoma. The high-grade group is represented by the glioblastoma multiforme and a variant, the gliosarcoma.

The mid- and high-grade astrocytomas grow more rapidly than low-grade tumors and tend to invade nearby healthy tissue. These tumors recur more frequently than some lower grade tumors because their tendency to spread into surrounding tissues (invasiveness) makes it difficult to completely remove them during surgery.

Treatment is based on the extent of the spread of the tumor. Surgery followed by radiation therapy is the treatment of choice for accessible high-grade astrocytomas. Inoperable tumors are usually treated with radiation therapy. Chemotherapy is frequently given after surgery and/or radiation therapy; chemotherapy is most effective for the mid-grade astrocytomas. Investigational immunotherapy treatments are also available.

Recurrent tumors

Many malignant tumors cannot be removed completely during surgery because they have spread into surrounding tissues. They therefore tend to recur. Surgery may be used to treat accessible recurrent astrocytomas. Conventional radiation therapy may be given if it was not done as an initial treatment. Focused high-dose focal radiation therapy, such as implantation of radiation directly into the tumor (interstitial radiation) can be used if conventional radiation therapy has already been given. Chemotherapy is also used to treat recurrent tumors. It appears to be more effective for the mid-grade tumors.

For additional information, refer to the ABTA publications About Glioblastoma Multiforme and Malignant Astrocytoma; Radiation Therapy of Brain Tumors: Part I and Part II; Chemotherapy of Brain Tumors; Immunotherapy of Brain Tumors.

Brain Stem Glioma

Brain stem glioma may be a an astrocytoma, anaplastic astrocytoma, glioblastoma multiforme, a mixed tumor. This tumor location is more common in children than in adults.

MRI images are superior to CT images for detecting these tumors.

Brain stem gliomas are not always solely in the center of the brain stem. They may have external branches as well. Because of their location, most brain stem tumors are inoperable. It may be possible to biopsy their external parts, however, to establish an exact diagnosis.

The treatment of choice is radiation therapy to the posterior fossa. An increased number of smaller dosage treatments of radiation (hyperfractionation) is under investigation as a replacement for conventional daily radiation therapy.


The chordoma occurs at the base of the skull or the end of the spine. It is an extradural (outside the dura mater) tumor and usually is benign. However, it frequently invades adjacent bone. This rare tumor represents .2% of all primary CNS tumors. It is found most often in people ages 21 to 40.

Chordomas appear on MRI and CT scans, but a biopsy is necessary to determine an exact diagnosis.

Often, complete surgical resection is possible for the spinal chordoma. A combination of surgery followed by radiation is the usual treatment for skull-base tumors. Because of their proximity to delicate brain structures, charged particle radiation rather than conventional radiation is often used.

Choroid Plexus Papilloma

This is a rare, benign tumor most common in children under the age of 12. About 4% of primary brain tumors in that age group are choroid plexus papillomas. It represents less than 1% of all primary brain tumors.

In children, the most common location of this tumor is the lateral ventricles. The fourth ventricle is the most common site in adults.

Choroid plexus papillomas grow slowly within the ventricles. They eventually block the flow of cerebrospinal fluid. This causes hydrocephalus and increased intracranial pressure.

Both CT and MRI scans detect these tumors.

The treatment of choice is surgery. Tumor removal resolves the hydrocephalus in half of the patients. The remaining patients require a shunt in addition to resection. The rare inoperable or malignant form of this tumor (choroid plexus carcinoma) may be treated with radiation. The choroid plexus papilloma however is generally resistant to radiation therapy (radioresistant).

CNS Lymphoma (Primary Malignant Lymphoma)

In addition to affecting people with healthy immune systems, this disease is common in persons whose immune system is not functioning properly. People with malfunctioning immune systems include those who have undergone organ transplants or those infected with the AIDS virus. The incidence of CNS lymphoma is increasing in people with healthy and unhealthy immune systems.

The most common site of the CNS lymphoma is one of the cerebral hemispheres. Multiple tumors may be present. Metastasis is common.

Symptoms include confusion, lethargy, memory loss, muscle weakness in one area of the body (localized hemiparesis), and seizures.

CNS lymphomas appear on CT and MRI, but exact diagnosis follows a biopsy.

Surgery or biopsy alone may be performed, depending on the exact location, size, and number of tumors. Radiation therapy is often effective as these tumors are responsive to this treatment (radiosensitive). Steroids and chemotherapy may also be used. Temporary blood brain barrier disruption before chemotherapy is under investigation.

Cysts (Dermoid Cyst, Epidermoid Cyst)

Cysts are tumor-like masses.

Dermoid cysts

Dermoid cysts are distinct masses and are almost always benign. The treatment of choice is surgical removal. If they return, growth is very slow and there may be a long interval before any sign of recurrence.

These cysts are more common in the spine than in the brain. The incidence in the brain (intracranial) is greatest in children under the age of 10. Dermoid cysts are most common in the spine in young people between ages 10 and 20.

Dermoid cysts in the brain are usually found in the midline of the cerebellum or the adjacent meninges. The cavity of the fourth ventricle or at the base of the brain on the under surface of the frontal lobes are also common sites.

In the spine, the cysts occur most commonly in the lower end of the spine (lower lumbar area).

Epidermoid cysts

These cysts are more common than dermoid cysts. They are usually benign, but they will slowly recur if not removed completely. Unlike the dermoid variety, they occur more frequently in the brain than in the spine.

Epidermoid cysts are most common in middle-aged adults. The most common sites in the brain for these cysts are the cerebellopontine angle (see figure 3) and the pituitary area.

The treatment of choice is surgical removal.


This is a benign, congenital tumor. It is cystic and occurs primarily in children and adolescents.

Craniopharyngiomas occur in the sellar region. They often involve the third ventricle, optic nerve, and pituitary gland. These are localized tumors that grow by expansion. Malignancy and metastasis are unknown.

Increased intracranial pressure causes many of the symptoms of these tumors. Other symptoms result from involvement of the optic chiasm and pituitary gland. Obesity, delayed development, decreased vision, and a swollen optic nerve (papilledema) are common.

Surgery is the treatment of choice. Radiation therapy for incompletely removed tumors follows. In children younger than 3, radiation is delayed if possible.


Ependymomas arise from ependymal cells, which form the lining of the ventricles and central canal of the spinal cord. Overall, 5% of all intracranial tumors are ependymomas. They represent 9% of all gliomas. The spinal ependymoma accounts for 60% of all gliomas in the spinal cord.

Ependymomas of the cerebral hemispheres occur primarily in children and adolescents.

Benign (low-grade) ependymomas are more common than malig- nant ones. There are three groups of the benign tumors: myxopapillary ependymoma (commonly found in the spine); papillary ependymoma (extremely rare, located in the cerebellopontine angle--see figure 3); and subependymoma [often found in the 4th ventricle and extending into the enlarged space between the cerebellum and the medulla (cisterna magna of the subarachnoid space)]. Anaplastic ependymoma is the malignant form of this tumor. Occasionally these tumors seed to other locations in the centralnervous system.

The usual treatment is surgery followed by radiation therapy. Often, a shunt is necessary to relieve the increased intracranial pressure that frequently accompanies this tumor. Chemotherapy is used for recurrent tumors, and new clinical trials use chemotherapy for initial treatment along with surgery and radiation.

For additional information, refer to the ABTA publication About Ependymoma.

Gangliocytoma (Ganglioneuroma)


These rare tumors arise from ganglia. A ganglion is a group of nerve cells. (Ganglia is the plural of ganglion.) Gangliocytomas are tumors of mature ganglion cells. Gangliogliomas are tumors of both mature nerve (ganglion) and supportive (glial) cells.

These tumors most frequently occur in children and young adults. Tumors arising from ganglia represent .4% of all primary brain tumors.

The most common site is the temporal lobe of the cerebral hemispheres. They may also occur in the spine.

These tumors are small, slow growing, and have distinct margins. Metastasis and malignancy are rare.

Surgery is the treatment of choice.

Glioblastoma Multiforme (GBM)

Glioblastoma multiforme is one of the most malignant and difficult brain tumors to treat. GBM is the most common primary brain tumor of middle-aged adults. GBM represents 30% of all primary brain tumors.

Surgery alone rarely controls the GBM because cells of the tumor stray throughout the brain. Thus, radiation therapy almost always follows surgery or biopsy. Many physicians advocate aggressive chemotherapy as well to control new tumor growth. The GBM is the subject of much research because it is the most common and potentially destructive brain tumor.

While many tumors contain a mixture of cell types, GBM is the most mixed (heterogeneous) of brain tumors. It is this characteristic that makes it difficult to treat. While one cell type is responsive to treatment and dies off, other types are waiting to take over.

Because some systems classify the GBM as a grade IV astrocytoma, you may wish to read the section on high-grade astrocytomas.

For additional information, refer to the ABTA publication About Glioblastoma Multiforme and Malignant Astrocytoma .


This is a general name for tumors that arise from the glial (supportive) tissue of the brain. Gliomas are the most common primary brain tumors. Astrocytomas, ependymomas, oligodendrogliomas, and tumors with mixtures of two or more cell types are the most common gliomas. See Astrocytoma, Ependymoma, Oligodendroglioma, or Mixed Glioma .


This benign, tumor-like mass arises from blood vessels. It is often cystic. There may be single or multiple tumors. Hemangioblastoma represents about 2% of all primary brain tumors. Lindau disease and von Hippel-Lindau disease are hereditary forms of this tumor.

Hemangioblastoma is most frequent in the 35-to-45 age group. The most common site is the cerebellum. It is slow growing and does not metastasize.

This tumor causes increased intracranial pressure and cerebellar dysfunction. Symptoms are headache, vomiting and nausea, gait disturbance, and balance problems.

Both CT and MRI scans are capable of detecting the hemangioblastoma. Angiography is done before surgery to confirm the diagnosis and provide information about the tumor's blood supply.

Surgery is the treatment of choice. Incompletely removed tumors or tumors attached to the brain stem may be treated with radiation therapy.

Inoperable Brain Tumors

Any brain tumor may occur in a part of the brain that is inaccessible to the neurosurgeon. The brain stem, thalamus, motor area, and deep areas of gray matter are often considered to be inoperable areas.

Biopsy alone for diagnosis may be performed if the tumor cannot be removed. Occasionally, even biopsy may not be possible. Treatment is then based on the assumed type of tumor.

Often, radiation and chemotherapy are used to treat high-grade inoperable tumors, or low-grade inoperable tumors which cause severe symptoms. Other low-grade inoperable tumors may require no treatment. Repeat periodic CT or MRI scans are used to follow the progress of these tumors.


See CNS Lymphoma

Medulloblastoma (MDL)

This malignant tumor grows rapidly. It is the second most common tumor in children. Thirty percent of these tumors occur in adults. The MDL is always located in the cerebellum.

Medulloblastoma is an invasive tumor, and it frequently metastasizes to other parts of the central nervous system via the spinal fluid. This tumor may infiltrate the floor of the fourth ventricle and extend into its cavity. It may also infiltrate the meninges. The medulloblastoma may spread (metastasize) outside the brain and spinal cord (central nervous system), although this is uncommon (about 5 - 7%).

Treatment consists of surgical removal of as much tumor as possible. Radiation to the tumor area and the entire brain and spinal cord follows. Very young children are often treated first with chemotherapy. Radiation is delayed until they are older. This tumor is very responsive to radiation therapy (radiosensitive).

"High risk" patients receive chemotherapy as part of their initial treatment. Recurrent tumors may require a second surgery followed by chemotherapy.

For additional information, refer to the ABTA publication About Medulloblastoma.


This benign tumor arises from the meninges. The meningioma represents more than 20% of all primary brain tumors. It commonly occurs in middle-aged adults. The most common sites are the cerebral hemispheres, and the midline. The meningioma also occurs in the spine.

The meningioma is a slow growing tumor with distinct borders. It produces symptoms by compression rather than by invasion of brain tissue.

If the tumor is accessible, the treatment of choice is surgery. Radiation therapy may be of value if the tumor is not entirely resected.

Malignant meningioma is less common. Occurring in the same locations as meningioma, it is difficult to eliminate solely by surgery. Generally, radiation therapy is given either alone or with experimental chemotherapy.

For additional information, refer to the ABTA publication About Meningioma.

Metastatic Brain Tumors

Metastatic brain tumors are tumors formed by cancer cells that arise elsewhere in the body and spread to the brain. Body cancers that frequently spread to the brain include:

  • lung cancer
  • breast cancer
  • colon cancer
  • melanoma
  • kidney cancer

Metastatic brain tumors may appear anywhere in the brain or spine. Multiple tumors frequently occur.

If the primary cancer is under control, surgery is the treatment of choice for single brain tumors. Radiation is the treatment of choice for multiple tumors. Chemotherapy may also be used in addition to either surgery or radiation therapy.

Mixed Glioma

These are tumors that contain a high proportion of more than one cell type. Frequently, the mixed glioma contains both astrocytes and oligodendrocytes, or astrocytes and ependymoma cells.

The behavior of these tumors is similar to tumors composed of the highest grade of cell found in the tumor.

Neurofibromatosis (von Recklinghausen's Disease)

This is a genetic (hereditary) disease. Patients develop skin discolorations and tumors on peripheral nerves (neurofibromas). Brain tumors may also develop, particularly bilateral acoustic neuromas and optic nerve gliomas.

For additional information about neurofibromatosis, contact The National Neurofibromatosis Foundation, 141 Fifth Avenue, Suite 7-S, New York, NY 10010, 212/460-8980.


These are tumors of the supportive (glial) tissue of the brain. They most frequently occur in middle-aged individuals. The most common site is in a cerebral hemisphere. This tumor represents at least 4% of all primary brain tumors.

Oligodendrogliomas frequently contain cells of astrocytoma. Pure oligodendrogliomas are usually slow growing and relatively low-grade, although malignant forms are possible. Often, these tumors are present for many years before diagnosis.

The treatment of choice is surgical removal of as much tumor as possible, followed by radiation therapy. Chemotherapy for oligodendrogliomas is under investigation. Recurrence is not unusual.

For additional information, refer to the ABTA publication About Oligodendroglioma.

Optic Nerve Glioma

Most tumors in this location occur in children under the age of 10. The pilocytic astrocytoma is the most common tumor of this area. These tumors are slow growing. The malignant tumors anaplastic astrocytoma and glioblastoma multiforme may also occur in this location.

The optic chiasm is the most common site. Other frequent locations are one of the optic nerves or the hypothalamus.

Symptoms of tumors in this area include loss of visual acuity, rapid movement of the eyeballs (nystagmus), and "crossed eyes" (strabismus), developmental delay, and abnormal thinness (emaciation).

The MRI is the scanner of choice for diagnosis.

For tumors of one optic nerve, surgery is the treatment of choice. Radiation therapy is the treatment of choice for tumors of the chiasm. Chemotherapy may also be given.

Pineal Region Tumors

The pineal gland is located in the posterior portion of the third ventricle. Pineal region tumors represent less than 1% of all primary brain tumors. However, 3% to 8% of childhood brain tumors occur in the pineal region.

The most common tumor of the pineal region is the germinoma. Germinomas represent over one-third of the tumors in this region. Germinomas of the pineal region are most common in teen-agers.

Additional tumors found in this area include other embryonal type tumors, teratomas, astrocytomas, pineocytomas, and pineoblastomas.

Embryonal tumors in the pineal region are the only brain tumors that may be diagnosed by tumor markers found in the cerebrospinal fluid. The markers are alpha-fetoprotein and beta HCG (human chorionic gonadotropin).

Symptoms are due to obstructive hydrocephalus and involvement of the optic pathways. Headache, nausea and vomiting, lethargy, and double vision (diplopia) are common.

Surgery is possible in some individuals. If surgery is not possible, biopsy alone for diagnosis is performed. The usual treatment for these tumors is radiation therapy. The germinomas in particular are very responsive to radiation therapy (radiosensitive). If hydrocephalus is present, steroids are often prescribed. A shunt procedure may be necessary if the hydrocephalus is not controlled by steroids. Chemotherapy for astrocytomas and germinomas is under investigation.

Pituitary Adenoma

This is a benign, slow growing tumor of the pituitary gland. It represents 8% of all intracranial tumors. Pituitary adenomas most commonly occur in young or middle-aged adults.

The pituitary adenomas are classified as secreting or non-secreting. The majority are secreting tumors and are further classified by the hormone secreted.

If the tumor secretes prolactin, impotence (inability to perform sexual intercourse) in males and

amenorrhea (stoppage of menstruation) and galactorrhea (secretion of milk) in females are common symptoms. This is the most common secreting pituitary adenoma. If the tumor secretes growth hormone (HGH), giantism (excessive size) or acromegaly (enlargement of the extremities: hands, feet) occurs. ACTH secretion causes Cushing's Disease. The rare TSH secreting tumors cause hyperthyroidism (excessive activity of the thyroid gland).

The adenomas often invade the optic chiasm. The most common symptoms of optic chiasm involvement are visual loss and headache.

For secreting pituitary adenomas, complete surgical removal is the treatment of choice. BromocriptineR is a drug that may be used to reduce the size of prolactin-secreting adenomas. For larger, non-secreting adenomas, radiation therapy follows partial surgical removal.

PNET (Primitive Neuroectodermal T umor)

This name refers to a collection of many different brain tumors. All of these tumors contain undeveloped brain cells and are highly malignant tumors. They all tend to spread throughout the CNS. The name PNET encompasses medulloblastomas, the malignant forms of pineal cell tumors, malignant ependymomas, and other tumors. Except for the medulloblastoma, all PNETs are rare.

Surgery followed by radiation therapy is the treatment of choice for these tumors. Radiation therapy is frequently delivered to the entire brain and spine.

Spinal Tumors

The types of tumors found in the spine vary by location.

Locations are defined as follows: (see figures 7 and 8)

TUMOR LOCATION               COMMON TUMOR TYPESExtradural                 Metastatic tumors, chordoma
(outside the dura mater)
Intradural (beneath the dura mater)Extramedullary
                    Schwannoma, meningioma
(outside the spinal cord but inside the dura)
Intramedullary                   Astrocytoma, ependymoma
(within the spinal cord)

Primary spinal cord tumors are most often intradural and extramedullary.

Some symptoms of spinal tumors are due to compression of the spinal cord and usually have a gradual onset. Muscle weakness is common. If the tumor infiltrates the spinal cord, pain is common.

Treatment of spinal tumors depends on whether the tumor is primary or metastatic, its exact location and type. Surgery is the treatment of choice for intradural, extramedullary tumors. Malignant, partially resected, or inoperable tumors are treated with radiation therapy. Chemotherapy may also be used.


See Ependymoma

Tuberous Sclerosis (Bourneville's Disease)

This is a hereditary disease involving the skin, heart, kidney, and nervous system. It is more common in males than females. The disease becomes obvious in childhood.

Subependymal giant cell astrocytoma is the ventricular tumor associated with tuberous sclerosis. It is a benign tumor. The foramen of Monro is the most common location. This tumor occurs in half the patients with tuberous sclerosis.

For more information about tuberous sclerosis, contact the National Tuberous Sclerosis Foundation, 8000 Corporate Drive, Suite 120, Landover, MD 20785, 1-800-225-6872.

SECTION 7 How are brain tumors treated?


Treatment of a brain tumor is different from treatment of tumors in other parts of the body. First, brain surgery requires far more precision and highly sophisticated instruments. Second, the brain itself prevents many therapeutic drugs from entering it. Third, both the therapies used to treat brain tumors and side effects of these therapies are quite complicated. Experienced, multi-disciplinary medical professional teams offer the most up-to-date treatment opportunities.

The brain tumor specialist recommends one or several treatment methods based on information from the various diagnostic tests.

The patient, family, and health-care providers discuss the plan of treatment. Probable outcome (prognosis), the patient's current health status, goals for treatment, and issues concerning quality of life are all considered. The discussion includes an outline of future treatment options and information about available support services.

Treatment modalities include surgery, radiation therapy, chemotherapy, immunotherapy, or a combination of these treatments.


Surgery is the treatment of choice for accessible brain tumors. Accessible tumors are those which can be surgically removed without causing severe neurological damage. Tumors located in gray matter or deep within the brain may be inaccessible.

The goal of surgery is to remove all visible tumor. Many benign tumors are treated only by surgery. Most malignant tumors require additional treatment. Malignant tumors lack distinct borders. They often invade nearby normal brain tissue. Tumor cells may also spread throughout the brain and spine by way of the cerebrospinal fluid. But, even partial tumor removal is beneficial.

The purpose of surgery is:

  • to remove as much tumor as possible
    • partial removal (debulking) of a tumor provides relief of symptoms, improved quality of life, and a smaller tumor burden for other treatment modalities
  • to help establish an exact diagnosis
    • removal of a sample of tumor to be examined under a microscope in the laboratory provides an exact diagnosis
  • to determine the extent of the tumor
    • the neurosurgeon sees the actual tumor in the brain
  • to provide access for other treatments, such as newer forms of radiation
    • during surgery, implants may be placed or radiation may be delivered

Biopsy alone is performed when the tumor is inoperable or when surgery must be delayed. Resection (surgical removal of a tumor) is the treatment of choice whenever possible.

Biopsy (Surgical removal of a sample of tumor)

Biopsy is the removal of a small quantity of tumor for microscopic examination to determine an exact diagnosis. Needle biopsy uses a narrow, hollow needle. A small hole (called a burr hole) is drilled in the skull and the needle passes through the hole under CT guidance (stereotaxic biopsy). Tumor tissue is removed from the core of the needle. Stereotaxic biopsy is more exact than free-hand biopsy, and is considered by many practitioners to be safer. This technique is usually available at major medical centers.

Resection of a Tumor

If the tumor is accessible and the patient's general health is good, resection is the treatment of choice. The goal of surgery is to remove as much tumor as possible.

The most commonly performed surgery for removal of a brain tumor is a craniotomy. The neurosurgeon makes an incision into the scalp. Removal of a piece of bone exposes the area of brain over the tumor. Location and removal of the tumor then takes place. After resection and bone replacement, the skin is sewn together. Sometimes, replacing the bone is not necessary. For example, the muscles in the back of the head are very strong and can protect the brain by themselves.

The neurosurgeon has a wide choice of tools to use in removing brain tumors. Commonly used tools are the surgical laser, ultrasonic aspirator, and operating microscope. Other tools include evoked potentials, ultrasound imaging, and stereotactic apparatus. Usually, all of these surgical tools are available at major medical institutions. The tools used for surgical removal depend on the type of tumor and its location.


Stereotactic localization

This technique is used for needle biopsies, laser microsurgery, and implantation. It provides precise information about tumor location without direct visual access. Stereotaxy provides a three-dimensional map of the brain.

During surgery, a rigid frame holds the patient's head in place. Attached to the frame is a scanning device which accurately pinpoints the location of the tumor.

Laser microsurgery

The laser is a surgical tool. It may be used in addition to or in place of a scalpel. The laser is capable of immense heat and power when focused at close range. It destroys tumor cells by vaporizing them. The laser is frequently used with stereotactic localization.

Ultrasonic aspiration

This tool uses ultrasonic waves to cause vibration. The vibration breaks the tumor into small pieces. The pieces are then aspirated (sucked out).


Many tumors are radiosensitive--their cells readily die when exposed to radiation. Conventional radiation therapy uses external beams of either x or gamma rays aimed at the tumor. The therapy is given over a period of several weeks.

Other types of radiation also are available. One of these is interstitial radiation--implanting radioactive seeds directly into a tumor. Stereotactic radiosurgery delivers a high, single dose of radiation to a small, well-defined area. Another technique is photodynamic therapy. A light sensitive drug is given through a vein and concentrates in the tumor. Then, during a surgical procedure, a special light activates the drug. Hyperthermia uses heat to kill tumor cells. Also available are other forms of radiation energy, dosages, and schedules.

For additional information, refer to the ABTA publications Radiation Therapy of Brain Tumors: Part I and Part II.


Chemotherapy uses special chemicals to poison tumor cells. Tumor cells are more vulnerable to these chemicals than healthy cells. Chemotherapy may be used before, during, or after surgery and radiation therapy. Recurrent tumors are treated with chemotherapy as well. In very young children, chemotherapy is used to delay radiation therapy.

Many drugs have anti-brain tumor activity. But it is difficult to predict which tumors will respond to which chemicals and to what degree. For this reason, treatment often consists of a combination of drugs.

Some treatment methods include drugs that help other drugs reach the tumor in greater concentration.

The blood-brain barrier is a natural mechanism that protects the brain. It inhibits certain classes of drugs from reaching tumor cells. MannitolR disrupts the blood-brain barrier temporarily. Other methods used to increase drug delivery to tumor are drug injection into an artery or spinal fluid, reservoirs and pumps, or the surgical placement of drug-saturated wafers.

Certain chemicals are used to make other treatments more effective. For example, radiosensitizers are thought to make radiation therapy more effective.

For additional information, refer to the ABTA publication Chemotherapy of Brain Tumors.


Steroids control the swelling due to accumulation of fluids (edema) often associated with brain tumors. Dexamethasone (DecadronR), prednisolone, and prednisone are examples of these drugs. Steroids may be used temporarily following surgery or during radiation because these treatments often cause edema. Long-term use is for relief of symptoms. Because of the potential side effects of this class of drugs, long-term use requires close monitoring.


The immune system is the body's natural defense against disease. Immunotherapy uses biological response modifiers (BRMs)to fight tumor cells. BRMs are substances that either kill tumor cells directly or stimulate production of other substances to control tumor growth. Immunotherapy researchers study the response of the body to a tumor and the events that allow a tumor to grow.

Research in a variety of areas holds much promise for future treatment. Experimentally, several biological response modifiers now are in use. Laboratory studies explore other substances.

The routine use of immunotherapy is possible in the future.

For additional information, refer to the ABTA publication Immunotherapy of Brain Tumors.


Oncogene research may eventually lead to new treatments for or the prevention of brain tumors. It is an active area in cancer research.

Proto-oncogenes are normal genes that direct normal growth and development. Alterations in proto-oncogenes may activate them into oncogenes. Oncogenes cause cancer. Activation probably requires a series of events. Research seeks to identify oncogenes and determine what activates them.

SECTION 8 Figures

Figure 1: Meninges and ventricles of the brain

Figure 2: Functions of the cerebral hemispheres

Figure 3: View from the bottom of the brain

Figure 4: Lateral view of the brain and spinal cord

Figure 5: Cross section of the head

Figure 6: Cranial Nerves

Figure 7: Cross section of vertebra and spinal cord

Figure 8: Spinal cord and nerve roots


We are extremely grateful to the literally thousands of people whose generosity has made this Primer possible. We express particular appreciation to those who contributed their time and talents:

Gail Segal, Medical Writing, Chicago, Illinois

Victor A. Levin, MD Technical Review, Department of Neuro-Oncology, University of Texas, M. D. Anderson Cancer Center, Houston, Texas

Barbara Steiger, Manuscript Editin,g Highland Park, Illinois

Marv Glick Design, Graphic Design, Chicago, Illinois

Diane Falk, Medical Illustration, Zion, Illinois

To learn more about American Brain Tumor Association, contact the office at 847-827-9910, or the Patient and Family Line: (800) 886-2282, or by email:

Return to the ABTA Homepage

Disclaimer About Medical Information: The information and reference materials contained herein is intended solely for the information of the reader. It should not be used for treatment purposes, but rather for discussion with the patient's own physician. All visitors to this and associated sites from the Neurosurgical Service at MGH agree to read and abide by the the complete terms of legal agreement found at the Neurosurgery "disclaimer & legal agreement." See also: the MGH Disclaimer, the MGH Privacy Policy, and the MGH Interactive Program Disclaimer - Copyright 2006.
MGH  Neurosurgical Service Home
Research@NeurosurgeryVisitors must read the disclaimer - legal agreement.
All Rights Reserved. Copyright 20006 MGH Neurosurgical Service

(internal access only)
System Info Contact: PageServant or e-mail C.Owen