A tumor is the abnormal, spontaneous growth of new tissue. Tumors are either benign (do not spread to other tissues or parts of the body) or malignant (cancerous tumors that invade other tissues and parts of the body). Nervous system tumors can develop in either the brain or spinal cord, although spinal cord tumors are rare.
Benign tumors and cancerous tumors at the site of origin are referred to as primary tumors. Tumors that develop somewhere other than the site of origin are called a metastatic tumors.
More than 100,000 people in the United States are diagnosed with a brain tumor each year, and the numbers are increasing. In most cases, th cause for the brain tumor is unknown. Because of the incredible complexity of the human brain and its role in the normal function of the body, brain tumors often have incapacitating consequences.
Surgery and radiation are the most common treatments for brain tumors, although the effectiveness of these treatments may be limited by the risk for damage to healthy brain tissue.
About 44% of all primary brain tumors are benign. Although these tumors do not spread, they are serious, can recur after they have been removed, and can cause death.
Malignant brain tumors are the second leading cause of cancer death in young adults under the age of 34, young children under the age of 15, and people over the age of 65.
Signs and Symptoms
A tumor is a mass of cells that grows over time and expands inside the brain. This expansion causes two general types of symptoms: increased pressure inside the head (intracranial pressure) and disrupted brain function. The increased intracranial pressure can result from the growing tumor itself, swelling associated with metastatic tumors, or hydrocephalus (a swelling caused by the accumulation of too much cerebrospinal fluid) obstructing the normal flow of cerebral spinal fluid. The common symptoms that patients notice are headache, nausea and vomiting, general confusion and lethargy. When the function of the brain is disrupted by localized problems associated with a tumor, symptoms include seizures, speech and language problems, visual problems, or general weakness. The particular symptom often reflects where in the brain the tumor is located.
The various symptoms of neurological dysfunction occur no matter how slowly or quickly the tumor grows. In slow-growing tumors, however, the brain can sometimes accommodate for the growth of the tumor, and the symptoms may be less pronounced. When the tumor grows rapidly, the symptoms may occur very suddenly and intensely. The most common symptoms of a brain tumors include particular kinds of headache, seizures (especially in adults who have never experienced seizures before), nausea and vomiting (especially when it's coupled with another symptom), a change in cognitive abilities (ability to perceive, reason and remember), and a wide range of neurological abnormalities depending on where in the brain the tumor is located.
A new pattern or type of headache is the first noticeable symptom for about 20% of all people with brain tumors. Eventually, headaches will occur in over 60% to 70% of all patients at some point in the course of their illness. The headache often is on the same side of the tumor but may be located anywhere on the head. Many headaches associated with brain tumors tend to be located on the frontal areas of the head (forehead/top of head). This happens not because the tumor is there but rather that is where the pain is referred (referred pain is pain that is felt somewhere different from where it originates).
Headaches caused by brain tumors are usually nonthrobbing and worse in the morning after laying flat all night, because pressure in the brain increases when the head is down. They may be worse with exertion. Most patients describe nausea and vomiting with the headache. If the tumor is obstructing the ventricles, the structures that contain the cerebrospinal fluid, the headache may get worse when a person changes position.
A seizure is a sudden, brief attack of uncontrolled motor activity or altered consciousness. Seizures occur in approximately 35% of all brain tumor patients. The probability of having a seizure depends on the location of the tumor, as some parts of the brain are more prone to seizure activity than others. Some seizures may be partial, and involve only a single site in the brain. Others can affect the whole brain and result in loss of consciousness.
Nausea and Vomiting
When a person develops a new pattern of headaches in the morning coupled with vomiting, they should be further evaluated for the presence of a brain tumor. Even if this particular pattern doesn't develop, many people with brain tumors eventually develop chronic nausea and loss of appetite, which are presumably associated with the increased intracranial pressure (pressure within the skull compartment).
Change in Cognitive Status
Patients with tumors often develop early changes in their cognitive abilities. These include difficulties remembering things, changes in personality or mood, lack of initiative, and poor judgement. Depending on where the tumor is located, a person may have reading, writing or speaking difficulties. It may be very difficult for some folks to engage in abstract reasoning, and some people may not be able to make decisions. Many people with brain tumors suffer from sleep disorders and restlessness and are unable to concentrate.
Motor and Sensory Abnormalities
The specific neurological abnormalities that a person with a brain tumor experiences vary from person to person and depend on where in the brain the tumor is located. For example, if the tumor invades the motor regions of the brain (areas responsible for movement of the skeletal muscles, such as those in the arms and legs), patients can show signs of motor weakness on the opposite side of the body (one side of the brain controls the opposite side of the body). The arms and legs on the opposite side of the body may be stiff or move awkwardly.
When the areas of the brain responsible for sensing the environment - the sensory structures - are damaged, a person may feel tingling, numbness, or other odd sensations. People may not be able to recognize parts of their environment. For example, if the tumor obstructs the visual pathways, in addition to vision loss, patients may not be able to recognize objects by looking at them. If the tumor is in the temporal lobe of the brain, a person may see hallucinations or experience other unusual perceptions. If the tumor is in the frontal lobe, a patient may have bowel and bladder problems.
There are two main types of brain tumors: primary brain tumors that originate in the brain, and metastatic brain tumors that originate from cancer cells that have come from other parts of the body. Primary tumors can be either benign (noncancerous) or malignant (cancerous). Malignant tumors in the brain are life-threatening, because they are aggressive and invasive in nature.
Slow-growing benign tumors in the brain also can have life-threatening consequences, depending on the type of tumor and its location. This is because the skull is a closed, and when a brain tumor takes up space, it can compress vital tissues and structures and cause serious neurological problems. Some brain tumors are easier to remove and treat than others.
Brain tumors are classified according to the type of cell that makes up the tumor, or the cell type from which the tumor originated. Gliomas are tumors that are made up of glial cells (cells that provide important structural support for the nerve cells in the brain). An astrocyte is one type of glial cell, and the tumors that grow out of astrocytes are called astrocytomas.
Meningiomas are tumors of the meninges, the membranes covering the brain. Pituitary adenomas are tumors that start in the anterior pituitary (gland at the base of the brain that secretes hormones important for growth and reproduction).
Lymphomas are tumors made up of lymph cells (lymph is a fluid that flows through all the tissues of the human body and plays an important role in cleaning out bacteria and other foreign matter). Metastic tumors are brain tumors that have originated elsewhere in body and have metastasized to the brain. In addition to being classified on the basis of cell type, malignant tumors are typically assigned a tumor grade, based on what the cancer cells look like under a microscope.
Primary Brain Tumors Gliomas
Gliomas are tumors that are made up of glial cells, cells that play an important structural role in the brain. There are several types of gliomas and the two most common are astrocytomas, cancerous tumors, and oligodendrogliomas - rare, usually benign tumors. A particularly malignant type of astrocytoma is known as a glioblastoma multiforme, which can be either low grade (slow-growing and not very aggressive) or high grade (fast-growing and very aggressive).
About 25% of all brain tumors are astrocytomas, malignant tumors that originate in cells called astrocytes. Astrocytomas are graded and named based on what the cells look like under the microscope. Low-grade astrocytomas are made up of the least aggressive cancer cells, anaplastic astrocytomas are made up of more aggressive cancer cells, and a glioblastoma multiforme is a type of astrocytoma that is made up of extremely aggressive cancer cells. Glioblastoma multiforme is the most common adult primary tumor.
Astrocytomas usually develop between the ages of 20 to 50, but they can occur at any age. One of the most common early symptoms is seizures. Although they can develop anywhere in the brain, they usually develop in the temporal or frontal lobes of the brain and then spread into the adjacent tissues.
Glioblastoma multiforme, a type of malignant astrocytoma, are the most common adult primary brain tumors. They occur slightly more frequently in men. Patients with these types of tumors are usually over the age of 50, but the tumors can develop at any age. Patients who develop the tumor at a younger age have a significantly better survival rate than older patients. Symptoms are caused by rapid tumor growth, infiltration into adjacent tissues, swelling (edema) and an increased accumulation of cerebrospinal fluid in the brain (hydrocephalus). Most patients experience headaches, seizures, or a change in their mental status.
Less than 5% of all brain tumors are oligodendrogliomas, tumors that originate in cells called oligodendrocytes. The average age of patients with these kinds of tumors is arbout 40 years old. Oligodendrogliomas are very slow-growing, usually benign tumors (less than 10% are malignant), and they occur most often in the frontal lobes. The first symptom for many patients is a seizure.
There are two types of oligodendrogliomas: low-grade oligodendrogliomas are made up of less aggressive cells, and anaplastic oligodendrogliomas are made up of more aggressive cells. More common than either low-grade or anaplastic oligodendrogliomas, however, are tumors made up of a mix of oligodendrioglioma and astrocytoma. These mixed-cell tumors are called oligoastrocytomas.
Less than 5% of all brain tumors are ependymomas, which usually occur in the lining of the ventricles, the structures in the brain that contain the cerebrospinal fluid. They also occur in the lining of the middle part of the spinal cord. One of the earliest symptoms is hydrocephalus, an increased accumulation of cerebrospinal fluid that causes swelling and neurological dysfunction.
The pituitary gland is a small structure at the base of the brain that produces hormones necessary for normal growth and metabolism. Tumors in the pituitary gland are called pituitary adenomas, benign tumors that account for about 10% to 20% of all brain tumors.
There are two types of pituitary adenomas: secreting and nonsecreting. A patient with a secreting pituitary adenoma has abnormally high levels of pituitary hormones circulating through their body, which in turn causes a range of symptoms from impotence (erectile dysfunction) to amenorrhea (the abnormal ending of menstruation). For example, one of the more common types of pituitary adenomas produces and secretes excess prolactin, a substance responsible for triggering milk production when a woman is nursing.
In addition, because the pituitary gland is located near important visual pathways, a patient with a pituitary adenoma may experience vision loss.
The meninges is the thin outer covering that lines the spinal cord and brain. It is made up of three layers: the dura matter (external), the arachnoid (middle) and the pia matter (internal). Tumors that originate in the meninges are called meningiomas.
About 15% to 20% of all brain tumors are benign, slow-growing meningiomas. Even though they are benign, they can still cause severe neurological dysfunction. Patients often suffer seizures, headache, weakness, and visual problems. They occur more commonly in women and after the age of 40. Patients with neurofibromatosis, a genetic disorder that predisposes to certain types of tumors, are at a greater risk for developing meningioma. Patients who have had previous brain radiation are also at a greater risk for developing meningioma. Many patients with meningiomas seem to have a genetic defect on chromosome number 22.
Nerve Sheath Tumors (Schwannomas)
Nerve sheath tumors, also known as schwannomas, are tumors that originate in the Schwann cells that make up the protective sheath that surrounds the nerve fibers. Schwannomas are usually benign and slow-growing. One of the most common types is known as a vestibular schwannoma, or acoustic neuroma. Another common schwannomas causes facial paralysis.
Acoustic neuromas are schwannomas that involve the eighth cranial nerve. There are a total of 12 pairs of cranial nerves that originate in the brainstem (the bottom part of the brain that connects to the spinal cord) and lead to various parts of the face and neck. The eighth cranial nerve is responsible for balance and hearing. Acoustic neuromas cause early hearing loss in the ear on the side of the tumor, tinnitus (ringing in the ears), vertigo (dizziness), balance problems, and facial weakness. These tumors occur most commonly in people between 30 and 50 years old but can occur anytime.
Metastatic Brain Tumors
Cancerous tumors that spread to the brain from other parts of the body, such as the lung, are said to be metastatic. Tumor cells spread to the brain through the bloodstream. In more than half of all metastatic brain cancer, the tumors are found throughout the brain and are not localized to one particular spot, making them extremely difficult to treat. Between 20% to 40% of all cancer patients develop metastases to the brain. In adults, the most common types of cancer to spread to the brain are lung, breast, gastrointestinal, and urinary/genital tract cancer, as well as malignant melanoma.
The main symptoms of metastatic brain tumors include seizures, headaches, weakness and confusion. In general, the prognosis for patients who develop brain metastases is poor.
Spinal Cord Tumors
Primary spinal cord tumors are very rare and usually benign. Only about 1 in 200 newly diagnosed tumors are spinal cord tumors. Of these, less than 3% are malignant, or cancerous. Spinal cord tumors are made up of the same types of cells that make up brain tumors. For example, they include meningiomas and gliomas. Most malignant spinal cord tumors, again of which there are very few, are tumors that originate from cancer cells that come from other parts of the body.
The spinal cord has only a limited amount of space inside the spinal column (the backbone or spine), so even a very small tumor can cause enough pressure to become problematic. Though sometimes the tumor grows so slowly that the spinal column is able to adapt to it and make room for it such that a person suffers very few symptoms. Very aggressive metastatic spinal cord tumors can cause paralysis very quickly - even within days. Slow-growing tumors can also cause paralysis if left untreated.
Surgery is the usual course of treatment for primary spinal cord tumors. Metastatic spinal cord tumors are not always treated surgically, however, especially if there is more than one metastasis. Although often surgery may be used as a way to relieve pain and other symptoms, even though it may not actually involve removing the tumor.
The first step in diagnosing a brain tumor involves evaluating the patient's symptoms and medical history. Diagnostic tests that may be performed to confirm the diagnosis, from a neurological exam, to computer imaging techniques, to surgical biopsy.
A neurological exam involves checking the patient's eye movements and reflexes, hearing, balance and coordination, movement, and various other sensations. Any obvious abnormalities in how a person senses the environment or how they move may suggest a neurological problem.
To help determine if the problem is a result of a brain tumor or another neurological condition, special imaging techniques are used to observe the brain and detect any abnormal tumor mass.
CT (computed axial tomography) scan involves using an x-ray machine and computer to obtain a computer image of an area of the body. Often, a dye is injected to improve the contrast between abnormal and normal tissue. In some cases, this test can be used to determine the type of tumor. MRI (magnetic resonance imaging) uses magnetic fields and a computer to obtain an image of the brain. This test produces more detailed images than CT scan, especially when tumors are located near bony structures. MRI scans provide images at various angles and are very useful for detecting swelling (edema) of brain tissue and bleeding (hemorrhage). As with CT scan, dye can be injected to improve the contrast between abnormal and normal tissue. PET (positron emission tomography) is used to measure brain activity. In this test, substances that can be monitored and used to evaluate tumor growth are injected. PET may be helpful in detecting recurrent tumors and in evaluating responses to chemotherapy and radiation treatment.
A biopsy is the surgical removal of a small part of the tumor tissue to identify the exact type of tumor. Stereotactic biopsy uses computer guidance to determine the precise location of the tumor.
Using stereotactic technology, only a very small hole in the skull must be made. Prior to stereotactic surgery, a very wide opening in the skull was required for biopsy (called an open biopsy).
The complication rate for stereotactic brain biopsies is very low, and a correct diagnosis is made in more than 90% of cases. Sometimes, an open biopsy is necessary.
Tissue removed during biopsy is sent to a laboratory and is prepared and studied under a microscope by a pathologist. Based on the appearance of the cells and other characteristics, the type of tumor can be determined. If the tumor is malignant, the grade (i.e., how aggressive and fast-growing it is) can be determined.
Treatment for brain tumors usually involves a combination of surgery, radiation and chemotherapy. The first goal of treatment is to remove as much of the tumor as possible, without damaging the surrounding normal brain tissue. Factors such as the patient's age, general health, occupation, and personal choice, all play a role in determining a course of treatment.
Some nervous system tumors can be treated surgically and others cannot. Sometimes there are several different surgical procedures for a particular type of tumor. Sometimes a tumor can be treated with radiation alone, and does not need to be surgically removed.
In most cases, a multidisciplinary team of medical specialists work together to contribute to a patient's treatment.
For patients undergoing brain tumor surgery, it is important to perform certain medical tests beforehand to provide the safest possible surgery. All patients should be in generally stable medical condition.
Patients over the age of 40 should have an EKG and chest x-ray, as well as several other tests to evaluate factors such as blood pressure and diabetes. If the patient has uncontrolled hypertension or diabetes, their blood exhibits anticoagulation, or they have active coronary ischemia, surgery usually is not done.
Surgery is used to diagnose and treat brain tumors. Complications occur in less than 5% of cases, and depend on the type of tumor andof cerebrospinal fluid.
Most types of surgery involve temporarily removing a section of the skull, opening the dura (outer membrane that covers the brain), and then removing the tumor and replacing the bone.
New surgical techniques include stereotactic biopsy or surgery that use computer guidance to exactly locate and either biopsy or remove the tumor, endoscopic surgery, laser surgery, and surgery under local anesthesia.
The word stereotactic comes from Greek and Latin words meaning "three dimensions" and "to touch." This technique utilizes CT scan and MRI scan of the brain to find the exact location of the tumor. A special frame is placed on the patient's head and only a very small hole is drilled through the skull. Stereotactic surgery reduces the rates of complications normally associated with performing an open resection (cutting or removing a tumor) in the brain, which involves cutting a wide opening in the skull. With computer guidance, the neurosurgeon is able to operate very precisely.
Endoscopic surgery is a type of surgery used to remove pituitary adenomas. In the past, pituitary adenomas were removed by making an incision in the mouth, beneath the upper lip, and then using a microscope to look up through the tissue to the base of the skull where the pituitary gland is located. With an endoscope, the tumor can be removed without any incision at all. Instead, the surgeon goes through the nose and is able to reach and remove a tumor in the pituitary gland through existing nasal channels. This procedure is less painful and has a quicker recovery time. Other tumors that are at the base of the skull can also be removed using endoscopic surgery.
The use of lasers (light amplification by stimulated emission of radiation) allows a surgeon to remove diseased tissue by aiming a beam of concentrated light on it rather than using a scalpel to cut it away. Laser surgery is often used following traditional surgery to remove any residual tumor tissue.
Surgery under Local Anesthesia
Surgery under local anesthesia involves the use of brain mapping techniques. A brain mapping technique that allow a surgeon to operate in sensitive areas of the brain, such as those that control motor function or speech. Small electrodes can be used to stimulate specific pathways so that the nerve response can be measured and a surgeon can determine the function of the nerve. The patient is awake during surgery.
Postoperative care includes drug therapy with corticosteroids, histamine inhibitors (blocking stomach acid), and antiepileptics. Sometimes patients may need to visit a postoperative rehabilitation facility. Corticosteroids (dexamethasone and Decadron) help reduce swelling and can relieve various postoperative neurological effects.
Most malignant brain tumors are treated with external-beam radiation even if the entire primary tumor is surgically removed, because often there are hidden tumor cells still left in the brain tissue.
For benign tumors, radiation is usually applied when the entire primary tumor cannot be surgically removed.
For malignant tumors, radiation more than doubles the survival rate for patients with anaplastic astrocytomas and glioblasoma multiformes, and it can prolong survival for patients with low-grade gliomas.
External Beam Radiation
External beam radiation is the traditional form of radiation therapy. It delivers radiation from outside of the body, usually a couple of weeks following surgery. It is typically applied at regular intervals for several weeks.
Hyperfractionation is a modified form of external beam radiation that involves applying less intense but more frequent doses of radiation, to which some patients respond more readily.
New Types of Radiation Therapy: Stereotactic Techniques
New types of radiation that are being used to treat brain tumors include stereotactic radiosurgery or radiotherapy, as well as brachytherapy. Stereotactic radiosurgery involves using focused radiation on a localized spot in a single dose. Even though it is called "radiosurgery," it does not involve actual surgery. A head frame, to which a CT or MRI scanner is attached, is attached to the patient's skull, and with the aid of the computer imaging, the radiologist is able to pinpoint the tumor and aim the radiation directly at it.
There are new stereotactic techniques that do not involve the use of the head frame. Often the radiation comes from several different directions and hits the tumor at various angles. The advantage of such localized radiation is that the surrounding, healthy tissue is left undestroyed.
It is often used in addition to external beam radiation, especially for malignant gliomas and mestastases that are in deep or sensitive areas of the brain where surgical removal is potentially dangerous. Some tumors, however, cannot be treated with such intense local radiation. The optic nerves are especially sensitive to radiation, so tumors near the optic nerves are better treated with several small doses rather than one big blast.
Stereotactic radiotherapy involves applying many small doses of radiation to a local spot, using the same imaging techniques that stereotactic radiosurgery requires. Brachytherapy involves implanting capsules that contain radioactive substances into the tumor.
There are various other radiation techniques, some of which are being used on an experimental basis. Other technologies include the use of medications or other compounds that may make tumor cells more sensitive to radiation.
Chemotherapy is not used for benign tumors and is not used for most malignant brain tumors, which are treated with radiation and/or surgery. The problem with chemotherapy is that it works by interrupting mitosis, the process of cell division. Many brain tumors are already slow-growing, so slowing down the process of their growth and division by chemotherapy does not do much good.
Another problem with using chemotherapy to treat brain tumors is finding or developing drugs that effectively cross through the blood-brain barrier and get to the place in the brain where they need to be in order to do any good.
One drug that has proved to be effective is BCNU. A new technique enables neurosurgeons to place a wafer soaked with BCNU into the surgical cavity after the tumor has been removed. By applying it directly into the tumorous region of the brain, side effects are limited and the drug has a more beneficial effect. Some tumors are treated by injecting drugs directly into the spinal fluid.
Overall, studies have shown that patients who receive chemotherapy for malignant tumors show improved survival compared to those who do not receive the chemotherapy. The effectiveness of chemotherapy depends on the tumor type (medulloblastomas, anaplastic astrocytomas and glioblastomas respond to varying degrees to certain drugs). Chemotherapy is often used in very young children to delay radiation therapy as long as possible. Some meniongiomas respond to anti-progesterone agents. Most mestastatic brain tumors do not respond to chemotherapy, although there are exceptions. With metastatic brain tumors, the best chemotherapy agent is usually the one that has been the most effective with the primary cancer.
There are many experimental treatments, ranging from novel chemotherapy agents to drug therapy to new ways of applying radiation. As with any serious illness, it is generally a good idea to get a second or third opinion and gather as much information as possible about treatment.
When brain tumors do not respond to surgery, radiation, or chemotherapy, other treatments may be used. These treatments may include the following:
There are three types of astrocytoma tumors: low-grade astrocytoma, anaplastic astrocytoma, and glioblastoma multiforme.
Low-grade astrocytomas are typically removed surgically. It is not clear if radiation following surgery provides any benefit for low-grade tumors. It may be enough to monitor the recurrence of tumor growth with MRI or CT scan.
More aggressive anaplastic astrocytomas and glioblastoma multiformes usually are treated using surgery and radiation therapy, followed by chemotherapy. Various chemotherapy agents are currently being studied in clinical trials.
Glioblastoma multiforme, which is the most common adult primary tumor type, is especially difficult to treat because it tends to infiltrate normal brain tissue, preventing complete surgical removal.
Low-grade oligodendrogliomas (low-grade tumors) and oligoastrocytomas (tumors made up of a mix of oligodendroglioma cells and astrocytoma cells) are typically removed surgically, sometimes followed by radiation. The more aggressive anaplastic oligodendrogliomas are usually treated using chemotherapy, followed by radiation.
Treatment of Spinal Cord Tumors
Primary spinal cord tumors do not usually require radiation, unless they cannot be removed surgically. Metastatic spinal tumors, however, are normally treated using radiation as the primary therapy. Healthy spinal cord tissue is extremely sensitive to damage caused by radiation, even more so than brain tissue and about half of all spinal cord tumors occur in the thoracic region, which is the most sensitive area.
Chemotherapy is sometimes used to treat spinal cord tumors, after surgery or radiation or when surgery or radiation are not recommended. Because spinal cord tumors can cause significant disability, rehabilitation and pain management are both an important part of treatment.
Because of the effects of nervous system tumors or treatments, rehabilitation is often an important part of recovery. Occupational rehabilitation involves restoring the patient's normal daily functioning, from working with the hands to driving.
Physical therapy involves improving strength and motor function. Speech and language therapy may be used to restore the patient's ability to speak clearly and cognitive therapy can help the patient with short-term memory loss.
Specialists can help patients with vision, balance, or facial paralysis. Vocational therapy can help the patient re-enter the workplace.
An important part of living with and recovering from a nervous system tumor is emotional well-being. Many patients benefit from joining a support group and/or seeing a counselor or psychotherapist to deal with stress and emotional challenges. Maintaining a positive attitude, exercising regularly, and eating a healthy diet are important parts of feeling well.
Because loss of pituitary function can be a long-term side effect of radiation therapy, endocrine evaluation may be an important part of follow-up care for patients who have received radiation. Neuropsychological testing may also be done to evaluate intellectual activity following brain tumor radiation.
A good resource for information and contacts about brain tumors is the Brain Tumor Society. This organization can provide information to patients and families about medical resources and emotional support. The telephone support line is 1.800.770.8287.