Brain Tumors

A brain tumor is a noncancerous (benign) or cancerous (malignant) growth in the brain, whether it originates in the brain or has spread (metastasized) to the brain from another part of the body.
Brain tumors are equally common among men and women, but some types are more common among men and others are more common among women. Brain tumors are occurring with increasing frequency among older people.
Brain tumors may be primary or secondary. Primary brain tumors originate in the cells within or next to the brain. These tumors may be cancerous or noncancerous. Secondary brain tumors are metastases originating in another part of the body and thus are always cancerous.
Noncancerous tumors are named for the specific cells or tissues in which they originate. For example, hemangioblastomas originate in blood vessels ("hema" refers to blood vessels, and hemangioblasts are the cells that develop into blood vessel tissue). Some noncancerous tumors that originate in embryonic cells may be present at birth.
Most commonly, cancerous brain tumors are metastases from cancer that started in another part of the body. Metastases may grow in a single part of the brain or in several different parts. Many types of cancer-including breast cancer, lung cancer, cancer in the digestive tract, malignant melanoma, leukemia, and lymphoma-can spread to the brain. Lymphomas of the brain are common among people who have AIDS and, for unknown reasons, are becoming more common among people who have normal immune systems. The most common type of primary cancerous brain tumor is a glioma.

Symptoms
Symptoms occur whether a brain tumor is noncancerous or cancerous. A brain tumor can cause many different symptoms, and symptoms may occur suddenly or develop gradually. Which symptoms develop first and how they develop depend on the tumor's size, growth rate, and location. In some parts of the brain, even a small tumor can have devastating effects. In other parts of the brain, tumors can grow relatively large before any symptoms appear. At first, the tumor pushes and stretches nerve tissue, which can compensate for these changes very well, so symptoms may not develop at first. Symptoms develop when brain tissue is destroyed or the pressure within the skull (intracranial pressure) increases, compressing the brain. Pressure may increase because the tumor is enlarging. Eventually, any brain tumor can increase pressure within the skull.
When the brain tumor is a metastasis from cancer in another part of the body, a person may also have symptoms related to that cancer. For example, a person with a metastasis from lung cancer may have a cough that brings up bloody mucus in addition to symptoms of a brain tumor.
A headache is often the first symptom, although most headaches are not caused by brain tumors. A headache due to a brain tumor usually recurs more and more often as time passes. It eventually becomes constant without relief. It is often worse when the person lies down and may awaken the person from sleep. A gradually growing tumor causes a headache that typically is worse when the person first awakens. If headaches with these characteristics start in a person who has not had headaches before, a brain tumor may be the cause.
Brain tumors may produce a change in personality. For example, a person may become withdrawn, moody, and, often, inefficient at work. A person may feel drowsy, confused, and unable to think. Such symptoms are often more apparent to family members and co-workers than to the person. Depression and anxiety, especially if either develops suddenly, may be an early symptom of a brain tumor. Bizarre behavior is unusual. In older people, certain brain tumors cause symptoms that may be mistaken for those of dementia.
Other common symptoms of a brain tumor include dizziness, loss of balance, and incoordination. Later, as the pressure within the skull increases, nausea, vomiting, lethargy, drowsiness, intermittent fever, and even coma may occur. Some brain tumors cause seizures.
Depending on which area of the brain is affected, a tumor can cause an arm, a leg, or one side of the body to become weak or paralyzed or can impair the ability to feel heat, cold, pressure, a light touch, or sharp objects. The ability to express or understand language may be lost. Tumors can also affect hearing, smell, and sight (causing such symptoms as double vision and loss of vision). For example, a pituitary tumor may press on the nearby optic nerves (cranial nerve II), which are involved in vision, and thus impair peripheral vision. If the tumor compresses the brain stem, the pulse and breathing rate may become abnormally fast or slow. Any of these symptoms suggests a serious disorder and requires immediate medical attention.
If a tumor blocks the flow of cerebrospinal fluid through the spaces within the brain (ventricles) , fluid may accumulate, causing the ventricles to enlarge (a condition called hydrocephalus) . As a result, pressure within the skull increases. In addition to other symptoms of increased pressure, hydrocephalus causes difficulty turning the eyes upward. In infants, the
head enlarges.
If the pressure within the skull is greatly increased, the brain may be pushed downward because the skull cannot expand. Herniation of the brain (brain under pressure) may result. There are two main types. In a transtentorial herniation, the upper part of the brain (cerebrum) is forced through the narrow opening (the tentorial notch) in the relatively rigid tissue that separates the cerebrum from the lower parts of the brain (cerebellum and brain stem). In people with this type of herniation, consciousness is reduced. The side of the body opposite the tumor may be paralyzed.
In a tonsillar herniation, a tumor that originates in the lower part of the brain pushes the lowest part of the cerebellum (the cerebellar tonsils) through the opening at the base of the skull (the foramen magnum). As a result, the brain stem, which controls breathing, heart rate, and blood
pressure, is compressed and malfunctions. If not diagnosed and treated immediately, a tonsillar herniation rapidly results in coma and death.

Common Symptoms of Some Brain Tumors Astrocytomas and Oligodendrogliomas
Some astrocytomas and oligodendrogliomas grow slowly and may initially cause only seizures. Others (anaplastic astrocytomas and anaplastic oligodendrogliomas) grow fast and are cancerous; they can produce various symptoms of brain dysfunction. Glioblastoma multiforme, a type of astrocytoma, grows so fast that it increases pressure in the brain, causing headaches and slowed thinking. If the pressure becomes high enough, drowsiness, then coma may result.
Symptoms vary depending on the tumor's location. Tumors in the frontal lobes (located behind the forehead) can cause weakness and personality changes. If they develop in the dominant frontal lobe (the left lobe in most people and the right lobe in some lefthanders) , they can cause speech disturbances.
Tumors in the parietal lobes (located behind the frontal lobes) can cause loss of or changes in sensation; sometimes vision is lost in the eye on the side opposite the tumor. Tumors in the temporal lobes (located above the ears) can cause seizures and, if they develop on the dominant side, the inability to understand and use language. Tumors in the occipital lobes (toward the back of the head) can cause partial loss of vision in both eyes.
Tumors of or near the cerebellum (above the back of the neck), especially medulloblastomas in children, can cause alterations in eye movements, incoordination, unsteadiness in walking, and sometimes hearing loss and dizziness. They can block the drainage of cerebrospinal fluid, causing fluid to accumulate in the spaces within the brain (ventricles) . As a result, the ventricles enlarge (a condition called hydrocephalus) , and pressure within the skull increases. Symptoms include headaches, nausea, vomiting, difficulty turning the eyes upward, lethargy, and coma with herniation of the brain. In infants, the head enlarges.

Meningiomas
Meningiomas are usually noncancerous but may recur after they are removed. They occur more often in women and usually appear in people aged 40 to 60, but they can begin growing in childhood or later life. They may cause weakness or numbness, seizures, an impaired sense of smell, and changes in vision. If they become very large, they may cause mental deterioration, including memory loss, much like dementia.

Pineal Tumors
Pineal tumors usually develop during childhood and often cause early puberty. They can obstruct the drainage of cerebrospinal fluid around the brain, leading to hydrocephalus. The most common type of pineal tumor is a germ cell tumor.

Pituitary Gland Tumors
The pituitary gland, located at the base of the skull, controls much of the body's endocrine system. Tumors of the pituitary gland (pituitary adenomas) are usually noncancerous. They secrete abnormally large amounts of pituitary hormones. Effects vary depending on which hormone is secreted in large amounts.
For growth hormone, extreme height (gigantism) or disproportionate enlargement of the head, face, hands, feet, and chest (acromegaly) For corticotropin, Cushing's syndrome For thyroid-stimulating hormone (TSH), hyperthyroidism For prolactin, the cessation of menstrual periods (amenorrhea) in women, production of breast milk in women who are not breastfeeding (galactorrhea), and, in men, erectile dysfunction and enlargement of the breasts (gynecomastia)
Pituitary gland tumors can also destroy the tissues in the pituitary gland that secrete hormones, eventually resulting in insufficient levels of these hormones in the body. Headaches commonly occur. If the tumor enlarges, peripheral vision in both eyes is lost.

What Is Pseudotumor Cerebri?
In pseudotumor cerebri (also called benign intracranial hypertension) , the pressure within the skull (intracranial pressure) increases without any evidence of a cause, such as a tumor, an infection, or a blockage that prevents the cerebrospinal fluid around the brain from draining. It is most common among women aged 20 to 50, especially those who are overweight.
In most people, neither the development nor the eventual disappearance of pseudotumor cerebri can be traced to a particular event. In about one third of people, the cause is blockage of the large veins (venous sinuses) that carry blood from the brain. In children, pseudotumor cerebri sometimes develops after corticosteroids are withdrawn or after a child has taken excessive amounts of vitamin A or the antibiotic tetracycline.
Pseudotumor cerebri usually begins with a headache, which is often mild at first but becomes severe. Late in the course of the disorder, about 5% of people lose their vision, partially or completely, in one or both eyes. The increased pressure within the skull may cause the optic nerve to swell near the eyeball-a condition called papilledema. Doctors can observe the swelling by looking at the back of the eye through an ophthalmoscope.
When evaluating people with pseudotumor cerebri, doctors first rule out any possible treatable cause of the increased pressure within the skull. The results of computed tomography (CT) are usually normal, but spaces within the brain may appear slightly compressed. A spinal tap (lumbar puncture) is performed to measure pressure of the cerebrospinal fluid, which is usually increased, and to analyze the fluid, which is usually normal in content. Pseudotumor cerebri often disappears without treatment within 6 months. Nonetheless, overweight people should lose weight. Aspirin or paracetamol may relieve the headache. If the increased intracranial pressure is not relieved within a few weeks, doctors may prescribe the drug acetazolamide to help reduce the pressure.
Pseudotumor cerebri recurs in about 10% of people. It becomes chronic and progressively worse in some people, eventually causing blindness. Once vision is lost, it may never return, even if the pressure around the brain is relieved. However, vision need not be lost. People with the chronic form of the disorder should check their vision daily by reading small print and immediately report any changes in vision to their doctor or go to the emergency department. If vision is threatened, several procedures can reduce intracranial pressure.
Spinal taps can be performed daily or weekly to remove cerebrospinal fluid. Or, surgery on the optic nerve sheath (fenestration) may be performed. In this procedure, slits or patches are cut in the covering of the optic nerve behind the eyeball, allowing cerebrospinal fluid to escape into the tissues around the eye, where the fluid passes into veins. If the disorder persists, a permanent drain (shunt) can be surgically placed so that excess fluid can be removed.

Diagnosis
Doctors consider the possibility of a brain tumor in people who have had a seizure for the first time or who have the characteristic symptoms. Although doctors can often detect brain dysfunction by performing a physical examination, other procedures are needed to diagnose a brain tumor.
Standard x-rays of the skull can detect tumors that erode bone (such as a meningioma or pituitary adenoma). However, magnetic resonance imaging (MRI) and computed tomography (CT) are more useful because they can detect all types of brain tumors. They can also show the tumor's size and exact position in great detail. When a brain tumor is detected, more diagnostic
procedures are performed to determine the particular kind.
Sometimes a spinal tap (lumbar puncture) is performed to obtain cerebrospinal fluid for examination under a microscope. This procedure is performed when doctors suspect that the tumor has invaded the meninges, is compressing the cranial nerves, and is blocking the flow of cerebrospinal fluid. The procedure may also help when the diagnosis or the type of tumor is unclear. Cerebrospinal fluid may contain cancer cells. However, a spinal tap cannot be performed in people who have a large tumor that is increasing pressure within the skull. The removal of cerebrospinal fluid during a spinal tap may cause the tumor to move, resulting in herniation of the brain.
A biopsy of the tumor (removal of a sample of the tumor for examination under a microscope) is usually needed to identify the type of tumor, including whether it is cancerous. A biopsy may be performed during surgery in which all or part of the tumor is removed. If a tumor is difficult to
reach, a biopsy may be performed using three-dimensional needle placement (stereotactic biopsy) with CT.

Treatment and Prognosis
Treatment of a brain tumor depends on its location and type. When possible, the tumor is removed surgically. Some brain tumors can be removed with little or no damage to the brain. However, many grow in an area that makes removal difficult or impossible without destroying essential structures.
Surgery sometimes causes brain damage that can lead to partial paralysis, changes in sensation, weakness, and impaired intellect. Nevertheless, removing a tumor-whether cancerous or noncancerous- is essential if its growth threatens important brain structures. Even when a cure is impossible, surgery may be useful to reduce the tumor's size, relieve symptoms, and help
doctors determine whether other treatments, such as radiation therapy or chemotherapy, are warranted.
Removal of noncancerous tumors is often safe and cures the person. However, very small tumors and tumors in older people may be left in place as long as they are not causing symptoms. Sometimes radiation therapy is given after surgery to destroy any remaining tumor cells. Radiosurgery is used to treat tumors that are small and not readily accessible with traditional surgery.
It is also used to treat meningiomas. Radiosurgery uses focused radiation to destroy a tumor rather than an incision to remove it. With radiosurgery, treatment is completed in 1 day.
Most cancerous brain tumors are treated with a combination of surgery, radiation therapy, and chemotherapy. As much of the tumor as can be removed safely is removed, and then radiation therapy is begun. Radiation therapy is given over a course of several weeks. It rarely cures but may shrink a tumor enough to keep it under control for many months or even years. Chemotherapy is used to treat some types of cancerous brain tumors. Chemotherapy appears
to be particularly effective in treating anaplastic oligodendrogliomas.
Radiosurgery is also used to treat cancerous brain tumors. Increased pressure within the skull is extremely serious and requires immediate medical attention. Drugs such as mannitol and corticosteroids are usually given by injection to reduce the pressure and prevent herniation.
Corticosteroids can often restore function within days, even if the tumor is large. If the tumor is blocking the flow of cerebrospinal fluid through the spaces within the brain, a device may be used to reduce the risk of herniation by draining the cerebrospinal fluid. The device consists of a
small tube (catheter) connected to a gauge that measures the pressure within the skull. The tube is inserted through a tiny opening drilled in the skull.
This procedure may be performed using a local anesthetic (usually plus a sedative) or a general anesthetic. The tube is removed or converted to a permanent drain (shunt) after a few days. During this time, doctors surgically remove all or part of the tumor or use radiosurgery or radiation therapy to reduce the size of the tumor and thus relieve the blockage.
Treatment of metastases to the brain depends largely on where the cancer originated. Radiation therapy directed at the metastases in the brain is often performed. Surgical removal may benefit people who have only a single metastasis. In addition to traditional treatments, radiosurgery and some experimental treatments, involving chemotherapy and radioactive implants in the tumor, are being tried.
The prognosis for people who have a brain tumor ranges from complete recovery to death, depending on the type and location of the tumor.

End-of-Life Issues: Because people with cancerous brain tumors have a limited life expectancy, establishing advance directives is advisable.
Advance directives can help a doctor determine what kind of care people want if they become unable to make decisions about medical care. Many cancer centers, especially those with hospice facilities, provide counseling and home health services.

Understanding Tumor Treatment Craniotomy:
After part of the scalp is shaved, an incision is made through the skin. A high-speed drill and a special saw are used to remove a small piece of bone above the tumor. The tumor is located and removed. Usually, the bone is then replaced and the incision stitched closed. A scalpel may be used to cut out the tumor; a laser (using heat) may be used to vaporize the tumor; or a device that emits ultrasound waves may be used to break the tumor apart, so that the pieces can be suctioned out (aspirated). Lasers and ultrasound devices are used to remove tumors that would be difficult to cut out.

Stereotactic techniques:
Computers are used to produce a three-dimensional image of the tumor and thus to precisely locate a tumor and determine its relationship to other structures in the brain. The three-dimensional image can be obtained by attaching a metal imaging frame with a series of rods to the person's skull.
The rods appear as dots on a CT scan, providing reference points, which help locate the tumor. Other devices, such as a viewing wand or compass system, do not involve attaching a frame and may be used instead. Stereotactic techniques can be used to biopsy or remove tumors or to insert implants containing a chemotherapy drug or radioactive pellets.

Radiosurgery:
Radiosurgery is not really surgery because no incision is required. Focused radiation is used to destroy a tumor. Because the radiation is focused, a smaller dose can be used. Several machines, including a gamma knife and a linear accelerator, can produce this type of radiation.
When a gamma knife is used, an imaging frame is attached to the person's skull. The person lies on a sliding bed, and a large helmet with holes in it is placed over the frame. The head of the bed is then slid into a globe that contains radioactive cobalt. Radiation passes through the holes in the helmet and is aimed precisely at the tumor.
A linear accelerator circles the head of the person, who lies on a sliding bed. The linear accelerator aims radiation precisely at the tumor.

Implants:
After a tumor is removed and before the skull and incision are closed, wafers soaked with a chemotherapy drug may be placed in the space where the tumor was. As the wafers gradually dissolve, they release the drug to destroy any remaining cancer cells.
A thin tube called a catheter may be inserted through an incision and used to place radioactive implants directly into the tumor. The implants may be removed after a few days or months or may be left in place. Unlike people who have externally applied radiation therapy, people who have radioactive implants are radioactive for a time and need to take precautions as advised
by their doctor. After this procedure, surgery may be necessary to remove dead cancer cells.

Shunts:
If a tumor causes pressure within the skull to increase, a shunt may be surgically placed. A shunt is a thin piece of tubing that is inserted into one of the spaces of the brain (ventricles) or sometimes into the space around the spine that contains cerebrospinal fluid (subarachnoid space). The other end of the tubing is threaded under the skin from the head usually to
the abdominal cavity. Excess cerebrospinal fluid is drained from the brain and is absorbed in the abdominal cavity. The shunt contains a one-way valve that opens when there is too much fluid in the brain. Shunts may be temporary (until the tumor is removed) or permanent. (Merck)