Some Specific Brain Tumors
Types of brain tumors (see also table Some Tumors That Originate in or near the Brain) can vary in their characteristics, such as their location, the people they affect most often, and the symptoms they cause.
Gliomas include astrocytomas, oligodendrogliomas, and ependymomas. Astrocytomas are the most common glioma.
Some astrocytomas and oligodendrogliomas grow slowly and may initially cause only seizures. Others, such as anaplastic astrocytomas and anaplastic oligodendrogliomas, grow fast and are cancerous. (Anaplastic means that a cell has not become specialized to do a specific function—that is, the cell is undifferentiated, Undifferentiated cells in a tumor suggest that the tumor is rapidly growing.) Astrocytomas tend to develop in young people. They can become more aggressive and are then called glioblastomas. Glioblastomas tend to develop during middle or old age. Glioblastomas may grow so fast that they increase pressure in the brain, causing headaches and slowed thinking. If the pressure becomes high enough, drowsiness, then coma, may result.
Ependymomas develop from cells that line the spaces within the brain (ventricles). Ependymomas, which are uncommon, develop mainly in children.
Symptoms of gliomas vary depending on the tumor’s location.
Frontal lobes (located behind the forehead): Tumors located here can cause seizures, problems with walking, a compelling need to urinate, involuntary loss of urine (urinary incontinence), and paralysis. People may not be able to pay attention or think clearly. They may become lethargic. If tumors develop in the dominant frontal lobe (the left lobe in most people and the right lobe in some left-handers), they can cause problems with language. People may struggle to express themselves even though they know what they want to say.
Parietal lobes (located behind the frontal lobes): Tumors located here can cause loss of position sense (knowing where parts of the body are in space) and changes in sensation. People may be unable to tell whether they are being touched in one or two places. Sometimes vision is partially lost in both eyes so that neither eye can see the side of the body opposite the tumor. People may have seizures.
Temporal lobes (located above the ears at the temples): Tumors located here can cause seizures, and if they develop on the dominant side, people may be unable to understand and use language. Vision may be partially lost in both eyes so that neither eye can see the side opposite the tumor.
Occipital lobes (toward the back of the head, above the cerebellum): Tumors located here can cause partial loss of vision in both eyes, visual hallucinations (seeing things that are not there), and seizures.
In or near the cerebellum (located at the back of the head just above the neck): Tumors located here can cause nystagmus (rapid movement of the eyes in one direction, then a slower drift back to the original position), incoordination, unsteadiness in walking, and sometimes hearing loss and vertigo. 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, problems with vision (such as double vision), and lethargy. In infants, the head enlarges. Greatly increased pressure can cause herniation of the brain, which can result in coma and death.
Medulloblastomas develop mainly in children and young adults. They develop in the cerebellum (located at the back of the head just above the neck). Thus, they may block the drainage of cerebrospinal fluid from the spaces within the brain (ventricles). Thus, fluid may accumulate in the ventricles, causing them to enlarge (called hydrocephalus). As a result, pressure on the brain increases. These tumors also cause nystagmus (rapid movement of the eyes in one direction, then a slower drift back to the original position), loss of coordination, and unsteadiness in walking.
Medulloblastomas may spread through the cerebrospinal fluid (the fluid that surrounds the brain and spinal cord), above to the cerebrum and below to the spinal cord.
Meningiomas are among the most common brain tumors. They are usually noncancerous but may recur after they are removed.
Meningiomas are the only brain tumor that is more common among women. They usually appear in people aged 40 to 60, but they can begin growing during childhood or later life. These tumors do not directly invade the brain but may compress the brain or cranial nerves, block the absorption of cerebrospinal fluid, or do both.
Symptoms depend on where the tumor develops. They may include weakness or numbness, seizures, an impaired sense of smell, changes in vision, and impaired mental function. In older people, a meningioma may cause dementia.
Tumors can develop near the pineal gland, a small structure deep within the brain. Pineal tumors usually develop during childhood and often cause early puberty, especially in boys. They can block the drainage of cerebrospinal fluid around the brain, leading to hydrocephalus (accumulation of fluid in the brain's ventricles, causing them to enlarge). As a result, pressure on the brain increases.
The most common type of pineal tumor is a germ cell tumor.
Symptoms of pineal tumors include the inability to look up and drooping eyelids. The eyes may be unable to adjust to changes in light.
The pituitary gland, located at the base of the brain, controls much of the body’s endocrine (hormone) system. Most tumors of the pituitary gland are pituitary adenomas, which are usually noncancerous. Pituitary adenomas tumors may secrete abnormally large amounts of pituitary hormones or block production of hormones. When large amounts of hormones are secreted, effects vary depending on which hormone is involved.
Pituitary gland tumors can block hormone production by destroying the tissues in the pituitary gland that secrete hormones, eventually resulting in insufficient levels of these hormones in the body.
Headaches commonly occur. Rarely, bleeding into the tumor occurs, causing a sudden headache and loss of vision.