What Is a Brain Tumor?
A brain tumor is a collection (or mass) of abnormal cells in the brain. The skull is very rigid and the brain is enclosed, so any growth inside such a restricted space can cause problems. Brain tumors can be cancerous (malignant) or non-cancerous (benign). When benign or malignant tumors grow they can cause the pressure inside the skull to increase. This can cause brain damage and even death.
Brain tumors are categorized as primary or secondary. Primary brain tumors originate in the brain. According to the University of Maryland Medical Center, about half of primary brain tumors are benign. Secondary brain tumors occur when cancer cells spread to the brain from another organ such as the lung or breast.
Primary brain tumors originate in the brain. They can develop from brain cells, the membranes that surround the brain (meninges), nerve cells, or glands. In adults, the most common types of brain tumors are gliomas and meningiomas. Primary tumors can be benign or cancerous.
Gliomas are tumors that develop from glial cells. These cells support the structure of the central nervous system, provide nutrition, clean cellular waste, and break down dead neurons. Gliomas develop from a variety of glial cells, including astroglia (astrocyte), microglia, oligodendroglia, satellite cells, and schwann cells.
Types of tumors that begin in glial cells are:
- astrocytic tumors such as astrocytomas (can be noncancerous)
- oligodendroglial tumors
- glioblastomas (most aggressive)
- meningiomas (originate in the meninges) and Schwannomas (orginate in schwann cells)
Most meningiomas and schwannomas occur in patients between the ages of 40 and 70. Meningiomas are more common in women, while schwannomas occur equally in both sexes. These tumors are usually benign but can cause death because of their size and location. Cancerous meningiomas and schwannomas can be very aggressive.
Other primary brain tumors are:
- pituitary tumors (most pituitary tumors are benign)
- pineal gland tumors (can be benign or malignant)
- ependymomas (most are benign)
- craniopharyngiomas (occur mostly in children; they are microscopically benign but can have clinical symptoms such as changes in vision and premature puberty)
- primary brain lymphomas (malignant)
- primary CNS lymphomas (malignant)
- primary germ cell tumors of the brain (can be benign or malignant)
Secondary brain tumors make up the majority of brain cancers. They start in one part of the body and spread, or metastasize, to the brain. Cancers of the lung, breast, kidney, or skin can metastasize to the brain. Secondary (metastatic) brain tumors are always malignant. Benign tumors do not spread from one part of the body to another.
Risk factors for brain tumor include:
A small percentage of people with brain tumors have family members who also have brain tumors.
Risk for brain tumors increases with age. Medulloblastomas occur mostly in children.
Brain tumors are most likely to occur in whites. African-Americans are more likely to get meningiomas than whites.
Exposure to certain on the job chemicals can increase risk for brain cancer.
Exposure to Radiation
People with exposure to ionizing radiation have increased risk of brain tumors. Radiation used for cancer treatments and fallout from atomic bombs are both examples of ionizing radiation.
History of Chicken Pox
According to the American Brain Tumor Association, people with a history of childhood chicken pox have a decreased risk of getting brain tumors.
Symptoms of brain tumors depend upon the location and size of the tumor. Tumors cause direct damage by invading brain tissue and causing brain pressure to increase. Compression of brain tissue by a growing tumor creates noticeable symptoms.
Some of the most common symptoms include:
- may be worse in the morning when waking up
- can occur during sleep
- are aggravated by coughing, sneezing or exercise
- can be associated with vomiting, blurred vision, double vision, or confusion
- seizures (especially in adults)
- weakness of a limb or part of the face
- change in mental functioning
- memory loss
- difficulty writing or reading
- changes in the ability to hear taste or smell
- decreased alertness (may include drowsiness and loss of consciousness)
- difficulty swallowing
- dizziness or vertigo
- eye problems such as drooping eyelids and unequal pupils
- uncontrollable movements
- hand tremors
- loss of balance
- loss of bladder or bowel control
- numbness or tingling on one side of the body
- trouble speaking or understanding what others are saying
- changes in mood, personality, emotions, and behavior
- difficulty walking
- muscle weakness in the face, arm, or leg
Symptoms of Pituitary Tumors
The following symptoms can occur with pituitary tumors:
- nipple discharge (galactorrhea)
- lack of menstruation in women
- development of breast tissue (gynecomastia) in men
- enlargement of the hands and feet
- sensitivity to heat or cold
- increased amounts of body hair (hirsutism)
- low blood pressure
Diagnosis of a brain tumor begins with a physical exam and a look at the patient’s medical history. The physical exam includes a very detailed neurological examination. During this exam, the doctor tests to see if your cranial nerves (nerves that have their origin in the brain) are intact. The doctor also evaluates your muscle strength and coordination. This examination includes looking inside the eyes with an ophthalmoscope, an instrument that shines a light through your pupils and onto your retinas. This allows the doctor to check how your pupils react to light. It also allows the doctor to look directly into your eyes to see if there is any swelling of the optic nerve. When pressure increases inside the skull, changes in the optic nerve can occur. The doctor may also test your memory and check your ability to do mathematical calculations.
Tests are ordered based on the findings of the history and physical. The University of Pittsburgh Department of Neurosurgery and the Mayo Clinic say that the following tests are useful for diagnosis of brain tumor:
CT Scan of the Head (With or Without Contrast)
Contrast is achieved in a CT (computerized tomography) scan of the head by using a special dye that helps doctors see some structures more clearly.
MRI of the Head
With an MRI of the head, a special dye can be used to help doctors detect tumors.
This study uses a dye that is injected into an artery (usually in the groin area). The dye travels to the arteries in the brain, allowing doctors to see what the blood supply of tumors look like. This information is useful at the time of surgery.
A brain scan uses harmless radioactive dye that is injected into a vein. The dye is taken up by the tumor and the images of the uptake are captured on film.
Brain tumors can cause changes in the bones of the skull, and specific X-rays can show if any changes have occurred. These X-rays can also pick up calcium deposits, which are sometimes contained within a tumor.
A small piece of the tumor is obtained and examined by a specialist called a neuropathologist. The biopsy will identify if the tumor cells are benign or malignant. It will also determine whether the cancer originated in the brain (primary) or another part of the body (secondary).
Treatment of brain tumors depends on type, size, location, and the person’s general health.
The most common treatment for malignant brain tumors is surgery. The goal is to remove all traces of cancer without causing damage to the healthy parts of the brain. While the location of some tumors allow for easy and safe removal, other tumors may be located in an area that limits how much of the tumor can be removed. Even partial removal of brain cancer can be beneficial to the patient. Risks of brain surgery include infection and bleeding. Clinically dangerous benign tumors are also surgically removed. Metastatic brain tumors are treated according to guidelines for the type of original cancer.
Surgery can be combined with other treatments such as radiation therapy and chemotherapy.
Physical therapy, occupational therapy, and speech therapy can help people to recover after neurosurgery.