What is a brain tumor?
A tumor is an abnormal mass of tissue that grows on or inside the body. It is known as primary if located where its growth first started or secondary if it began growing elsewhere in the body and metastasized, or spread, to its present location. Most primary brain tumors do not metastasize outside the brain.
Inside the skull, tumors can grow almost anywhere: within brain tissue, from the meninges or inside the ventricular system. They can be encapsulated (self-contained) or interwoven with blood vessels, nerves or other brain structures from which they cannot be removed without devastating consequences. Metastatic tumors are usually well localized, may occur alone or in clusters and may spread throughout much of the brain.
A benign tumor usually is encapsulated, does not spread to other areas of the body, grows slowly and often causes problems by compressing brain tissue. A malignant tumor grows uncontrollably, spreads throughout the brain and destroys brain tissue.
What symptoms can it cause?
A brain tumor may at first cause the vague feeling of being "unwell." This may be followed by other, more specific symptoms: dull, persistent headache; nausea or vomiting; generalized weakness; vision problems. Because the left side of the brain governs the right side of the body, and vice versa, a tumor will cause specific weakness or loss of movement on the opposite side of the body. Some symptoms may be caused by the increased pressure inside the skull from brain swelling, which can temporarily be treated with a steroid medication.
Because brain tissue is irritated by the tumor, the brain can temporarily "short-circuit" as its normal electrical activity is interrupted. These periods of uncontrolled brain activity can cause seizures, which may be generalized and cause contractions of all parts of the body, loss of consciousness or bladder and bowel dysfunction. The seizures may instead be of a focal nature, affecting only one arm, a leg or part of the face. Seizures usually can be controlled with anticonvulsant medications.
How is a brain tumor evaluated?
A detailed history-taking of the patient's symptoms and a physical examination are done first, followed by any of several tests, such as X-ray studies, Computerized Tomography (CT) scans and PET scans, Magnetic Resonance Imaging (MRI) and angiograms. All findings are used to evaluate the patient's symptoms, determine the tumor's exact location and provide the physician with a tentative diagnosis of the tumor type.
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Surgical Treatment For Brain Tumors: Craniotomy
What is a craniotomy?
A craniotomy is a surgical procedure for treating brain disorders. The information provided here describes craniotomy for cerebral hemisphere tumors - tumors that occur around or inside the cerebrum. The surgery involves opening the skull to expose the brain, allowing the neurosurgeon access to the affected area of the brain.
Why is surgery necessary?
Surgery makes it possible to diagnose the tumor type by removing a small tissue sample (biopsy) for laboratory testing, which is later studied extensively before a final diagnosis is made. This confirmed diagnosis will make it possible to treat the patient's condition more specifically with radiation or drug therapies.
Intracranial pressure (ICP) rises when a brain tumor grows. The brain also may swell as its tissues are irritated by the tumor. This increase of ICP cannot be released on its own by the body, so surgery may be necessary to find the exact location of the tumor and attempt to remove all or at least part of its mass. Without surgery the brain will be damaged as increasing pressure inside the skull causes compression and, ultimately, death of sensitive brain tissues.
What happens following surgery?
For malignant brain tumors, radiation therapy and/or chemotherapy may be recommended after surgery. A neurosurgeon has the training and expertise to remove all or part of the tumor, if its removal is possible; however, recovery may at times be limited by the extent of damage already caused by the tumor and by the brain's ability to heal. If a neurologic deficit remains, a period of rehabilitation will be necessary to maximize improvement.
Types of Brain Tumors
Growing from abnormal cells of the meninges, (the soft layers between the skull and brain) meningioma is a slow-growing tumor that shares the dura's rich blood supply. It is very often attached to dura and so may be immediately visible when the dura is opened.
A meningioma is usually a benign well-encapsulated tumor. Removal may be complicated by its size, firmness, and attachment to vital blood vessels or brain tissues. A large meningioma or one that is difficult to remove may require a long, tedious surgery. Often the dura removed during tumor surgery may be replaced with other body tissue (fascia) or a dura substitute such as gortex.
Glial cells support the brain's functioning nerve network and are the site of most tumors inside the brain. Gliomas are "graded" according to their degree of malignancy.
Often when the dura is opened, the brain is swollen but otherwise may appear normal. The "center" of the glioma may readily be identified, but because the tumor gradually spreads into surrounding tissue, the boundaries of a glioma are harder to identify.
It may take months for the cells around the edges of the tumor to appear abnormal, yet they can be affected long before they "show" themselves. This is why glioma usually cannot be removed completely, as even one remaining cell can continue the tumor's growth.
Often lying close to the brain's surface, where it irritates the normal tissue around it, a metastatic tumor is one that began in another body organ and traveled in the bloodstream to the brain.
Grown from a "seed" of non-brain tissue (from the breast, kidney or lung, for example) a metastatic tumor often can be separated from the surrounding brain more easily. If only one or two lesions exist, they usually can be surgically removed. Another treatment option is stereotactic radiosurgery or whole-brain radiation.
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