عدد الرسائل : 4030
العمر : 29
العمل/الترفيه : المدير
السٌّمعَة : 4
نقاط : 982
تاريخ التسجيل : 02/04/2008
|موضوع: brain tumors الثلاثاء 08 أبريل 2008, 19:07|| |
As a brain tumor grows, it can increase pressure inside the skull. Brain tissue surrounding the tumor may become inflamed and swell, further increasing pressure. The tumor can also distort delicate brain structure.
Glioblastoma multiforme - adults; Ependymoma - adults; Glioma - adults; Astrocytoma - adults; Medulloblastoma - adults; Neuroglioma - adults; Oligodendroglioma - adults; Meningioma - adults; Cancer - brain tumor (adults)
Causes, incidence, and risk factors
Primary brain tumors include any tumor that starts in the brain. Tumors may be confined to a small area, invasive (spread to nearby areas), benign (not cancerous), or malignant (cancerous).
Tumors can directly destroy brain cells. They can also indirectly damage cells by producing inflammation, compressing other parts of the brain as the tumor grows, causing swelling in the brain, and increasing pressure within the skull.
Brain tumors are classified depending on the exact site of the tumor, the type of tissue involved, benign or malignant tendencies of the tumor, and other factors. Primary brain tumors can arise from the brain cells, the meninges (membranes around the brain), nerves, or glands.
The cause of primary brain tumors is unknown. This is because they are rare, there are many types, and there are many possible risk factors that could play a role. Exposure to some types of radiation, head injuries, and hormone replacement therapy may be risk factors, as well as many others. The risk of using cell phones is hotly debated.
Some inherited conditions increase the risk of brain tumors, including neurofibromatosis, Von Hippel-Lindau syndrome, Li-Fraumeni syndrome, and Turcot's syndrome.
Tumors may occur at any age, but many specific tumors have a particular age group in which they are most common. In adults, gliomas and meningiomas are most common.
SPECIFIC TUMOR TYPES
Gliomas are thought to be derived from glial cells such as astrocytes, oligodendrocytes, and ependymal cells. The gliomas are subdivided into 3 types:
• Astrocytic tumors include astrocytomas (less malignant), anaplastic astrocytomas, and glioblastomas (most malignant). Astrocytomas can progress over time more malignant forms, including glioblastoma.
• Oligodendroglial tumors also can vary from low grade to very malignant. Some primary brain tumors are composed of both astrocytic and oligodendrocytic tumors. These are called mixed gliomas.
• Glioblastomas are the most aggressive type of primary brain tumor. These may or may not arise from a prior lower grade primary brain tumor.
Meningiomas are another type of brain tumor. These tumors:
• Occur most commonly between the ages of 40-70
• Much more common in women.
• While 90% are benign, they still may cause devastating complications and death due to their size or location. Some are cancerous and aggressive.
Other primary brain tumors in adults are rare and include ependymomas, craniopharyngiomas, pituitary tumors, pineal gland tumors, and primary germ cell tumors of the brain.
The specific symptoms depend on the tumor's size, location, degree of invasion, and related swelling. Headaches, seizures, weakness in one part of the body, and changes in the person's mental functions are most common.
Symptoms may include:
• Headache -- a persistent headache that is new for the person, worse on awakening
• Vomiting -- possibly accompanied by nausea; more severe in the morning
• Personality and behavior changes
• Emotional instability, rapid emotional changes
• Loss of memory, impaired judgment
• Seizures that are new for the person
• Reduced alertness
• Double vision, decreased vision
• Hearing loss
• Decreased sensation of a body area
• Weakness of a body area
• Speech difficulties
• Decreased coordination, clumsiness, falls
• Fever (sometimes)
• Weakness, lethargy
• General ill feeling
• Positive Babinski's reflex
• Decerebrate posture
• Decorticate posture
Additional symptoms that may be associated with primary brain tumors:
• Tongue problems
• Swallowing difficulty
• Impaired sense of smell
• Uncontrollable movement
• Dysfunctional movement
• Absent menstruation
• Hand tremor
• Facial paralysis
• Eye abnormalities
o pupils different sizes
o uncontrollable movements
o eyelid drooping
• Breathing, absent temporarily
• Unusual or strange behavior
Signs and tests
A doctor can often identify signs and symptoms that are specific to the location of the tumor. Some tumors may not show symptoms until they are very large and cause a rapid decline in the person's mental functions. Other tumors have symptoms that develop slowly.
Most brain tumors increase pressure within the skull and compress brain tissue because of their size and weight.
The following tests may confirm the presence of a brain tumor and identify its location:
• CT scan of the head
• MRI of the head
• Examination of tissue removed from the tumor during surgery or CT-guided biopsy (may confirm the exact type of tumor)
• Examination of the cerebral spinal fluid (CSF) may reveal cancerous cells
Treatment can involve surgery, radiation therapy, and chemotherapy. Brain tumors are best treated by a team involving a neurosurgeon, radiation oncologist, oncologist or neuro-oncologist, and other health care providers, such as neurologists and social workers.
Early treatment often improves the chance of a good outcome. Treatment, however, depends on the size and type of tumor and the general health of the patient. The goals of treatment may be to cure the tumor, relieve symptoms, and improve brain function or the person's comfort.
Surgery is necessary for most primary brain tumors. Some tumors may be completely removed. Those that are deep inside the brain or that enter brain tissue may be debulked instead of entirely removed. Debulking is a procedure to reduce the tumor's size.
Tumors can be difficult to remove completely by surgery alone, because the tumor invades surrounding brain tissue much like roots from a plant spread through soil. In cases where the tumor cannot be removed, surgery may still help reduce pressure and relieve symptoms.
Radiation therapy and chemotherapy may be used for certain tumors.
Other medications used to treat primary brain tumors in children may include:
• Corticosteroids such as dexamethasone to reduce brain swelling
• Osmotic diuretics such as urea or mannitol to reduce brain swelling and pressure
• Anti-convulsants such as phenytoin to reduce seizures
• Pain medications
• Antacids or histamine blockers to control stress ulcers