Symptoms & Diagnosis of Brain Tumors
The symptoms of brain tumors depend on their size and location in the brain. Symptoms often are caused by damage to vital tissue and pressure on the brain as the tumor grows within the limited space in the skull. They may be caused by swelling and a buildup of fluid around the tumor, a condition called edema. Symptoms also may be due to hydrocephalus, which occurs when the tumor blocks the flow of cerebrospinal fluid and causes a build-up in the ventricles. If a brain tumor grows very slowly, its symptoms may not appear for some time.
The most frequent symptoms of brain tumors include:
1.) Headaches that tend to be worse in the morning and ease during the day
2.) Seizures or convulsions
3.) Nausea or vomiting
4.) Weakness or loss of feeling in the arms or legs
5.) Stumbling or lack of coordination in walking
6.) Abnormal eye movements or changes in vision
8.) Changes in personality or memory
9.) Changes in speech
These symptoms may be caused by brain tumors or by other problems. Diagnostic tests can be performed to determine if the cause of your symptoms is a brain tumor and if it is a primary or secondary one.
How is brain tumor diagnosed?
Identifying a brain tumor usually involves a neurological examination, brain scans, and/or an analysis of the brain tissue. Doctors use the diagnostic information to classify the tumor from the least aggressive (benign) to the most aggressive (malignant). In most cases, a brain tumor is named for the cell type of origin or its location in the brain. Identifying the type of tumor helps doctors determine the most appropriate course of treatment. A neurological examination is a series of tests to measure the function of the patient’s nervous system and physical and mental alertness. If responses to the exam are not normal, the doctor may order a brain scan or refer the patient to a neurologist or neurosurgeon, who will then order a brain scan. A brain scan is a picture of the internal structures in the brain.
A specialized machine takes a scan in much the same way a digital camera takes a photograph. Using computer technology, a scan compiles an image of the brain by photographing it from various angles. Some types of scans use a contrast agent (or contrast dye), which helps the doctor see the difference between normal and abnormal brain tissue. The contrast agent is injected into a vein and flows into brain tissue. Abnormal or diseased brain tissue absorbs more dye than normal healthy tissue. The most common scans used for diagnosis are as follows: MRI (Magnetic Resonance Imaging) is a scanning device that uses magnetic fields and computers to capture images of the brain on film. It does not use x-rays. It provides pictures from various planes, which permit doctors to create a three-dimensional image of the tumor.
The MRI detects signals emitted from normal and abnormal tissue, providing clear images of most tumors. CT or CAT Scan (Computed Tomography) combines sophisticated x-ray and computer technology. CT can show a combination of soft tissue, bone, and blood vessels. CT images can determine some types of tumors, as well as help detect swelling, bleeding, and bone and tissue calcification. Usually, iodine is the contrast agent used during a CT scan. PET Scan (Positron Emission Tomography) provides a picture of the brain s activity, rather than its structure, by measuring the rate at which a tumor absorbs glucose (a sugar). The patient is injected with deoxyglucose that has been labeled with radioactive markers. The PET scan measures the brain s activity and sends this information to a computer, which creates a live image. Doctors use PET scans to see the difference between scar tissue, recurring tumor cells, and necrosis (cells destroyed by radiation treatment).
A biopsy is a surgical procedure in which a sample of tissue is taken from the tumor site and examined under a microscope. The biopsy will provide information on types of abnormal cells present in the tumor. The purpose of a biopsy is to discover the type and grade of a tumor. A biopsy is the most accurate method of obtaining a diagnosis. An open biopsy is done during a craniotomy. A craniotomy involves removing a piece of the skull in order to get access to the brain. After the tumor is resected (completely removed) or debulked (partially removed), the bone is usually put back into place. A closed biopsy (also called a stereotactic or needle biopsy) may be performed when the tumor is in an area of the brain that is difficult to reach. In a closed biopsy, the neurosurgeon drills a small hole into the skull and passes a narrow hollow needle into the tumor to remove a sample of tissue.
Once a sample is obtained, a pathologist examines the tissue under a microscope and writes a pathology report containing an analysis of the brain tissue. Sometimes the pathologist may not be able to make an exact diagnosis. This may be because more than one grade of tumor cells exists within the same tumor. In some cases, the tissue may be sent to another institution for additional analysis.