The most common symptoms include headaches, which can be most severe in the morning; nausea or vomiting, which can be most severe in the morning; seizures or convulsions; difficulty thinking, speaking, or finding words; personality changes; weakness or paralysis in one part or one side of the body; loss of balance; vision changes; confusion and disorientation; and memory loss. Different parts of the brain control different functions, so symptoms will vary depending on the tumor's location.

A brain tumor diagnosis usually involves several steps, which can include a neurological examination, brain scan(s) and/or a biopsy.

A neurological examination is a series of tests to measure the function of the patients nervous system and physical and mental alertness. If responses to the exam are not normal, the doctor may order a scan or refer the patient to a neurologist or neurosurgeon, who will then order a 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 to 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.

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 permits 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. People who are allergic to iodine should inform their doctor before having a CT scan.

CT is a valuable diagnostic tool and its use has been increasing rapidly. However, CT scans involve exposure to ionizing radiation, which is known to cause cancer. This is a concern for people who have multiple CT scans and for children, because they are more sensitive to radiation than adults. It is wise for people who have had frequent x-ray exams and parents of children who have brain tumors to keep a record of their x-ray history. This information can help doctors make informed decisions and minimize radiation over-exposure.

PET Scan (Positron Emission Tomography) provides a picture of the brains 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 brains 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).

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 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.

For more information about brain tumor diagnosis, see chapter 2 of The Essential Guide to Brain Tumors.

Because an MRI uses magnetic fields, people who have metal implanted in their body in any form should let the doctor know about it before scheduling the procedure. An MRI may not be an option for these patients because the intense magnetic fields can damage some types of implanted medical devices. Patients should advise the doctor if they have a pacemaker, cardiac monitor, surgical clip, or facial tattoos.

In a standard MRI scan, the patient lies on a narrow table, which slides through a long, cylindrical tube with a narrow opening. Although there is enough room for the patient’s body inside the cylinder, the patient will not be able to move around. The scan takes approximately 15-45 minutes. During the scan, the patient will hear loud banging sounds, caused by the electronics within the machine. Patients may request earplugs to reduce noise. Some people find the MRI claustrophobic and ask for a sedative beforehand to relax. Other people request an open MRI.

An open MRI machine does not have a cylinder, so the patient is not enclosed. The procedure lasts approximately 45 minutes. There is some discussion among doctors concerning the quality of the images of an open MRI compared to the standard or closed MRI.

Contrast agents may cause allergic reactions in some patients. Gadolinium, the contrast agent used with an MRI, may cause temporary headaches but has no other known side effects.

Iodine is the contrast agent most commonly used for CT scanning. If you know you are allergic to iodine, tell your doctor. Allergic reactions can include rashes, a warm sensation, or in rare cases, difficulty breathing.

CT scans involve exposure to ionizing radiation, which is known to cause cancer. This is a concern for people who have multiple CT scans and for children, because they are more sensitive to radiation than adults. It is wise for people who have had frequent x-ray exams and parents of children who have brain tumors to keep a record of their x-ray history. This information can help doctors make informed decisions and minimize radiation over-exposure.

For more information about diagnostic tests, see chapter 2 of The Essential Guide to Brain Tumors.

A pathology report contains the analysis of brain tissue taken at the time of a craniotomy or needle biopsy. A pathologist examines the tissue under a microscope. Further tests or analysis may be performed on the tumor tissue. Then the pathologist will write a pathology report, which provides the information to make a diagnosis of the tumor type.

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. If cells of only one grade are removed and classified during a biopsy, it is possible that the tumor grade will be misdiagnosed. This is called a sampling error. In some cases, the tissue may be sent to another institution for additional input.

For more information about diagnostic tests, see chapter 2 of The Essential Guide to Brain Tumors.

The NBTF Interactive Tour of the Brain illustrates parts of the brain and their functions.