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Brain tumors even haunt the minds of those who will never develop cancer. Headaches, tingling, dizziness and other very common symptoms may set off the fear that a deadly malignancy lurks underneath the everyday façade. How can doctors reassure us, or worse, be confident that a brain tumor is in fact present?
Signs and Symptoms of Brain Tumors
Brain tumors take up space in the skull that should be used by blood, brain, or cerebrospinal fluid (CSF).
Because the skull is a confined space, a tumor often increases intracranial pressure, with telltale signs of headaches that worsen when laying flat or blurred vision. Unfortunately, it’s not always that easy, since some tumors spread more insidiously and do not take up much space at first.
Focal deficits are another indication that something is impacting just one part of the brain, rather than everything at once. Different parts of the brain are responsible for different tasks. For example, the left side of the brain controls the right side of the body. If both sides of the body are weak, the trouble could be with the muscles or the peripheral nerves, but something that has impacted both sides of the brain is less likely. If just half of the body is weak, neurologists worry more about the brain and spinal cord. Similarly, language, personality changes, or other cognitive deficits can indicate a focal brain problem.
To learn more about signs and symptoms of brain tumor, read here: Is it a Brain Tumor?
Diagnostic Tests: Neuroimaging
Different kinds of tumors have different appearances on MRI. Brain metastases, for example, tend to be located close to the edge of the brain, since the metastases spread by the blood stream and the edges of the brain tend to be where the blood vessels are small, where pieces of tumor are more likely to have time to cross the blood brain barrier. Glioblastoma multiforme, in contrast, tends to be a large lesion that spreads across several different areas of brain. Oligodendroglioma may have bright spots due to calcium deposits within the brain. Still, the definitive way to know what type of tumor is present is remove a piece of abnormal tissue and look at it under the microscope, which requires neurosurgery.
Diagnostic Tests: Cerebrospinal Fluid Analysis
In addition to neuroimaging, a lumbar puncture can look for abnormal cells that are floating in the CSF. This can be tricky, however, as there may be only a few free-floating cells, and one CSF collection may not obtain enough cells for identification.
Brain Biopsies
Surgical resection is clearly a delicate matter. The surgeons will rely on neuroimaging to help them know exactly where to cut. Intraoperative monitoring techniques such as electroencephalography and intraoperative MRI can improve surgical outcomes by keeping surgeons away from healthy brain tissue.
Most of the time, surgeons plan for both a biopsy and a resection, meaning they may remove as much of the tumor as they can. While they’re still in the operating room, the surgeons can send a piece of brain to be viewed under a microscope by a pathologist. If the pathologist believes the tissue is cancerous, the surgeons can go on and remove as much of the tumor as possible right then and there. Alternatively, there may be times where the surgeons perform a stereotactic biopsy, where there is no plan to potentially remove the tumor at the same time. This may be the case if the tumor is in a critical location, for example, and extensive surgery would be too dangerous.
The neuropathologists who look at these cells can do more than just say what type of tumor is present. The appearance of the tumor can also allow comments on how aggressive the tumor is. Some stains may be used to determine how sensitive the tumor will likely be to different types of treatments. This information will guide doctors recommendations on the best line of care, and may also give a sense of how well the patient will do in the immediate future.
Sources:
Miller, A. Neuro-oncology. Continuum: Lifelong Learning in Neurology. 2012, 18:2, 263-501
Ropper AH, Samuels MA. Adams and Victor's Principles of Neurology, 9th ed: The McGraw-Hill Companies, Inc., 2009.
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