Diagnosis of Nervous System Tumors
The first step in diagnosing a nervous system tumor involves evaluating the patient's symptoms and medical history. Diagnostic tests that may be performed to confirm the diagnosis, from a neurological exam, to computer imaging techniques, to surgical biopsy.
Neurological Exam & Nervous System Tumors
A neurological exam involves checking the patient's eye movements and reflexes, hearing, balance and coordination, movement, and various other sensations. Any obvious abnormalities in how a person senses the environment or how they move may suggest a neurological problem.
Neuro-imaging Techniques & Nervous System Tumors
To help determine if the problem is a result of a brain tumor or another neurological condition, special imaging techniques are used to observe the brain and detect any abnormal tumor mass.
- CT (computed axial tomography) scan involves using an x-ray machine and computer to obtain a computer image of an area of the body. Often, a dye is injected to improve the contrast between abnormal and normal tissue. In some cases, this test can be used to determine the type of tumor.
- MRI (magnetic resonance imaging) uses magnetic fields and a computer to obtain an image of the brain. This test produces more detailed images than CT scan, especially when tumors are located near bony structures. MRI scans provide images at various angles and are very useful for detecting swelling (edema) of brain tissue and bleeding (hemorrhage). As with CT scan, dye can be injected to improve the contrast between abnormal and normal tissue.
- PET (positron emission tomography) is used to measure brain activity. In this test, substances that can be monitored and used to evaluate tumor growth are injected. PET may be helpful in detecting recurrent tumors and in evaluating responses to chemotherapy and radiation treatment.
Brain Biopsy & Nervous System Tumors
A biopsy is the surgical removal of a small part of the tumor tissue to identify the exact type of tumor. Stereotactic biopsy uses computer guidance to determine the precise location of the tumor.
Using stereotactic technology, only a very small hole in the skull must be made. Prior to stereotactic surgery, a very wide opening in the skull was required for biopsy (called an open biopsy).
The complication rate for stereotactic brain biopsies is very low, and a correct diagnosis is made in more than 90 percent of cases. Sometimes, an open biopsy is necessary.
Tissue removed during biopsy is sent to a laboratory and is prepared and studied under a microscope by a pathologist. Based on the appearance of the cells and other characteristics, the type of tumor can be determined. If the tumor is malignant, the grade (i.e., how aggressive and fast-growing it is) can be determined.