A neurologic evaluation should be done if a patient has slowly increasing signs of mental dysfunction, new seizures, persistent headaches or evidence that there is pressure inside the skull (such as vomiting or swelling or protrusion of the blind spot at the back of the eye). A neurologist (a doctor who has received special additional training in the diagnosis and treatment of disorders of the brain, spinal cord and nerves) will perform a complete examination.
He or she may also request that a magnetic resonance imaging (MRI) scan or a computed tomography (CT or CAT) scan be done, as well as chest X-rays, to determine if the tumor has spread from another part of the body. An MRI usually finds low-grade astrocytomas earlier than CT. Cerebral angiography is rarely used to diagnose a brain tumor, but it may be done before surgery.
Depending on the patient's symptoms, specialized tests may be done, including tests of the field of vision, the sharpness of vision and hearing. If the results of other tests are not conclusive, an examination of the fluid that surrounds the brain and spinal cord may be done, although it is usually unnecessary. It is essential for diagnosing chronic or subacute meningitis or for identifying benign hypertension inside the skull.