What does an MRI show?
The precise image produced by MRI gives the neurologist clear evidence of scar tissue in the deep parts of the brain or spinal cord that is characteristic of MS.
However, abnormal spots on the brain MRI can be caused by other conditions, so these images must be interpreted by the neurologist in light of all information about the patient. Similar lesions can be seen in elderly people or people with migraine headaches or high blood pressure. Confirming a diagnosis of MS and ruling out other possible causes requires expert interpretation of the MRI scan.
Will I need a spinal tap?
Performing a spinal tap to examine the cerebrospinal fluid might be helpful in diagnosing MS in some people, but it is no longer considered necessary in all instances.
An experienced MS team will be able to determine if you need this test to confirm a suspected diagnosis of MS, particularly if your history and physical examination suggest the presence of the disease. Abnormalities that might appear in the cerebrospinal fluid can be very helpful in establishing a diagnosis but, like other tests, spinal taps are not foolproof in diagnosing MS.
What other tests might be done?
Electrical tests of the nerve pathways, known as evoked potentials, are very helpful in confirming whether MS has affected the visual, auditory, or sensory pathways. These tests are done by placing wires on the scalp to test the brain's response to certain types of stimulation, such as watching a pattern on a video screen, hearing a series of clicks, or receiving electrical impulses in your arm or leg.
Your doctor might order a blood test to help rule out conditions that imitate multiple sclerosis, but the presence of MS cannot be detected in the blood.