Frequently Asked Questions
Questions Often Asked About How Multiple Sclerosis is Diagnosed
Q: How is MS diagnosed?
A: A diagnosis of MS usually begins with a discussion of your symptoms and medical history with your doctor. This is often followed by neurological examinations, including an MRI scan. Published criteria cite the incidence of two separate attacks of the illness, and two or more lesions in the white matter of the central nervous system, confirmed by an MRI, as requirements of an MS diagnosis.
Other commonly performed laboratory tests are lumbar puncture to detect abnormal proteins or other substances within the cerebral spinal fluid, and evoked potentials to measure the speed of nervous system transmissions that may indicate damage due to MS.
Q: What are evoked potentials, and why are they measured in MS diagnosis?
A: By measuring what are known as evoked potentials or evoked responses, certain nerve fibres can be checked. This means that when MS is present, it is possible to see whether certain nervous impulses are slowed down in the nerve fibres (because of demyelination). The more demyelination, the slower the transmission of impulses measured.
There are several different types of evoked potential test that can be performed to measure the response time of various nerve impulses throughout the body. Each one tests the transmission of nerve impulses from the brain to a specific part of the body that controls different body functions, such as hearing, sight, or motor function. A neurologist may wish to perform just one or all of these tests.
Q: What is a lumbar puncture (spinal tap)?
A: This examination involves inserting, under local anaesthetic, a hollow needle through the lower back ('lumbar') to take a sample of the fluid surrounding the brain and spinal cord (the ‘cerebrospinal fluid’).
This fluid in people with MS shows specific changes that match up with the presence of inflammation: slightly more inflammatory cells and greater number of inflammatory proteins.
About 20% of all those who undergo this examination get headaches and dizzy spells, but these usually clear up after a few hours.
Q: What is an MRI scan?
A: The MRI, short for Magnetic Resonance Imaging, is done using a machine that uses a strong magnetic field to create cross-sectional images or ‘scans’ of the brain and spinal cord. During a scanning session, the patient lies down within a circular magnet in the MRI machine. There are no known adverse effects from MRI tests.
MRI scans show any inflamed myelin or other defects in the white matter. An MRI scan can show how much scar tissue has accumulated over time due to MS activity. It allows neurologists to:
- Eliminate many alternative disorders that have similar symptoms to MS.
- Predict the probability that any given individual will experience recurrent symptoms and disability over the 5 years after onset of the disease.
- Determine the true activity of the disease during the quiet or relapsing phase.
- An MRI is often obtained at the onset of symptoms to establish a diagnosis and to establish a baseline before beginning treatment. Once on therapy, it is reasonable to repeat MRI scans periodically to determine the extent of inflammation or brain lesions.
Q: Where can I find more resources on diagnosing MS?
A: Your neurologist should be your first point of contact to help diagnose whether you have MS or not and to answer any specific questions you have.
- We offer some resources on this site that will help you gain a better understanding of MS diagnosis.
- Our Living Library offers articles and other resources. You can also click here for more information.