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Diagnosis

There is no laboratory test, symptom, or physical finding which, when present or positive, always means a person has MS. In addition, some of the symptoms of MS could also be caused by other diseases.

Consequently, the diagnosis of MS must be made by a careful process which demonstrates findings that are consistent with MS and that also rules out other causes.

The basic "rule" for diagnosing MS relies on two criteria:

  1. There must have been two attacks at least one month apart. An attack, also known as an exacerbation, flare, or relapse, is a sudden appearance of or worsening of an MS symptom or symptoms which lasts at least 24 hours.
  2. There must be more than one area of damage to central nervous system myelin - the sheath that surrounds and protects nerve fibers. The damage to myelin must have occurred at more than one point in time and not have been caused by any other disease that can cause demyelination or similar neurologic symptoms.

MRI is the preferred method of imaging the brain

MRI (magnetic resonance imaging) is currently the preferred method of imaging the brain to detect the presence of plaques or scarring caused by MS. It is better at detecting plaques than CT scanning. Often brains that appear to be normal on CT scans will be shown to have plaques on MRI. Still, the diagnosis of MS cannot be made solely on the basis of MRI. There are other diseases that cause lesions-areas of damage in the brain that look like those caused by MS. There are also spots found in healthy individuals, particularly in older persons, that are not related to any ongoing disease process.

On the other hand, a normal MRI does not absolutely rule out a diagnosis of MS. About 5% of patients who are confirmed to have MS on the basis of other criteria, do not show any lesions in the brain on MRI. These people may have lesions in the spinal cord or may have lesions which cannot be detected by MRI.

Clinical exam includes history and tests of function

Other symptoms of MS will be evaluated during the clinical examination conducted by a physician.This covers an extensive review of mental, emotional and language functions, movement and coordination, vision, balance and the functions of the five senses. Sex, birthplace, family history and age of the person when symptoms first began are also taken into consideration.

Sometimes other tests are needed

It is not usually necessary to do all diagnostic tests for every patient. If, however, a clear-cut diagnosis cannot be made based on the tests above, additional tests may be ordered. These include tests of evoked potentials, cerebrospinal fluid and blood.

Evoked potential tests are electrical diagnostic studies which can show if there is a slowing of messages in the various parts of the brain. They often provide evidence of scarring along nerve pathways that is not apparent on a neurologic exam. Cerebrospinal fluid, usually taken by a spinal tap, is tested for levels of certain immune system proteins and for the presence of oligoclonal bands. These bands indicate an abnormal autoimmune response within the central nervous system,meaning the body is producing an immune response against itself. Oligoclonal bands are found in the spinal fluid of about 90-95% of people with MS, but since they are present in other diseases as well cannot be relied on as positive proof of MS. They may also take some years to develop.While there is no definitive blood test for MS, blood tests can rule out other causes for various neurologic symptoms. Some other conditions that cause symptoms similar to those of MS are Lyme disease, a group of diseases known as collagen-vascular diseases, certain rare hereditary disorders and AIDS.

Source - NMSS Information Resource Center and Library. Compendium of Multiple Sclerosis Information (CMSI). 1997, US National Multiple Sclerosis Society. Rev. 10/97. Reproduced with permission.

About Magnetic Resonance Imaging (MRI). What is MRI?

Magnetic Resonance Imaging (MRI) is a technique that produces detailed images of the inside of your body. These images produce a clear picture of your internal organs and soft tissues, from many different angles. Dozens of images may be produced during any one scan, depending on your doctor's request.

MRI works by using radio waves (similar to those emitted by your TV antenna) and magnetic fields, in conjunction with special computers. The magnetic field that is produced prepares the cells of your body to reflect radio "signals". The signals reflected by any abnormal cells are identifiable on the image or "picture" that is produced. MRI is therefore an important and very useful tool in the location and diagnosis of abnormalities of the brain, spine, joints and internal organs.

Is MRI safe?

The radio and magnetic waves used during MRI are in themselves safe and no adverse health or side effects have been reported following normal exposures. There is no radiation or x-ray involved in the procedure.

However if you have:

You need to inform you doctor prior to the examination as the procedure may not be suitable for you. There has been no evidence to suggest that MRI is hazardous to pregnant women. However, if you are pregnant or suspect you may be, you should inform your doctor.

What do I have to do to prepare for the scan?

Unless you are already in hospital, you will be tested as an outpatient. There are no dietary or other restrictions prior to MRI. You may like to practice relaxation techniques such as meditation, breathing exercise or guided imagery. These may prove useful during the scan.

Immediately prior to the scan, you will be asked to remove all metal objects including:

You may also be asked to remove any excess make-up. You will then be provided with a hospital gown to wear during the procedure.

What will happen during the scan?

MRI scan procedure is very simple. You will be asked to lie very still on a padded "bench" which is then moved slowly into the scanner. The scanner itself is a long, well-lit tunnel, open at both ends. If particular information is required about specific organs, you may be given an injection of a special fluid (contrast agent) prior to the procedure, to allow for greater detail.

During the examination, you will hear a loud knocking sound. This is just the machine working during the scan. Earplugs or music earphones will be provided and you are welcome to bring your own music or relaxation tapes. Special reflective glasses can also be provided if you would like to see out of the end of the tunnel. Throughout the procedure you will be in voice contact with MRI staff, who will keep you informed of what is happening.

Can I have someone with me during the scan?

Yes. Friends(s)/relative(s) may be invited to sit in the room and converse with you during the scan. Parents may like to be there with their children during the procedure. Visitors will also be required to remove any metal objects (jewellery, etc) before entering the room, so as not to interfere with the magnetic field.

Will I feel anything during the scan?

No, however, the enclosed nature of the scanner may cause some people to experience certain levels of anxiety. If you have any history of panic reactions, or feel this may be a problem, you should talk to your doctor and inform the radiographer prior to the examination. Many people have found talking to someone, wearing special reflective glasses and/or listening to their own music or relaxation tapes help during the procedure. In severe cases, a sedative can be provided.

How long will the scan take?

The MRI scan will take from 30 to 60 minutes, averaging 40 minutes, depending on the amount and type of information required. During this time, you must lie very still, as any movement can cause an unclear sequence of pictures which may then need to be repeated.

What happens after the scan?

You may leave the hospital immediately after your scan. However, if you have had a sedative, it is advisable that you have someone to accompany you home. Your pictures are interpreted by the radiologist and the images and results are then sent to your doctor as soon as possible. You should consult your doctor to arrange a date and time to discuss the results of your scan.

Source - Information Booklet. MRI Department - Epworth Hospital. Reproduced with permission.

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