There is no one test that can diagnose multiple sclerosis. The
following is a brief description of the tests your family doctor
and the neurologist may perform if you are suspected of having
multiple sclerosis.
» Medical History
Your doctor may ask you about current symptoms as well
as for a detailed medical history, which will include any
previous symptoms experienced.
» Neurological Exam
Your doctor may do an examination which looks for signs of
neurological impairment, or that your functions have been disrupted.
These include changes in reflexes, eye movements, coordination,
and gait (such as difficulty in walking).
» Magnetic Resonance Imaging (MRI)
MRI is the preferred way to help establish a diagnosis of multiple
sclerosis. The MRI scanner uses magnetic and radio waves to produce
detailed images of your brain and spinal cord. In MS, these images
will show damage to the myelin or nerve fibres in the brain and
spinal cord. These areas of damage are referred to as lesions,
scars (sclerosis), or plaques.
MRI can tell the difference between old lesions and those that
are new or active. The MRI scan is not painful or invasive. It
requires that a person lie very still on a narrow table within
the tunnel of the scanner. The tunnel is well lit and well ventilated,
and you can speak to the MRI technologist during the scan. Throughout
the scan you will hear loud clunking noises – the noises
are part of the magnetic / radio waves. These waves affect the
hydrogen (water) atoms in the brain and spinal cord, and allow
the doctor to see how MS may have damaged the myelin, which is
a fatty substance covering the brain and spinal cord.
Usually you can have the option of listening to a CD of your
choice during this time, or even watching a DVD. If you are uncomfortable
with being in small, enclosed spaces, be sure to let the person
doing the MRI know, so that they can help you through it as much
as possible.
» Testing of visual, auditory and somatosensory evoked potentials
These tests measure the speed at which messages in the brain
pass along the nerves. This can indicate if there is anything
wrong in the way the brain and spinal cord (central nervous system)
are working. In order to measure evoked potentials, wires are
placed on the scalp. The tests are not painful or invasive.
» Lumbar Puncture (or Spinal Tap)
This test can help determine if there are any signs of certain
antibodies and proteins in the cerebrospinal fluid (CSF). The
cerebrospinal fluid is the liquid which surrounds the brain and
spinal cord. The presence of certain antibodies and proteins
suggest an abnormal immune response, which could mean that your
immune system is attacking the myelin covering of the nerves
in the brain and spinal cord.
The test can be inconclusive. While an individual with MS will
likely have these proteins in their cerebrospinal fluid, having
these proteins does not necessarily mean that you have multiple
sclerosis.
This test is invasive as it involves inserting a needle into
the back. A local anesthesia is given so although the test is
uncomfortable it is not generally painful. It also requires the
individual to lay flat for several hours following the procedure,
and to drink fluids immediately after the spinal tap to guard
against dehydration (and a resulting headache).
Arriving at a diagnosis
The diagnosis of clinically definite multiple sclerosis requires
that there be signs of two neurological events (also known as
MS attacks or relapses). These attacks suggest that the individual
is experiencing loss of myelin in the brain and spinal cord.
The two attacks must occur in different areas of the brain and
spinal cord and occur at two separate times. An example of this
may be vision problems followed six months later by numbness
or tingling on one side of the body.
Studies have shown that people who have had a single sign or
symptom that suggests loss of myelin and who also have MRI-detected
brain lesions are at a higher risk of developing multiple sclerosis
within several years. People who may have experienced a single
attack but have no evidence of MRI-detected brain lesions are
at relatively lower risk for developing multiple sclerosis over
the same time period.
