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Diagnosing
Multiple Sclerosis
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.
To read more about this study, please click
here.
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