Multiple Sclerosis

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Multiple Sclerosis

• How it affects us

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What is Multiple Sclerosis?

• Multiple Sclerosis (MS) is an inflammatory
  disease of the central nervous system (CNS).
• It is a disease of the white matter tissue.
• The white matter is made up of nerve fibers which
  are responsible for transmitting communication
  signals both internally within the CNS and
  between the CNS and the nerves supplying rest of
  the body.
• In people affected by MS, patches of damage
  called plaques or lesions appear in seemingly
  random areas of the CNS white matter.

• At the site of a lesion, a nerve insulating
  material, called myelin, is lost.
• MS is hard to characterize because it is very
  unpredictable and variable. Depending on which
  areas of the CNS are affected and how badly they
  are damaged, the type and severity of symptoms
  can vary greatly.
• People with MS experience partial or complete
  loss of any function that is controlled by, or
  passes through the brain or spinal cord.

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Continued

• People with MS can experience any of the
  following problems either fully or partially
• Numbness
• Tingling
• Pins and needles
• Muscle weakness
• Muscle spasms
• Spasticity
• Cramps
• Pain
• Blindness
• Blurred or double vision
• incontinence

• Urinary urgency or hesitancy
• Constipation
• Slurred speech
• Loss of sexual function
• Loss of balance
• Nausea
• Disabling fatigue
• Depression
• Short term memory problems
• Other forms of cognitive dysfunction
• Inability to swallow
• Inability to control breathing

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What happens to the myslin?
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1. Relapsing/Remitting(RRMS)
4 Types of MS

• This is characterized by relapses during which
  time new symptoms can appear and old ones
  worsen.. The relapses are followed by periods of
  remission, during which time the person fully or
  partially recovers from the deficits acquired
  during the relapse. Relapses can last for days,
  weeks or months and recovery can be slow and
  gradual. The majority of people presenting with
  MS are first diagnosed with relapsing/remitting.

• This is when the person is in their twenties or
  thirties, though diagnoses much earlier or later
  are known.
• Around twice as many women as men present with
  this variety.

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2. Secondary Progressive (SPMS)

• After a number of years many people who have had
  relapsing/remitting MS will pass into a secondary
  progressive phase of the disease.
• Characterized by a gradual worsening between
  relapses.
• In early phase, the person may still experience a
  few relapses but after a while these merge into a
  general progression.
• There are good and bad days but there is no real
  recovery.

• After 10 years, 50 of people with
  relapsing/remitting MS will have developed
  secondary progressive MS.

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3. Progressive Relapsing MS (PRMS)

• This form of MS follows a progressive course from
  onset, punctuated by relapses.
• There is significant recovery immediately
  following a relapse but between relapses there is
  a gradual worsening of symptoms.

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4. Primary Progressive MS (PPMS)

• Characterized by a gradual progression of the
  disease from its onset with no remissions at all.
• There may be periods of a leveling off of disease
  activity and as with secondary progressive, there
  may be good and bad days or weeks.
• PPMS differs from relapsing/remitting and
  secondary progressive in that onset is in the
  late thirties or early forties.

• Men are as likely as women to develop it and
  initial disease activity is in the spinal cord
  instead of the brain.
• Often migrates into the brain, but is likely to
  damage brain areas than relapsing/remitting or
  secondary progressive.

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What does MS Affect?
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• During periods of Multiple Sclerosis activity,
  white blood cells are drawn to regions of the
  with matter. These initiate and take part in what
  is known as the inflammatory response. The
  resulting inflammation is similar to what happens
  in your skin when you get a pimple.
• It seems that the inflammation also kills the
  maintenance glial cells, in particular it seems
  to kill the myelin-producing oligodendrocytes,
  which are lost in great numbers. Almost no
  oligodendrocytes persist in the middle of chronic
  MS lesions.
• As the disease progresses, axons are also
  destroyed though not necessarily by the
  inflammatory response. During the secondary
  progressive phase, inflammation becomes less and
  less common but still the axons continue to die.
  This degeneration of axons is known as Wallerian
  Degeneration.

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After axons have been demyelinated, several
things can happen

• The inflammation dies back. Neurons which have
  not been damaged by the relapse can resume their
  proper function and some recovery is usual, at
  least in the early stages of the
  relapsing/remitting form of the disease.
• Demyelinated axons can exhibit remarkable
  abilities to function despite losing their
  myelin. Recent work has shown that they produce
  greater numbers of sodium channels. These are
  special chemical gates which are integral in
  sending nerve transmitters down the neuron. This
  increased number of sodium channels contributes
  to remission in MS.
• The central nervous system is a very plastic
  organ and new neuronal pathways and connections
  can be created to get around the damaged neurons.
  This is anala goes to a motorist taking a minor
  road to avoid a traffic accident on their
  intended route. Although it is clear that this
  mechanisim contributes to remission, it is far
  from clear what the exact details are and much
  work remains to be done in this area.

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Continued

• The myelin maintenance cells in the CNS, the
  oligodendrocytes, can sponsor remyelination a
  process when the myelin sheath around the axon is
  repaired. Despite the fact that evoked potential
  tests show that remyelinated axons dont function
  quite as well as those which were never damaged
  in the first place, to the PwMS, this is
  sometimes not noticeable. Although remyelination
  usually only occurs at the edges of lesions, it
  still seems to be a contributing factor in
  remission.
• Remyelination may not take place or only happen
  partially, at least for a long time, due to
  oligodendrocytes not being around to promote it.
  When this happens the nerve will continue to
  function in an abnormal way as described above,
  but the axon remains undamaged. Sometimes after a
  long period of time, sometimes years, an axon
  will spontaneously become remyelinated and regain
  much of the function that had been presumed to be
  lost for good.

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Farther Continued

• The lost myelin can be replaced with scar tissue
  much like when you cut your hand a scar forms to
  join the separated areas of skin. This
  scarification is how Multiple Sclerosis got its
  name Multiple many and Sclerosis scar
  forming. Scar tissue can block the formation of
  new myelin and once axons have become scarified
  they do not fully regain their former function.
• The underlying axon can become withered and
  function lo9st entirely. Needless to say a
  withered axon will never function at all again.
  Continuing our electrical wire analogy, this is
  rather like snipping the cable with wire cutters.

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For more information go to
http//www.mssociety.ca/
http//medstat.med.utah.edu/kw/ms/