Saturday, 16 October 2010

MRCP revision battle 31.3: Multiple Sclerosis

Multiple sclerosis is a cell-mediated autoimmune disorder characterised by plaques of demyelination at sites throughout the CNS but not in the peripheral nerves.

4 main types:
  1. relapsing-remitting
    • accounts for 80% of cases
  2. secondary progressive
    • up to 50% of relapsing-remitting patients eventually develop this
  3. primary progressive
    • 10-15% of cases
    • older age of onset
  4. progressive-relapsing

Initial presentation tends to be a single symptom, such as:
  • optic neuritis 
    • pain on eye movement and rapid deterioration in central vision, loss of colour vision
    • treatment is methylpred
    • single episode gives 40-60% chance of subsquent MS
  • numbness or tingling in limbs
  • leg weakness
  • ataxia

Diagnosis is by (NB none is specific):
  • lesions disseminated in time and location
  • T2 weighted MRI showing demyelinating plaques
  • delayed visual evoked response potentials
  • oligoclonal bands in CSF but not serum

Good prognostic factors are:
  • relapsing-remitting course
  • female
  • young onset
  • sensory symptoms

Risk of MS is increased 20-40% in siblings and there is 25% concordance in monozygotic twins.

Treatment is:
  • IV methylprednisolone
    • shortens relapses
    • no effect on incidence of attacks
  • beta interferon
    • decreases relapses by 30%
    • given if
      • relapsing-remitting course and 2 relapses in 2 yrs and can walk 100m unaided
      • secondary progressive and 2 relapses in 2 yrs and 100m aided
    • side effect: flu-like
  • baclofen
    • decreases spascity

Now for the less heavy-going Menieres disease...