Peripheral neuropathies

Hereditary motor sensory neuropathies
1. -> symmetrical slowly progressive distal muscular wasting
2. type I
  1. aka peroneal muscular atrophy (Charcot-Marie-Tooth disease)
  2. dominantly inherited
  3. commonest type
  4. affected nerves hypertrophy
    1. due to demyelination fb attempts @ remyelination
      1. so nerve biopsy shows 'onion bulb formation'
  5. onset
    1. 1st decade
      1. presentation
        distal atrophy
        pes cavus
        legs> arms affected
        distal sensory loss & diminished reflexes
        rare
        loss of walking ability is rare
        initial presentation of Friedreich ataxia can be similar
  6. chronic course
acute post-infectious polyneuropathy (Guillain-Barre syn)
1. presentation
  1. 2-3 weeks ff
    1. upper resp tract infection
    2. campylobacter gastroenteritis
  2. fleeting abnormal sensory sx in legs
  3. prominent feature
    1. ascending symmetrical weakness
      1. w/ loss of reflexes
        & autonomic involvement
  4. sensory sx in distal limbs
  5. bulbar mm involvement
    1. difficulty chewing & swallowing
    2. risk of aspiration
  6. max mm weakness
    1. occurs 2-4 weeks after onset of illness
2. full recovery expected in 95% of cases
  1. may take up to 2 years
3. Ix
  1. CSF protein
    1. sig raised
      1. characteristic
      2. may not be seen till 2nd wk of illness
  2. CSF WCC
    1. not raised
  3. nerve conduction velocities
    1. reduced
4. Mx
  1. supportive
    1. respiration
      1. ventilator
  2. NOT USEFUL
    1. corticosteroids
  3. immunoglobulin infusion
    1. reduce time on ventilator
    2. if unsuccessful
      1. use plasma exchange
Bell palsy & facial nerve palsies
1. Bell's palsy
  1. isolated lower motor neurone paresis of CN7
    1. -> facial weakness
  2. aetiology unclear
    1. but probably post-infectious
      1. assoc w/ herpes simplex in adults
  3. Mx
    1. Rx
      1. corticosteroids
        to reduce oedema in the facial canal during the 1st week
      2. NO USE
        aciclovir
  4. recovery may take several months
  5. complications
    1. conjunctival infection
      1. caused by incomplete eye closure on blinking
        eye protection or tarsorrhaphy
  6. differential diag
    1. features of Bell's + sx of CN7 paresis
      1. compressive lesion in cerebellopontine angle
        most likely diag
      2. painful vesicles on tonsillar fauces, external ear
        due to HSV invading geniculate ganglion
        Rx = aciclovir
    2. hypertension
      1. cos assocn btw Bell's palsy and coarctatin of aorta
    3. if facial weakness bilat
      1. sarcoidosis
      2. Lyme disease

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Peripheral neuropathies

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	Created by v.djabatey almost 11 years ago