🎯 Pathology

• rare acute, immune-mediated demyelinating peripheral neuropathy

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💡 Causes

• may be triggered by infections such as

  • gastrointestinal infections caused by Campylobacter jejuni (classical trigger)

  • respiratory infections caused by Mycoplasma pneumoniae

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 🩺 Clinical features

• general points

  • presents within 1 to 6 weeks of illness

  • symptoms are symmetrical

  • affects both the upper and lower limbs

  • motor symptoms are more marked than sensory symptoms

• typical signs and symptoms

  • initial symptom: back and leg pain

  • ascending flaccid muscle paralysis (the lower extremities are affected first)

  • hyporeflexia or areflexia

  • mild paresthesias in the hands and feet

• other features

  • respiratory weakness

  • this leads to hypoventilation, which is a cause of type 2 respiratory failure

  • cranial nerve palsies

    • CN III, IV, VI: extraocular muscle weakness

    • CN VII: facial weakness

    • CN IX and CN X: oropharyngeal weakness leading to dysphagia potentially resulting in aspiration

  • autonomic symptoms

    • postural hypotension

    • sinus tachycardia

    • urinary retention

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⚡️ Miller-Fisher syndrome

• a variant of Guillian-Barre syndrome (GBS)

• classical triad:

  • areflexia

  • ataxia

  • ophthalmoplegia

• more than 90% of people with Miller-Fisher syndrome have antibodies to anti-GQ1B (a type of ganglioside antibody)

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🕵️‍♂️ Investigations

• thorough history and full neurological examination

• nerve conduction studies

  • should be done within 7 to 14 days following the onset of symptoms

  • typical findings:

    • decreased conduction velocity (due to demyelination)

    • prolonged/absent F-wave latencies

    • prolonged distal latencies

    • prolonged/absent H-reflex

• lumbar puncture

  • CSF shows albuminocytologic dissociation which means:

    • elevation in the protein content with normal white cell count in the CSG

• bloods

  • consider testing for anti-ganglioside antibodies if lumbar puncture results are equivocalthere are different types of anti-ganglioside antibodies that are associated with GBS

    • anti-GM1

    • anti-GD1A

    • anti-GT1A

    • anti-GQ1B (present in more than 90% of people with Miller-Fisher syndrome)

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💆‍♂️ Management

• intravenous immunoglobulin (IVIG)

• plasma exchange

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🧲 High-yield tips

• evidence shows that systemic steroids are NOT beneficial

• more than 80% of patients will mobilise independently within 6 months​​