The likely diagnosis in this case is Miller Fisher syndrome, a variant of Guillain-Barré syndrome, characterised classically by a triad of ataxia, areflexia and ophthalmoplegia.
Guillain-Barré syndrome, and its variants such as Miller Fisher, are the result of an autoimmune response, causing an acute inflammatory polyneuropathy. This autoimmune response is in reaction to a stimulus to the immune system. In this case, it is likely the result of a Campylobacter Jejuni enteritis (accounting for 25-50% of causes). Other causes include viral illnesses such as Influenza, CMV and EBV; Mycoplasma infection; and vaccinations.
Clinical features of Guillain-Barré syndrome include:
- Bilateral ascending motor weakness
- Areflexia
- Paraesthesia
- Miller Fisher variant – cranial nerve involvement and bulbar symptoms
- Respiratory failure from muscle weakness
- Autonomic dysfunction – including dysrhythmias, diarrhoea and vomiting, decreased sweating, labile blood pressure
