A 20-year-old male presents to Accident & Emergency with a one-week history of bilateral facial weakness and progressively weak arms and legs. Prior to this, he had an acute diarrhoeal illness which has since settled. He has no other past medical history.

His Glasgow coma scale (GCS) score is 15. On examination, he has a bilateral facial palsy, bilateral symmetrical lower and upper limb weakness and reduced tendon reflexes.

He has a sudden onset desaturation whilst on the general medical ward and is transferred to the intensive care unit for intubation and ventilation.

Which of the following is the most likely diagnosis?

Options:
explanation: This is a possible differential, as this may cause a bilateral facial palsy. However the progression of muscle weakness in myasthenia gravis is typically descending from the extraocular muscles to the face and limb girdle. Deep tendon reflexes are not affected. The clinical course is also longer in myasthenia gravis and may occur over months to years
name: Myasthenia gravis
label: e
answer: no
explanation: Guillain-Barré Syndrome (GBS) typically presents with a symmetrical ascending flaccid paralysis of the lower limbs that later spreads to the trunk and may later affect the respiratory muscles. Areflexia may also be present. Bilateral facial nerve palsy can occur in Guillian Barre Syndrome. Miller Fisher syndrome is a valid differential. However, it should be remembered that Miller Fisher syndrome is extremely rare and it is still much more likely to encounter patients with GBS who have atypical features
name: Guillain-Barré Syndrome
label: a
answer: yes
explanation: This is a possible differential here and may also present with respiratory dysfunction. However, this tends to follow a more acute onset compared to GBS, and focal neurological symptoms such as weakness are not typically symmetrical. Stroke, as an upper motor neurone pathology, is also unlikely to cause hyporeflexia
name: Acute brainstem stroke
label: c
answer: no
explanation: Miller Fisher syndrome (MFS) presents as a triad of ataxia, areflexia and ophthalmoplegia. In this case, the predominant symptoms are of symmetrical ascending weakness, which has now likely extended to involve the chest muscles. You might also expect evidence of opthalmoplegia which is absent in this case. Bilateral facial nerve palsy can occur in Guillian Barre Syndrome. Miller Fisher syndrome is a valid differential. However, it should be remembered that Miller Fisher syndrome is extremely rare and it is still much more likely to encounter patients with GBS who have atypical features
name: Miller Fisher syndrome
label: b
answer: no
explanation: This is an unlikely differential here, as it typically presents with confusion, ataxia and ophthalmoplegia (nystagmus is a common finding). This patient does not present with altered mental status and does not appear to have risk factors for thiamine deficiency, e.g. chronic alcoholism, malnutrition, malabsorption or gastrointestinal disease
name: Wernicke encephalopathy
label: d
answer: no

Correct answer: a


Learning point: Guillain-Barré Syndrome presents with symmetrical ascending flaccid paralysis, often following an infection with camplyobacter.