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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
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Myasthenia gravis
QuestionChoice
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
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Guillain-Barré Syndrome
QuestionChoice
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
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Miller Fisher syndrome
QuestionChoice
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
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Acute brainstem stroke
QuestionChoice
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
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Wernicke encephalopathy
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The question implies that the weakness started in the face and progressed to arms and then legs which is the opposite of GBS and was very confusing
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Agreed
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Zika Complement
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exactly!
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Prognosis Kawasaki
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yes, it's atypical GBS, but it does happen and more commonly than miller fisher
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Ale
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if it was atypical GBS, why didn't they give an explanation that mentions that it is atypical? Literally says here that GBS presents with a symmetrical ascending flaccid paralysis of the lower limbs, with 0 mention of any atypical presentations
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## Summary

Guillain-Barré Syndrome (GBS) is an acute inflammatory demyelinating polyneuropathy characterised by a rapid, progressive, ascending symmetrical weakness, often preceded by infection. Diagnosis is largely clinical but supported by specific investigations such as lumbar puncture and nerve conduction studies. Treatment is mainly supportive, with options for disease-modifying treatments like intravenous immunoglobulins (IVIG) or plasmapheresis in severe cases.

## Definition

GBS is an ascending inflammatory demyelinating polyneuropathy, typified by an acute onset of bilateral and roughly symmetric limb weakness. 

## Epidemiology

The prevalence of GBS is approximately 1-2 cases per 100,000 worldwide.

## Aetiology

GBS typically occurs 1-3 weeks following an infection, with common culprits being Campylobacter, mycoplasma, and Epstein-Barr Virus (EBV). 

40% of cases, however, are idiopathic. 

Other potential triggers include infections such as CMV, HIV, Hepatitis A, or following certain vaccinations such as for tetanus, rabies, or swine flu.

## Signs and symptoms

Neurological decline often progresses over days to weeks.

Clinical features of GBS include:

- Progressive ascending symmetrical limb weakness (usually starting with the lower limbs)
- Lower back pain due to radiculopathy
- Paraesthesia, often preceding motor symptoms
- Potential respiratory muscle involvement in severe cases
- Potential cranial nerve involvement leading to diplopia, facial droop
- **Lower motor neurone** signs in the lower limbs: hypotonia, flaccid paralysis, areflexia
- Cranial nerve signs: ophthalmoplegia, lower motor neurone facial nerve palsy, bulbar palsy
- Potential autonomic dysfunction (e.g., arrhythmia, labile blood pressure)

## Variants

Several variants of GBS exist, each presenting with unique characteristics:

- Paraparetic variant
  - Primarily affects the lower limbs

- Miller-Fisher syndrome
  - Presents with ataxia, ophthalmoplegia, and areflexia
  - Associated with **anti-GQ1B antibodies**

- Pure motor variant
  - Ascending weakness without sensory involvement

- Bilateral facial palsy with paraesthesias
  - Affects the cranial nerves

- Pharyngeal-brachial-cervical weakness
  - Results in weakness of the upper limbs
  - Associated with **anti- GT1a antibodies**
- Bickerstaff's Brainstem Encephalitis
  - Presents with encephalitis, ophthalmoplegia, and ataxia

It's worth noting that these variants rarely present purely as described, and there's often overlap in clinical presentation.


## Differential diagnosis

- Vascular: occasionally, brainstem strokes may present similarly
- Infective/Inflammatory: 
  - Polio: asymmetrical weakness from myelitis
  - Lyme disease
  - CMV
  - HIV
  - TB
  - Transverse myelitis 
  - Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) 
  - Myasthenia gravis
- Traumatic/Structural:
  - Spinal cord compression
- Metabolic:
  - Porphyrias: may result in an acute neuropathy
  - Electrolyte derangements: hypokalaemia, hypophosphataemia, hypermagnesaemia
	

## Investigations

Investigations for GBS include:

- Monitoring of forced vital capacity (FVC) for respiratory muscle involvement
- Cardiac monitoring for autonomic instability
- Blood tests, including arterial blood gas (ABG)
- Serological tests: Anti-ganglioside antibodies
- Lumbar puncture: may show **albuminocytological dissociation** 
	- Increased level of protein (albumin) without a corresponding increase in white blood cells (cytology)
- Nerve conduction studies
	- May show prolongation or loss of the F wave
- Identification of the underlying cause: stool cultures, serology, CSF virology

## Management

Management of GBS is primarily supportive and includes:

- Regular monitoring of FVC
	-  Early involvement of intensive care is essential if any reduction in FVC as deterioration may be rapid
- Venous thromboembolism (VTE) prophylaxis: TEDS + LMWH
- Analgesia: NSAIDs or opiates for radiculopathy-related back pain
- Management of cardiac arrhythmias as per ALS guidelines
- Careful use of antihypertensives due to potential autonomic dysfunction
- Consideration of enteral feeding in those with unsafe swallow

Specific medical management for those with significant disability (e.g., inability to walk) include:

- Intravenous immunoglobulin (IVIG) over a 5-day course
- Plasmapheresis, which has similar efficacy to IVIG but is associated with more side effects.

## Prognosis

While GBS can be life-threatening, particularly when respiratory muscles are affected or in the presence of autonomic dysfunction, the majority of patients experience full recovery. 

However, residual fatigue and weakness can persist in some patients. Certain variants of GBS, like Miller-Fisher syndrome, generally have a good prognosis with full recovery being the norm. 

Prognostic indicators include speed of onset, severity at nadir, age and the presence of preceding diarrhoeal illness.

## References

1. Van den Berg, B., Walgaard, C., Drenthen, J., Fokke, C., Jacobs, B. C., & Van Doorn, P. A. (2014). Guillain–Barré syndrome: pathogenesis, diagnosis, treatment and prognosis. Nature Reviews Neurology, 10(8), 469-482.

2. Yuki, N., & Hartung, H. P. (2012). Guillain–Barré syndrome. New England Journal of Medicine, 366(24), 2294-2304.

3. Hughes, R. A., & Cornblath, D. R. (2005). Guillain-Barré syndrome. The Lancet, 366(9497), 1653-1666.

4. Willison, H. J., Jacobs, B. C., & Van Doorn, P. A. (2016). Guillain-Barré syndrome. The Lancet, 388(10045), 717-727.

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