GBS

Question 1

What is GBS

Answer 1

Guillain-Barré syndrome is an acute paralytic polyneuropathy.

It is an autoimmune, rapidly progressive demyelinating condition of the peripheral nervous system, often triggered by infection

Question 2

Epidemiology of GBS

Answer 2

• GBS is a rare condition.
• M>F
• Peak incidence between 15-35 years old and 50-75 years old
• A key risk factor is an infection in the preceding 6 weeks, with 60% of cases being linked to a prior infection as the trigger.

Question 3

RFs for GBS

Answer 3

• Male:slightly more common in males than females (1.8:1)
• Age:peak incidence between 15-35 years old and 50-75 years old
• Infections:typically gastrointestinal or respiratory:
  
  • Bacterial:e.g. Campylobacter jejuni (30%) and mycoplasma pneumoniae
  • Viral:e.g. Zika virus, influenza, Epstein-Barr virus and cytomegalovirus
• Malignancies:lymphoma may increase the risk of GBS
• Vaccines:association with the influenza vaccination (uncommon)

Question 4

What is the pathophysiology of GBS

Answer 4

• A pathogenic antigen(e.g.Campylobacter jejuni) resembles myelin gangliosides in theperipheral nervous system
• The immune systemtargets the antigen and attacksthemyelin sheath of sensory and motor nerves
• Thisautoimmune processinvolves the production ofanti-ganglioside antibodies(anti-GMI is positive in 25% of patients)
• The demyelination occurs in patches along the length of the axon, so it’s called segmental demyelination
• Early on, there is remyelination but over time, there’s irreversible damage

Question 5

What are the different subtypes of GBS based on?

Answer 5

which type of nerves are demyelinated

Question 6

What are the different subtypes of GBS

Answer 6

• Acute demyelinating inflammatory**polyneuropathy (ADIP):~90% of cases
• Acute motor axonal neuropathy (AMAN)
• Acute motor and sensory axonal neuropathy (AMSAN)
• Miller-Fisher Syndrome (MFS)

Question 7

What is Miller-Fisher Syndrome (MFS)?

Answer 7

• Classic triad: ataxia, areflexia, and ophthalmoplegia
• Eye musclesare typically affected first
• Usually causes descending(rather than ascending) paralysis and anti-Gq1b antibodies are present in 90% of cases

Question 8

Signs of GBS

Answer 8

• Reduced sensation in affected limbs: sensory findings on examination are usually mild
• Symmetrical weakness in lower extremities first, progressing to the upper limbs: proximal muscles often affected earlier than distal muscles
• Ataxia with hyporeflexia (or areflexia) in affected limbs
• Autonomic dysfunction: e.g. tachycardia, hypertension, postural hypotension, urinary retention (in severe disease)
• Respiratory distress: shortness of breath, respiratory muscle weakness requiring mechanical ventilation in severe cases
• Cranial nerve involvement and bulbar dysfunction: e.g. diplopia or facial droop

Question 9

Symptoms of GBS

Answer 9

• Tingling and numbness in hands and feet: often precedes muscle weakness
• Symmetrical, progressive, ascending weakness
• Unsteady when walking
• Back and leg pain: common at some point in disease course
• Shortness of breath
• Facial weakness and speech problems
• Loss of Deep tendon reflexes
• Resp failure in 35%

Question 10

What is a clinical diagnosis of GBS evidenced by?

Answer 10

clinical diagnosis evidenced by progressive weakness and areflexia (or hyporeflexia) in the weaker limbs. The Brighton criteria is used for diagnosis.

Question 11

Primary investigations for GBS

Answer 11

• U&Es: electrolyte abnormalities resulting in neuropathic symptoms
• B12 and folate: deficiency associated with neurological features
• TFTs: to exclude hypothyroidism as a cause of weakness
• LFTs: elevation of hepatic enzymes is associated with more severe disease
• Anti-ganglioside antibodies: can be used to differentiate GBS variants, e.g. anti-GQ1b antibody in Miller-Fisher syndrome
• Cultures:stool or sputum sample if there are ongoing infective features, e.g. gastroenteritis
• Lumbar puncture for CSF:raised proteinwithnormal WBC countis typical, although an initial normal protein level does not exclude GBS
• Spirometry: to monitor respiratory function as 20% of patients require mechanical ventilation at some stage

Question 12

What are the other investigations to consider

Answer 12

• Nerve conduction studies: not required for diagnosis; findings will typically be suggestive of demyelination, e.g. reduced conduction velocity
• MRI brain and spinal cord:to differentiate between GBS and other possible neurological causes, e.g. transverse myelitis

Question 13

DDs for GBS

Answer 13

• Transverse myelitis
• Myasthenia gravis
• Lambert-eaton myasthenic syndrome
• Botulism
• Polymyositis
• Vasculitic neuropathy

Question 14

What is the 1st line management for GBS

Answer 14

• IV immunoglobulins (IVIg):5 day treatment course commenced within the first 2 weeks of symptom onset,OR
• Plasma exchange: 5 treatments of 2-3L over 2 weeks commenced within the first 4 weeks of symptom onset

Question 15

What do you give to patients who are IgA deficient?

Answer 15

CI in IgA deficient patients; allergic reaction

Question 16

What is the additional management that must be done for GBS

Answer 16

• Thromboprophylaxis:to prevent venous thromboembolism
• Physiotherapy:for those with impaired mobility or motor disturbance
• Intensive care support:for those who develop ventilatory failure (20%), intensive care and mechanical ventilation may be required

Question 17

Complications of GBS

Answer 17

• Type 2 respiratory failure:if respiratory muscles are affected; may require mechanical ventilation in intensive care
• Impaired mobility:may persist for months to years after the initial onset of GBS
• Pulmonary complications: including infections due to intubation, or pulmonary emboli due to immobility and a pro-inflammatory state
• Autonomic dysfunction: dysfunction of the bowel (ileus) and bladder (retention) may occur, as may arrhythmias, and variations in heart rate and blood pressure
• Psychiatric impact: depression, post-traumatic stress disorder and anxiety are all associated with GBS