Guillian Barre Syndrome Flashcards

1
Q

What is GBS

A

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

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2
Q

Epidemiology of GBS

A
  • 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.
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3
Q

RFs for GBS

A
  • 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)
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4
Q

What is the pathophysiology of GBS

A
  • 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
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5
Q

What are the different subtypes of GBS based on?

A

which type of nerves are demyelinated

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6
Q

What are the different subtypes of GBS

A
  • Acute demyelinating inflammatory**polyneuropathy (ADIP):~90% of cases
  • Acute motor axonal neuropathy (AMAN)
  • Acute motor and sensory axonal neuropathy (AMSAN)
  • Miller-Fisher Syndrome (MFS)
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7
Q

What is Miller-Fisher Syndrome (MFS)?

A
  • 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
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8
Q

Signs of GBS

A
  • 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
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9
Q

Symptoms of GBS

A
  • 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%
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10
Q

What is a clinical diagnosis of GBS evidenced by?

A

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

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11
Q

Primary investigations for GBS

A
  • 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
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12
Q

What are the other investigations to consider

A
  • 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
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13
Q

DDs for GBS

A
  • Transverse myelitis
  • Myasthenia gravis
  • Lambert-eaton myasthenic syndrome
  • Botulism
  • Polymyositis
  • Vasculitic neuropathy
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14
Q

What is the 1st line management for GBS

A
  • 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
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15
Q

What do you give to patients who are IgA deficient?

A

CI in IgA deficient patients; allergic reaction

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16
Q

What is the additional management that must be done for GBS

A
  • 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
17
Q

Complications of GBS

A
  • 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