Guillian Barre Syndrome Flashcards
What is GBS
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
Epidemiology of GBS
- 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.
RFs for GBS
- 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)
What is the pathophysiology of GBS
- 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
What are the different subtypes of GBS based on?
which type of nerves are demyelinated
What are the different subtypes of GBS
- Acute demyelinating inflammatory**polyneuropathy (ADIP):~90% of cases
- Acute motor axonal neuropathy (AMAN)
- Acute motor and sensory axonal neuropathy (AMSAN)
- Miller-Fisher Syndrome (MFS)
What is Miller-Fisher Syndrome (MFS)?
- 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
Signs of GBS
- 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
Symptoms of GBS
- 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%
What is a clinical diagnosis of GBS evidenced by?
clinical diagnosis evidenced by progressive weakness and areflexia (or hyporeflexia) in the weaker limbs. The Brighton criteria is used for diagnosis.
Primary investigations for GBS
- 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
What are the other investigations to consider
- 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
DDs for GBS
- Transverse myelitis
- Myasthenia gravis
- Lambert-eaton myasthenic syndrome
- Botulism
- Polymyositis
- Vasculitic neuropathy
What is the 1st line management for GBS
- 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
What do you give to patients who are IgA deficient?
CI in IgA deficient patients; allergic reaction