Guillain-Barre syndrome Flashcards
Define Guillain Barre Syndrome.
Acute immune-mediated demyelinating peripheral poly-neuropathy.
How common is Guillain Barre syndrome?
- 1 in 100 000/yr.
- ?Male predominance
- ?More during summer
What is the aetiology of GBS?
- Usually within 6 weeks of upper tract respiratory infection or gastroenteritis
- In 40%, no cause is found
- Most common triggers:
- Campylobacter jejuni (60-70%)
- Mycoplasma species
- CMV
- EMB
- Mycoplasma pneumonia
- Immunisations e.g. swine flu vaccine (1976) and rabies vaccine
- Zika virus, dengue, chikungunya, Japanese encephalitis
Summarise the pathophysiology of GBS.
- Antecedent infection making antibodies
- -→ cross-reaction of antibodies with gangliosides in the PNS
- -→ immune attack on myelin sheath or Schwann cells of sensory/motor nerves
- -→ may advance quickly, affecting all limbs; progressive phase of up to 4 weeks, followed by recovery.
Unlike other neuropathies, proximal muscles are more affected, eg trunk, respiratory, and cranial nerves (esp. vii).
Pain is common (eg back, limb) but sensory signs may be absent.
What are the risk factors for Guillain Barre syndrome?
- Preceding viral illness
- Precding bacterial infection - C jejuni especially
- Preceding mosquito-borne viral infection - Zika, CMV, dengue
- Hep E infection
- Immunisation e.g. eight cases of GBS occurred after meningococcal conjugate vaccine A, C, Y, and W135 (MCV4)
- Cancer/lymphoma
- Old age (mean 40yrs)
- Male
- HIV infection
What is Miller-Fisher syndrome?
Miller-Fisher syndrome: ophthalmoplegia, ataxia, and areflexia
(also referred to as Fisher’s syndrome).
Subtype of motor variant of Guillain Barre
What are the symptoms of GBS?
- A few weeks after an infection, symmetrical ascending muscle weakness begins.
- Respiratory distress - dyspnoea on exertion and SOB
- Slurred speech (facial weakness and oropharyngeal weakness)
- Paraesthesia
- Back/leg pain
- Facial weakness
- Swallowing difficulty
- Extra-ocular muscle weakness
- Diplopia
- Dysarthria
- Dysphagia
- Dysautonomia - sinus tachycardia, HTN, and postural hypotension in two thirds of GBS
What is the cause of swallowing difficulty in GBS?
bulbar dysfunction causing oropharyngeal weakness –> swallowing difficulty
What is a common initial symptom of GBS?
around 65% of patients experience back/leg pain in the initial stages of the illness
What are the signs of GBS on examination?
- Muscle weakness
- Respiratory distress
- Mild sensory abnormalities
- Areflexia/hyporeflexia
- Flaccid tone
- Plantars downgoing or absent
- Facial droop
- Ptosis
- Altered GCS
- Other: non reactive pupils, ophthalmoplegia, anisocoria (difference of 0.4mm between pupil sizes), papilloedema (thought to be secondary to reduced CSF resorption)
Describe the pattern of muscle weakness in GBS.
- Weakness affects legs then arms, and proximal before distal muscles
- Paraesthesias in hands and feet frequently precede the onset of weakness
- Paralysis is FLACCID with areflexia
- Progresses acutely over days with 50% reaching lowest point by a week and 98% by 4 weeks
What investigations would you do for GBS?
MAIN:
CT then LP → rise in protein with normal WCC (albuminocytologic dissociation) found in 65% of GBS
Nerve conduction studies -→ decreased motor velocity (from demyelination), long distal motor latency, increased F wave latency
BUT diagnosis made by pattern recognition.
OTHER:
Bedside:
- LFTs - AST, ALT, bili elevated
- Spirometry - reduced FVC. Ventilate if FVC <1.5L, PaO2<10kPa, PaCO2>6kPa.
- Antiganglioside antibodies
- Serology - Campylobacter jejuni, CMV, EBV, Mycoplasma pneumoniae, or Haemophilus influenzae
Imaging:
- Nerve conduction studies - slowing velocities
- Spinal MRI - may show enhancement of cauda equina nerve roots with gadolinium
Invasive:
- LP - CSF proteins raised (>5.5g/L), normal WCC
What is the prognosis with GBS?
- Good; ~85% make a complete or near-complete recovery at 6months-1yr.
- 10% are unable to walk alone at 1yr.
- Complete paralysis is compatible with complete recovery.
List some autonomic disturbances which occur in GBS.
- Sinus tachycardia
- Labile BP
- Postural hypotension
- Urinary retention
- Ileus
- Cardiac arrhythmia (rarely)
What is the most sensitive way to readily assess if there is neuromuscular respiratory compromise?
What type of respiratory failure occurs in GBS?
Spirometry
Type 2 respiratory failure, with pCO2 rising early and pO2 falling later.
What are some causes of predominantly sensory vs predominantly motor neuropathies?
