GBS Variants:
-AIDP (Acute inflammatory demyelinating polyneuropathy)- 85-95 % of GBS
-Miller Fisher Variant (5 % US but up to 25 % in Japan)
-AMAN (Acute motor axonal neuropathy)
-AMSAN (Acute sensorimotor axonal neuropathy)
Timing:
Acute (<4 weeks)
Pathophysiology:
Due to molecular mimicry from immune response to preceding infection that cross reacts with components of the peripheral nerve.
Diagnostic Criteria:
- Progressive weakness of ≥ 2 limbs due to neuropathy
- Areflexia
- Disease course < 4 weeks
- Exclusion of other causes
Supportive criteria:
- Symmetric weakness
- Mild sensory involvement
- Absence of fever
- Typical CSF profile
- EMG evidence of demylination
Most common infectious triggers:
-Campylobacter Jejuni (most common), CMV, EBV, HIV, VZV, Mycoplasma, and even Zika virus
Most sensitive physical exam findings in GBS
-Absent/Depressed DTR (90 %)
-Ascending extremity weakness (90 %)
-Paresthesias (80 %)
-Dysautonomia (70 %)
-Facial weakness or bulbar signs (55 %)
-Back/extremity pain, respiratory failure, oculomotor weakness
What do you see on LP?
Albumino-cytologic dissociation (normal WBC with high protein)
Miller Fisher variant TRIAD:
-Ophthalmoplegia
-Ataxia
-Areflexia
Antibodies against GQ1b (anti-ganglioside) present in 85-90 % of patients
Treatment
-Supportive treatment
-IVIG
-Plasma Exchange
Remember that steroids are not effective!