The reasoning: GBS evolves faster than tests
GBS is an acute immune polyradiculoneuropathy with weakness reaching nadir within 4 weeks. Variants include AIDP, AMAN, AMSAN, Miller Fisher and regional forms. Supportive features are bilateral flaccid weakness, areflexia, pain, mild sensory symptoms, facial/bulbar weakness, autonomic instability and albuminocytologic dissociation; CSF and NCS may be normal early.