Table 1 Diagnosis of GBS

Features required for diagnosis

 Progressive weakness in both arms and legs (might start with weakness only in the legs)

 Areflexia (or decreased tendon reflexes)

Features that strongly support diagnosis

 Progression of symptoms over days to 4 weeks

 Relative symmetry of symptoms

 Mild sensory symptoms or signs

 Cranial nerve involvement, especially bilateral weakness of facial muscles

 Autonomic dysfunction Pain (often present)

 High concentration of protein in CSF

 Typical electrodiagnostic features

AMAN

 None of the features of AIDP except one demyelinating feature allowed in one nerve if dCMAP <10% LLN

 Sensory action potential amplitudes normal

AMSAN

 None of the features of AIDP except one demyelinating feature allowed in one nerve if dCMAP < 10% LLN

 Sensory action potential amplitudes < LLN