| Conduction velocity in m/s | Distal latency (ms) | Temporal dispersion | Conduction block | F wave latency (ms) | |
| Set 1 must have one abnormality in two nerves | <95% if amp >50%; <85% if amp <50% | >110% if amp normal; >120% if amp <normal | Prox-dist duration increase 30% or | Prox-dist amp ratio <0.7 | >120% |
| Set 2 must have 3 abnormalities | <80% if amp >80%; <70% if amp <80% (2 nerves) | >125% if amp >80%; >150% if amp <80% (2 nerves) | >20% NP amp or NP area decrease prox-dist; >15% prox-dist duration increase (one or more nerves) or | >20% NP amp or NP area decrease prox-dist (one or more nerves) | >120% if amp >80%; >150% if amp <80% (2 nerves) |
| Set 3 must have one abnormality in 2 nerves | <90% if amp >50%; <85% if amp <50% | >110% if amp normal; >120% if amp <normal | Prox-dist dur increase 30% | >120% | |
| Set 4 must have one in 2 nerves | <70% | >150% | Dist-prox dur ratio >150% upper limit of normal; distal dur >300% upper limit of normal | Amp decrease >upper limit of normal | >150% |
| Set 5 must have 2 abnormalities | <80% if amp >80%; <70% if amp <80% (2 nerves) | >125% if amp >80%; >150% if amp <80% (2 nerves) | Prox-dist dur increase 30% | Prox-dist amp ratio <0.7 | >120% if amp >80%; >150% if amp <80% (2 nerves) |
| Set 6 must have 3 abnormalities | <90% if amp >50%; <80% if amp <50% (2 nerves) | >115% if amp normal; >125% if amp <normal (2 nerves) | Prox-dist dur increase 30% (one or more nerves) or | Prox-dist amp ratio <0.7 (one or more nerves) | >125% (one or more nerves) |
Set 1, Albers and colleagues2; set 2, Cornblath3; set 3, Ho and colleagues4; set 4, Dutch GBS study group5; set 5, Italian GBS study group6; set 6, Albers and Kelly.7
amp, compound muscle action potential amplitude; dist, distal; dur, duration; NP, negative peak; prox, proximal.