American Academy of Neurology electrodiagnostic criteria for chronic inflammatory demyelinating polyneuropathy8
| At least three of the following four to be fulfilled: |
| 1. Significant reduction in motor nerve conduction velocity in two or more motor nerves: |
| a. <80% of LLN if CMAP >80% of LLN |
| b. <70% of LLN if CMAP <80% of LLN |
| 2. Partial conduction block or abnormal temporal dispersion in one or more motor nerves: either peroneal nerve between ankle and below fibular head, median nerve between wrist and elbow, or ulnar nerve between wrist and below elbow. |
| Criteria suggestive of partial conduction block: <15% change in duration between proximal and distal sites and >20% drop in negative peak (–p) area or peak-to-peak (p-p) amplitude between proximal and distal sites. |
| Criteria for abnormal temporal dispersion and possible conduction block: >15% change in duration between proximal and distal sites and >20% drop in –p area or p-p amplitude between proximal and distal sites |
| 3. Significant prolongation of distal motor latency in two or more motor nerves: |
| a. >125% of ULN if CMAP >80% of LLN |
| b. >150% of ULN if CMAP <80% of LLN |
| 4. Significant prolongation or absence of F-waves in two or more motor nerves: |
| a. >120% of ULN if CMAP >80% of LLN |
| b. >150% of ULN if CMAP <80% of LLN |
CMAP, compound muscle action potential; LLN, lower limit of normal; ULN, upper limit of normal.