Nerve conduction studies from a 63-year-old man with Guillain–Barré syndrome*
| Sites | Latency, ms | Amplitude, mV | Negative area, ms*mV | Minimum F-wave latency, ms | Distance, cm | CV, m/s |
|---|---|---|---|---|---|---|
| Motor sites | ||||||
| Left median (APB) | ||||||
| Wrist | 14.9 | 2.3 | 13.7 | NR | 7 | |
| Elbow | 20.4 | 1.67 | 11.5 | 23 | 42 | |
| Left ulnar (ADM) | ||||||
| Wrist | 3.6 | 6.4 | 23.5 | 37.6 | 6 | |
| Below elbow | 8.3 | 5.0 | 21.8 | 27 | 57 | |
| Above elbow | 11.4 | 4.8 | 21.5 | 11 | 35 | |
| Left radial (EIP) | ||||||
| Forearm | 2.9 | 5.4 | 26.9 | 8 | ||
| Upper arm | 8.9 | 3.8 | 17.9 | 26 | 43 | |
| Axilla | 9.1 | 2.1 | 10.2 | - | - | |
| Wrist | NR | |||||
| Left fibular (EDB) | ||||||
| Ankle | NR | NR | NR | 9 | ||
| Left fibular (tibial anterior) | ||||||
| Fibular head | 4.5 | 3.8 | 24.4 | - | ||
| Popliteal fossa | 7.5 | 3.8 | - | 10 | 33 | |
| Left tibial (AHB) | ||||||
| Ankle | NR | NR | NR | - | ||
| Left facial (nasalis) | ||||||
| Mastoid | 5.4 | 0.63 | 3.0 | |||
| Onset latency, ms | Peak latency, ms | Amplitude of onset potential, μV | Negative area, ms*μV | Distance, cm | CV, m/s | |
| Sensory sites | ||||||
| Left median | ||||||
| Wrist-digit II | NR | NR | NR | NR | 14 | NR |
| Left ulnar | ||||||
| Wrist-digit V | NR | NR | NR | NR | 12 | NR |
| Left sural | ||||||
| Calf-latency mall | NR | NR | NR | NR | 14 | NR |
| Left superficial peroneal | ||||||
| 12 cm AMM | NR | NR | NR | NR | 12 | NR |
Note: ADM = abductor digiti minimi, AHB = abductor hallucis brevis, AMM = anterior medial malleolar, APB = abductor pollicis brevis, CV = conduction velocity, EDB = extensor digitorum brevis, EIP = extensor indicis proprius, NR = no response.
↵* Latency is the time it takes for the impulse to generate a response. In demyelination, this is prolonged, as shown in the latency times for the wrist (normal < 2.2 ms) and elbow (normal < 4.4 ms) of the left median APB, and at the wrist of the left ulnar ADM (normal < 2.2 ms). F-wave is a measure of motor conduction time of the entire nerve. In demyelination, this is prolonged, as shown in the left ulnar ADM.