G1 active recording electrode
G1: center of the EDB
Place G1 over the center of the EDB muscle belly on the dorsolateral foot, adjusting to obtain an initial negative CMAP deflection.
Table 2 · p.373 ↗
Motor study
Lower limb
Fibular (peroneal) motor nerve conduction study
Place G1 over the center of EDB and stimulate sequentially at the ankle, below the fibular head and above the fibular head.
01 · Placement
G1, G2, stimulation and ground landmarks
G2 reference electrode
G2: distal to the fifth MTP joint
Place G2 just distal to the fifth MTP joint over the distal EDB tendon, completely off the muscle belly.
Table 2 · p.373 ↗Stimulation site
Ankle stimulation: lateral to the tibialis anterior tendon
Stimulate at the anterior ankle 8 cm proximal to G1, immediately lateral to the tibialis anterior tendon; orient the cathode distally.
Distance · 8 cm from G1
Table 2 · p.373 ↗Stimulation site
Below fibular head: posteroinferior
Stimulate the common fibular nerve posteroinferior to the fibular head where it approaches the fibular neck.
Distance · Variable—measure the S1–S2 segment on the patient
Table 2 · p.373 ↗Stimulation site
Above fibular head: 10 cm proximal
Stimulate about 10 cm proximal to S2, just medial to the biceps femoris tendon at the lateral popliteal fossa.
Distance · 10 cm proximal to S2
Table 2 · p.373 ↗Optional accessory fibular study
Optional accessory fibular stimulation: behind lateral malleolus
For the optional accessory fibular study, stimulate just posterior to the lateral malleolus while continuing to record from EDB; a reproducible CMAP supports an accessory branch.
Distance · Variable—stimulate just posterior to the lateral malleolus
Accessory fibular nerve technique · p.25 ↗Ground region
Ground electrode region
Place the ground on the anterolateral lower leg between the ankle stimulation site and the proximal fibular-head sites.
Table 2 · p.373 ↗02 · Reference values
Adult normal limits
| Measure | Reference limit | Basis |
|---|---|---|
| Distal CMAP amplitude | ≥1.3 mV | 3rd percentile lower limit |
| CV ankle–below head | ≥38 m/s | 3rd percentile lower limit |
| CV across fibular head | ≥42 m/s | 3rd percentile lower limit |
| Distal motor latency | ≤6.5 ms | 97th percentile upper limit |
| Amplitude drop across head | ≤25% | 97th percentile upper limit |
| CV drop across head | ≤6 m/s or 12% | 97th percentile upper limit |
03 · Technique
Acquisition conditions
Fixed distance
G1 to ankle: 8 cm; across-fibular-head segment: 10 cm; accessory site is anatomical
Sensitivity
5 mV/div
Sweep
5 ms/div
Limb position
S4 is optional when an accessory fibular response is suspected
Filter
2–3 Hz–10 kHz
Temperature
Maintain dorsal foot skin temperature >31°C
Ground
Place the ground between the stimulating and recording electrodes
Primary evidence
Method-matched AANEM reference data
Adult fibular motor reference values recorded from EDB; see the source table for age- and height-stratified limits.