G1 active recording electrode
G1: just anteroinferior to the navicular tuberosity
Place G1 on the medial foot just anteroinferior to the navicular tuberosity over the abductor hallucis.
Table 2 · p.373 ↗
Motor study
Lower limb
Tibial motor nerve conduction study
Place G1 just anteroinferior to the navicular tuberosity; stimulate behind the medial malleolus and proximally in the center of the popliteal fossa.
01 · Placement
G1, G2, stimulation and ground landmarks
G2 reference electrode
G2: just distal and medial to the first MTP joint
Place G2 just distal and medial to the first metatarsophalangeal joint.
Table 2 · p.373 ↗Stimulation site
Ankle stimulation: posterior to the medial malleolus
Stimulate at the ankle posterior to the medial malleolus, 8 cm from G1.
Table 2 · p.373 ↗Stimulation site
Knee stimulation: center of the popliteal fossa
Place the proximal stimulation site in the center of the popliteal fossa.
Table 2 · p.373 ↗Ground region
Ground electrode region
AANEM places the ground between the stimulating and recording electrodes. The model shows a usable posteromedial calf region, not a single mandatory point.
Table 2 · p.373 ↗02 · Reference values
Adult normal limits
| Measure | Reference limit | Basis |
|---|---|---|
| Distal CMAP amplitude | ≥4.4 mV | 3rd percentile lower limit |
| Conduction velocity | ≥39 m/s | 3rd percentile lower limit |
| Distal motor latency | ≤6.1 ms | 97th percentile upper limit |
| Amplitude drop ankle–knee | ≤10.3 mV or 71% | 97th percentile upper limit |
03 · Technique
Acquisition conditions
Fixed distance
G1 to ankle stimulation: 8 cm
Sensitivity
5 mV/div
Sweep
5 ms/div
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 tibial motor reference values recorded from abductor hallucis; see the source table for age- and height-stratified limits.