G1 active recording electrode
G1: posteroinferior to the lateral malleolus
Place G1 just posterior and inferior to the lateral malleolus over the sural nerve in the groove between the malleolus and Achilles tendon.
Table 2 · p.373 ↗
Sensory study
Lower limb
Sural sensory nerve conduction study
Place G1 posteroinferior to the lateral malleolus and stimulate distally from the midline or slightly lateral calf.
01 · Placement
G1, G2, stimulation and ground landmarks
G2 reference electrode
G2: 3 cm distal bar electrode
Place G2 3 cm distal to G1 along the lateral border of the foot.
Distance · 3 cm distal to G1
Table 2 · p.373 ↗Stimulation site
Stimulation: midline or slightly lateral calf
Stimulate at the mid-calf on or slightly lateral to the posterior midline, 14 cm proximal to G1; orient the cathode distally.
Distance · 14 cm from G1
Table 2 · p.373 ↗Ground region
Ground electrode region
Place the ground on the posterolateral calf between the mid-calf stimulation site and lateral-malleolar recording electrodes.
Table 2 · p.373 ↗02 · Reference values
Adult normal limits
| Measure | Reference limit | Basis |
|---|---|---|
| SNAP onset-to-peak | ≥4 µV | 3rd percentile lower limit |
| SNAP peak-to-peak | ≥4 µV | 3rd percentile lower limit |
| Onset latency | ≤3.6 ms | 97th percentile upper limit |
| Peak latency | ≤4.5 ms | 97th percentile upper limit |
| Conduction velocity | ≥40 m/s | Published 3rd percentile |
03 · Technique
Acquisition conditions
Fixed distance
G1 to stimulation site: 14 cm
Sensitivity
2–5 µV/div
Filter
20 Hz–2 kHz
Sweep
1 ms/div
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 antidromic sural sensory reference values.