The machine used was a Medelec MS92a electromyograph. Sensitivity, low-frequency filter, high-frequency filter, sweep speed, duration of pulse, and rate of pulse were not specified.

This study was performed in the supine position.

Following the antidromic method [1], the surface electrodes were placed over digit II (index finger) and over digit I (thumb) to record the median (R1) and superficial radial (R2) sensory nerve action potentials (SNAPs), respectively (Fig. 1). For the median nerve recording (R1), the electrodes were placed at 14 cm distance from the stimulating electrodes at the wrist. Exact active (A) and reference (R) electrode positions were not specified in the text. For the superficial radial nerve recording (R2), the electrodes were placed over the skin of the dorsal hand between the first and second metacarpal areas at a 10 cm distance from the stimulating electrodes at the wrist. The ground (G) electrode position was not specified in the report; the figure shows the ground electrode placed on the palm. Median (R1) and radial (R2) nerve recordings were made separately.

The stimulation was applied at the wrist, 14 cm proximally to the recording electrode (A) on the median nerve (S1) and 10 cm proximally to the recording electrode (A) on the radial nerve (S2). The median nerve (S1) was stimulated proximally to the wrist crease; the superficial radial nerve (S2) was stimulated on the dorsolateral surface of the wrist. Median and radial nerves were stimulated separately.

Peak latency (ms) was measured from the onset of the stimulus to the peak of the negative deflection of the SNAP. Skin temperature was not given. Normal values were recorded from 100 hands of 50 normal subjects (Table 1), 39–78 % women and 11–22 % men (age range 20–42 years, mean age 28.7–27.9 years for women and 31.5 years for men). Pathological values were obtained from 50 patients (Table 2) with carpal tunnel syndrome (CTS), 41–82 % women and 9–18 % men (age range 27–59 years, mean age 38.6–36.7 years for women and 47.1 years for men).