Sensitivity was 10–20 μV/division, and the machine used was a TECA model B. Sweep speed, low frequency filter, high-frequency filter, duration of pulse, and rate of pulse were not specified.

This study was performed in the supine position, with the elbow and fingers slightly flexed.

Following the orthodromic method (Figs. 1 and 2), signals were recorded at the wrist (R1) and at the elbow (R2). At the wrist (R1), electrodes were placed between the tendons of the flexor carpi radialis (FCR) and the palmaris longus (PL) muscles (ideally proximal to the distal wrist crease). The active electrode (A) was placed proximally to the distal crease at the wrist, 14 cm proximal to the stimulating cathode. The reference (R) was placed 2 cm proximally to the active electrode [1]. At the elbow (R2), electrodes were placed on the antecubital fossa, just medial to the maximal pulsation of the brachial artery, with a 2–4-cm separation between the proximal cathode (−) and distal anode (+). The authors [1] used a pair of standard 0.6-cm-diameter electroencephalograph electrodes mounted on a plastic block for recording sensory responses. Other routine electrodes (like clips) can be used successfully. In the article, ground (G) electrode was showed on the thenar muscle, but the authors usually placed the ground electrode over the midforearm and on occasion it was placed between the stimulating cathode and the active electrode to diminish a shock artifact, on the palm of the hand.

The median nerve was stimulated 14 cm distally from the wrist to digit II and digit III (S). Each digit was stimulated separately (Figs. 3 and 4). The authors used moistened pipe cleaner for stimulating the sensory fibers of the median nerve. Digit II and digit III: the active stimulating electrode (cathode) was applied at the base of the digit (proximal to the recording site); the anode (+) was positioned slightly distal to the distal interphalangeal joint (distal to the recording site). Supramaximal stimulation was used; stimulus in all determinations was at least 30 % greater than that elicited a maximum response.