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

This study was performed in the supine position, with the subject lying on a comfortable couch with the arm slightly abducted and supported at three or four places by broad webbing straps hung from the beam.

Following the orthodromic method, signals were recorded using surface electrodes (chloride-coated silver plates 16 by 24 mm, held on with adhesive tape and making contact through electrode paste) at the wrist and just above the elbow and on the course of the median nerve (Fig. 1). For recording at the wrist (R), the active (A) electrode was placed proximally to the distal crease at the wrist; the reference (R) electrode was placed proximally to the active electrode [1]. For recording at the elbow (R), the active (A) electrode was placed proximally to the wrist; the reference (R) electrode was placed proximally to the active electrode. Distance between the recording and stimulating electrodes was not fixed. Ground (G) electrode was placed on the dorsum of the hand; the figure shows the ground electrode placed on the forearm.