Digital nerve action potentials in healthy subjects, and in carpal tunnel and diabetic patients.

A technique is described for stimulating and recording from nerves in the finger using surface electrodes. A decrease in amplitude and velocity was found with increasing age. In control subjects the digital potential was approximately one and a half times larger than the potential recorded at the wrist. In patients with carpal tunnel syndrome there was some reduction in amplitude and velocity of the digital potential, but the changes were more marked at the wrist. In diabetic patients more uniform changes were found in the two segments. The technique was particularly useful in enabling conduction velocity to be calculated in the digital nerves when no potential could be recorded at the wrist.