A miniaturized cuff electrode for electrical stimulation of peripheral nerves in the freely moving rat

A bipolar cuff electrode for electrical stimulation of small diameter peripheral nerves is described. The cuff is made of a highly flexible rubber-impression material, and the electrode assembly is suited for chronic implantation. Its manual construction is easy and reliable, utilizing only simple tools. The cuff completely envelopes nerves of varying diameter and requires a minimal amount of manipulations of the nerve, thereby reducing the chance of surgical trauma. The snug envelope prevents the nerve from drying, and minimizes shunting between the two leads by extracellular fluids. Small outer dimensions were achieved: 1.4 x 1.1 x 2.3 mm (width x height x length) when used with nerves of 1 mm diameter, which minimizes pressure and damage to surrounding tissues. Morphometric analysis of nerves enclosed in cuffs for 28-30 h revealed a small decrease in the number of large-diameter fibers. Stimulation thresholds remained, however, constant throughout the experiments.