Directly applied low intensity direct electric current enhances peripheral nerve regeneration in rats

The influence of direct electric stimulation on nerve regeneration was studied in a model of crush injury of the sciatic nerve of rats. Forty-three rats were used and distributed in four groups according to the procedure: (1) intact nerve, inactive circuit; (2) crush injury, inactive circuit; (3) intact nerve, active circuit; (4) crush injury, active circuit. The low intensity continuous current circuit (1 microA) was implanted in the lumbar region, the anode being fixed to the muscles proximally and the cathode below the nerve distally to the lesion site. The Sciatic Functional Index (SFI) was evaluated at weekly intervals for 3 weeks, the sciatic nerve being resected on the 21st day for histologic and morphometric studies. The SFI progressively improved and the average fiber nerve density recovered to a nearly normal value in Group 2 and increased in Group 4 compared with the control groups (1 and 3), but this was accompanied by a decreased average fiber nerve diameter. Both number and diameter of inter and intra-fascicular blood vessels increased in the stimulated nerves. We conclude that low intensity direct electric stimulation enhances nerve regeneration following a controlled nerve crush injury and increases blood supply by increasing number and diameter of vasa nervorum.