Ultrastructural study of peripheral nerve injury induced by monopolar and bipolar diathermy.

The effect of unipolar and bipolar electrocoagulation on human and albino rat peripheral nerves was examined by transmission electron microscopy. The greater auricular nerve obtained from operated patients and the femoral nerve of an albino rat were chosen for this study. The nerves were divided into three groups: controls, segments of nerves spot-coagulated with unipolar instruments, and segments of nerves spot-coagulated with bipolar instruments. Significant cell injury, expressed by marked damage of the Schwann cells, was induced by unipolar coagulation in both myelinated and unmyelinated nerves, in humans as well as in the albino rat. However, in bipolar-treated nerves, the Schwann cell architecture remained well preserved in both types of nerves. The results are in favor of bipolar electrocoagulation when applied in areas rich in neurovascular supplies.