Minimally invasive endoscopic ulnar nerve assessment and surgery for cubital tunnel syndrome patients—Relation between endoscopic nerve findings and clinical symptoms

To minimize damage to healthy tissues, we have been performing endoscopically assisted cubital tunnel syndrome surgery based on endoscopic nerve findings since 1995. This is the first study to focus on endoscopic surgery for cubital tunnel syndrome based on endoscopic ulnar nerve findings and the subsequent postoperative clinical results. We analysed 82 upper extremities of 74 cubital tunnel syndrome patients who had undergone endoscopically assisted release surgery using the Universal Subcutaneous Endoscope system. Endoscopic observations of the ulnar nerve were made from a single 1- to 3-cm endoscopic portal incision at the cubital tunnel to 10 cm proximal and 10 cm distal. The abnormal nerve areas were identified and released based on nerve degeneration findings under endoscopic observation. The abnormal areas spread eccentrically from the entrapment point(s). In 82 diseased upper extremities, ulnar nerve entrapment occurred at the cubital tunnel. However, one extremity suffered from entrapment at the arcade of Struthers' in addition to the cubital tunnel. All patients showed improved clinical symptoms following surgery. There is no statistical relation between pre- and postoperative clinical scores of Dellon's Staging and abnormal nerve length findings. Cubital tunnel syndrome is usually caused by entrapment at the cubital tunnel; however, in some cases, there are other point entrapment(s). Our endoscopically assisted procedure avoids any damage to healthy tissues because the surgeon can observe the entrapment point(s) prior to release. Postoperative clinical recovery results clearly indicate that endoscopic nerve findings reveal entrapment points and ulnar nerve degeneration can spread maximally 10 cm distally and proximally from the entrapment point(s), even in clinically mild severity cases. All other possible entrapment points should, therefore, be observed and released using our procedure.