Localization of Ulnar Neuropathy at the Elbow by Short Segment Stimulation

ABSTRACT

BACKGROUND AND OBJECTIVES: Local compression of the ulnar nerve occurs most commonly at the elbow and optimal surgical intervention should be directed at the specific site of involvement. This study is designed to localize the more discrete region by using the method of short segment stimulation in ulnar neuropathy at the elbow. METHODS: Thirty seven patients who were diagnosed as entrapment ulnar neuropathy at the elbow by routine nerve conduction studies were investigated. Latency changes and amplitude changes including conduction block were determined by stimulating the ulnar nerve at 2cm intervals across the elbow. Six of these patients had orthopedic surgery after undergoing short segment stimulation studies. RESULT: All patients had significant latency changes(> OR =0.7msec) in specific segments by short segment stimulation and 6 patients of them showed conduction block. The most frequently involved segments were between medial epicondyle and 2cm proximal(20 patients) and between medial epicondyle and 2cm distal(9 patients). Only two patients exhibited significant latency changes between 2 and 4cm distal to the medial epicondyle, suggesting cubital tunnel syndrome. Lesions, as identified by surgery, proved to be accurately predicted by preoperative short segment stimulation in 5 of 6 patients. CONCLUSION: Short segment stimulation studies are helpful in localizing more accurate involved segment in ulnar neuropathy at the elbow. And the most commonly involved site is within 2cm of the medial epicondyle suggesting tardy ulnar nerve palsy.