In situ ulnar nerve decompression at the cubital tunnel via a small incision with electromyography localization

Abstract

Objective To evaluate the therapeutic effect of in situ ulnar nerve decompression at the cubital tunnel via a small incision assisted with electromyography localization and discuss the surgical indications.Methods Twelve patients who were diagnosed with idiopathic cubital tunnel syndrome (CuTS) without intrinsic muscle atrophy and elbow deformity were involved in the study.Before the operation, short-segment nerve conduction test (SSCT) was carried out.The exact compression site was determined by the ＞ 50%reduction in amplitude or ＞ 0.5 ms lengthening in latency of action potentials recorded upon stimulation of the ulnar nerve around the elbow at 1 cm intervals.An in situ ulnar nerve release at the compression site was performed.Compression of the ulnar nerve was observed and documented to verify the accuracy of pre-operative SSCT localization.Results Intraoperative findings confirmed that lesions were located from 3 cm above to 1 cm below the medial epicondyle, which coincided with the compression sites determined by SSCT.All the patients reported alleviation of hand discomfort postoperatively.Follow-up at 3 months postoperatively showed that paresthesia in the distribution of the ulnar nerve in the hand disappeared.Pinprick sensation recovered.There was no subjective or measurable weakness in pinch or grip strength and no clumsiness or loss of coordination.Claw deformity disappeared.Six months after the surgery, the strength of abductor digiti minimi returned to normal.Two-point discrimination of the little finger was 5.0 mm on average.Nerve conduction velocity returned to ＞ 45.0 m/s.Action potential amplitude increased and SSCT yielded no positive findings.Mild atrophy was reversed one year postoperatively.Elbow flexion test, Tinel' s sign and Froment' s test were all negative.Conclusion In situ ulnar nerve decompression via a small incision assisted with electromyography localization is a suitable procedure for certain CuTS cases. Key words: Cubital tunnel syndrome; Electromyography; Ulnar nerve