gms | German Medical Science

Objectives/Interrogation: Cubital tunnel decompression is usually performed to address symptoms of ulnar nerve compression at the elbow. Nerve conduction studies (NCS) are commonly obtained to confirm compression neuropathy prior to scheduling surgery; in a small percentage of cases, surgery is performed despite normal NCS results based on clinical symptoms and signs. Percussion irritability of the nerve, referred to as Tinel's sign, is a common physical finding taken to confirm nerve irritability at a particular site. The aim of this study was to evaluate the presence and site of this sign for the ulnar nerve preoperatively, and to correlate this with the intraoperative site of compression.

Methods: The notes and NCS results of patients undergoing cubital tunnel decompression with or without anterior subcutaneous nerve transposition were reviewed pre-operatively and compared to the surgical findings recorded by an independent observer, masked to the pre-operative results; the surgical site of compression was then correlated with the site of a Tinel sign, if this was present, and NCS findings. Patients who had nerve decompression as part of a bigger reconstructive procedure were excluded.

Results and Conclusions: Thirty-eight cases were identified between June 2017 and September 2018. 92% of patients had a Tinel sign. This was distal to the medial epicondyle in 17 cases, with intra-operative nerve compression noted beneath the humeroulnar aponeurotic arcade between the tendinous attachment of the two heads of flexor carpi ulnaris. The Tinel sign was posterior/proximal to the medial epicondyle in the remaining 21 cases, with intra-operative nerve compression in the retroepicondylar groove in 12 cases, and evidence of compression at both these sites in the other 9 cases. In cases were no Tinel sign was present, compression was identified in the retroepicondylar groove. Hour glass deformity and change in nerve texture with visible and palpable nerve thickening was not present in the absence of a Tinel sign. There were no cases of more proximal nerve compression.

The Tinel sign is a useful adjunct to NCS that can be used to plan surgical approaches as it correlates with the site of nerve compression when this is caused by a defined structure. In cases where nerve compression occurs over longer segments or at multiple sites, this sign is only present consistently at the more proximal site of compression. Therefore, in patients who have this sign distal to the epicondyle, a more limited approach can be safely considered.