Ulnar neuropathy at the elbow: how frequent is the idiopathic form? An ultrasonographic study in a cohort of patients

Ulnar neuropathy at the elbow (UNE) is the second most frequent focal neuropathy of the arm. The aim of our study was to establish the frequency of anatomical changes of the cubital tunnel capable of causing UNE. Ninety-one consecutive patients affected by UNE, as established by neurophysiological studies, were enrolled in the study. All patients underwent ultrasonographic examination of the elbow, paying particular attention to the cubital tunnel, which was studied with either static or dynamic scans. Fifty-four of the 91 patients (59.3%) had at least one anatomical alteration of the cubital tunnel. The changes observed in our patients were: subluxation of the ulnar nerve (18.7%), luxation of the ulnar nerve (9.9%), presence of osteophytes (6.6%), presence of accessory muscle (8.8%), articular ganglion (1.1%), post-traumatic lesions (3.3%), presence of osseous fragment (1.1%). A possible cause of ulnar nerve entrapment at the elbow was found in more than half of the patients. Joint ultrasonography is indispensable for the identification of such alterations as it allows for both static and dynamic evaluation of the ulnar nerve.