Electrodiagnostic test results in people with a working diagnosis of cubital tunnel syndrome.

Background: Electrodiagnostic tests (EDx) can determine when symptoms and signs suggestive of idiopathic ulnar neuropathy at the elbow (cubital tunnel syndrome; CubTS) is due to measurable ulnar neuropathy at the elbow (UNE), cervical radiculopathy, or median neuropathy at the carpal tunnel, and when there is no measurable neuropathology associated with the symptoms. The role of EDx in management of CubTS is debated. Questions: (1) What is the percentage of patients with CubTS (both including and excluding patients with a previous electrodiagnosis of idiopathic UNE) that have EDx results consistent with idiopathic UNE, other neuropathology, and no detectable neuropathology (2) What factors (e.g. age and gender); are independently associated with electrodiagnosis of UNE. Methods: We retrospectively reviewed all medical records of 133 patients with a working diagnosis of CubTS sent for EDx over a 5-year period in one large urban medical center. We recorded data on patient demographics, comorbidities, non-specialist or specialist referring physician, and EDx results. Results: Among 133 patients, 61% (N = 81) of EDx identified idiopathic UNE, 14% (N = 18) identified other neuropathology, and for 26% (N = 34) there was no measurable neuropathology. Among the 14 patients with a previous ipsilateral or contralateral electrodiagnosis of UNE, all 14 had electrodiagnosis of UNE. Older age and men were independently associated with an increased likelihood of UNE. Conclusions: The observation that people diagnosed with CubTS often do not have UNE, particularly if they are relatively young, suggests that the diagnosis of CubTS may benefit from a more stringent clinical prediction rule. Level of Evidence: Diagnostic; Retrospective cohort study; Level III.