Precise localization of ulnar neuropathy at the elbow

•Combination of electrodiagnostic and ultrasonographic studies precisely localized ulnar neuropathy at the elbow (UNE) in 93% of arms.•Short segment nerve conduction studies (71%) and ultrasonography (72%) were similarly efficient in precise UNE localization.•Nerve constriction at the site of ulnar nerve entrapment in the cubital tunnel is reported for the first time.

ObjectiveTo report the utility of short-segment nerve conduction studies (SSNCSs) and ultrasonography (US) in the precise localization of ulnar neuropathy at the elbow (UNE) and differentiation between lesions in the retroepicondylar (RTC) groove and under the humeroulnar aponeurotic arcade (HUA; i.e., cubital tunnel).MethodsIn a group of prospectively recruited patients with suspected UNE, four blinded examiners took a history and performed neurologic, electrodiagnostic (EDx) and ultrasonographic (US) examinations. Precise UNE localization was determined by SSNCSs criteria (conduction slowing and conduction block), and by US criteria (changes in cross-sectional area – CSA). Localizations obtained by EDx and US studies were compared.ResultsWe included 83 patients (86 arms) with SSNCSs or US diagnosis of UNE. US confirmed the SSNCSs localization in 45%, provided localization alone in 24%, and was unable to confirm SSNCSs localization in 23% of arms. Lesions in RTC (76%) were mainly demyelinating (63%), and localized at the medial epicondyle (29%) or 2 cm proximal to it (69%). By contrast, lesions at HUA (17%) were mainly axonal (73%), and localized 2 cm (57%) or 3 cm (43%) distal to the medial epicondyle.ConclusionSSNCSs and US are able to precisely localize UNE in the majority (93%) of arms with pathologic SSNCSs or US. UNE in RTC are predominantly demyelinating, and approx. 5-times more common than UNE at HUA that are more commonly axonal.SignificanceSSNCSs and US are of similar utility and complement each other in precise UNE localization.