Diagnostic accuracy of ultrasonographic and nerve conduction studies in ulnar neuropathy at the elbow

• Diagnostic accuracy of high-resolution ultrasonography (US) is lower than of standard 10-cm nerve conduction studies (NCSs) and of short-segment NCSs (SSNCSs).
• US proved to be particularly useful in patients with axonal ulnar neuropathy at the elbow (UNE), while SSNCSs in UNE with conduction block.
• Use of both SSNCSs and US improves the reliability of the diagnosis of UNE, which is particularly important when surgical therapy is contemplated.

ObjectiveTo report diagnostic accuracy of ultrasonography (US) and compare it to standard 10-cm nerve conduction studies (NCSs), and short-segment NCSs (SSNCSs) across the elbow in the diagnosis of ulnar neuropathy at the elbow (UNE).MethodsIn a broad spectrum of consecutive patients with suspected UNE a prospective and blinded study was performed. This included a clinical examination, electrodiagnostic (EDx) and US studies. In clinically definite UNE patients we compared the sensitivity of SSNCSs, of 10-cm NCSs across the elbow, and of US. The specificity was calculated in asymptomatic controls.ResultsWe studied 113 affected arms in 109 patients; definite UNE was diagnosed in 81, and alternative conditions in 12 arms. The sensitivity of SSNCSs was 89%, of 10-cm NCSs 83%, and of US 71%. We found the highest sensitivity of US in patients with axonal UNE (93%), followed by conduction slowing (82%) and conduction block (55%). Specificity of SSNCSs was 80%, of 10-cm NCSs 82%, and of US 82%.ConclusionThe present study found the highest diagnostic accuracy of SSNCSs (85%), followed by 10-cm NCSs (83%), and of US (77%).SignificanceUS is particularly useful in patients with axonal UNE, while SSNCSs in UNE with conduction block.