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

OBJECTIVE

To 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).

METHODS

In 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.

RESULTS

We 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%.

CONCLUSION

The present study found the highest diagnostic accuracy of SSNCSs (85%), followed by 10-cm NCSs (83%), and of US (77%).

SIGNIFICANCE: US is particularly useful in patients with axonal UNE, while SSNCSs in UNE with conduction block.