Advances in ultrasound technology have made it possible to gain higher spatial resolution and even depict nerves with excellent visual quality. In this article, the literature concerning sonography in the diagnosis of carpal tunnel syndrome (CTS) is critically reviewed. We searched Medline for studies on sonography in the diagnosis of CTS and used the reference lists of the articles found. A total of seven studies on the diagnostic capabilities of sonography was found. There were considerable differences in study design. A reliable diagnosis of CTS could be made sonographically, mainly based on an increase in cross-sectional area of the median nerve at the level of the pisiform or hamate bone. However, most studies could not compare the diagnostic capabilities of sonography to those of electrodiagnostic studies, because the latter was applied as the gold standard. Several other reports on the possible extra value of sonography in CTS are mentioned (mass lesions, anatomical variants, rheumatological diseases, renal dialysis-related amyloidosis, surgery, corticosteroid injection). It is probable that sonography will not replace electrodiagnostic studies, but may serve as an additional investigation. To gain further insight into the possible additional value of sonography, it is necessary to examine subcategories of CTS patients in which electrodiagnostic studies are equivocal.

High-resolution sonography is an accurate and easily applied test for the diagnosis of UNE. The authors recommend its use in addition to electrodiagnostic studies because it improves the reliability of the diagnosis of UNE.

Using ultrasonography we found multiple sites with nerve enlargement along the course of the brachial plexus, median, ulnar, and radial nerves in the majority of 21 patients with multifocal motor neuropathy. Sonography and electrophysiologic studies showed more abnormalities than expected on purely clinical grounds. Moreover, sonography revealed nerve enlargement without clinical or electrophysiologic abnormalities.

The aim of this study was to determine possible correlations between the clinical characteristics, electrophysiological features, and sonographic ulnar-nerve diameter in patients with ulnar neuropathy at the elbow (UNE). We prospectively performed clinical, electrodiagnostic, and sonographic studies in 102 patients having either purely sensory signs (35%) or sensorimotor signs (65%) of UNE. Nerve conduction studies had a sensitivity of 78%, and the addition of sonography increased this to 98%. The diagnostic value of both tests was not different among cases with and without motor deficit. Motor studies with recording from the abductor digiti minimi and first dorsal interosseous muscles were equally sensitive for the detection of conduction block or velocity slowing across the elbow, but the combination yielded more positive cases than when only one study was performed. There were modest negative correlations between the electrodiagnostic parameters and the sonographic ulnar-nerve diameter. Electrodiagnostically and sonographically, there were no significant differences between clinically pure sensory and mixed sensorimotor cases of UNE, except for electrodiagnostic findings suggesting loss of motor axons in cases with motor signs. Almost half the patients with only sensory signs had electromyographic evidence of motor axonal loss. We conclude that, although UNE is clinically heterogeneous, the electrophysiological and sonographic findings are fairly consistent despite the clinical manifestations.