Validity and reliability of nerve and muscle ultrasound.

INTRODUCTION: Nerve and muscle ultrasound has been studied in several conditions, but validity and reliability have not been assessed systematically. METHODS: Nerve cross-sectional area and muscle thickness were measured ultrasonographically at several sites in 4 cadavers, which were then dissected, and actual measurements were obtained. To assess intrarater and interrater reliability, between 3 and 5 ultrasonographers, with varying experience levels, made repeated measurements on healthy volunteers. RESULTS: Correlation coefficients for nerve and muscle validity were >0.968 (P < 0.001), and for intrarater reliability were >0.901 (P < 0.001) for still and real-time images. Correlation coefficients for interrater reliability were more varied, but for still images they were all significant at the P < 0.001 (0.542-0.998) level, and for real-time images they were significant at the P < 0.05 level for half the sites (0.243-0.981). CONCLUSION: Overall, nerve and muscle ultrasound is a valid and reliable diagnostic imaging technique.

Median nerve changes following steroid injection for carpal tunnel syndrome.

INTRODUCTION: Neuromuscular ultrasound is a painless, radiation-free, high-resolution imaging modality for assessment of the peripheral nervous system. The purpose of this study was to use neuromuscular ultrasound to assess the changes that occur in the median nerve after steroid injection for carpal tunnel syndrome (CTS). METHODS: Ultrasound and nerve conduction studies were performed at baseline and 1 week, 1 month, and 6 months after steroid injection in 19 individuals (29 wrists) with CTS. RESULTS: Significant changes were noted in median nerve cross-sectional area (P < 0.001), mobility (P = 0.001), and vascularity (P = 0.042) at the distal wrist crease after steroid injection, and the nerve cross-sectional area correlated with symptom score and electrodiagnostic parameters. Changes in the ultrasonographic parameters were seen within 1 week of injection. CONCLUSIONS: These findings suggest neuromuscular ultrasound is potentially helpful for the assessment of individuals undergoing treatment for CTS, as typical changes can be expected after successful treatment injection.