Systematic review: hand activity and ultrasound of the median nerve

Background Ultrasound is an established method of viewing the median nerve in the carpal tunnel syndrome (CTS). There is some evidence to suggest that immediate changes may occur in the median nerve before and after hand activity. The evidence for the validity and reliability of ultrasound for testing acute changes in the median nerve has not been systematically reviewed to date. Aims To evaluate the evidence for visible change in ultrasound appearance of the median nerve after hand activity. Methods A literature search was designed, and three reviewers independently selected published research for inclusion. Two reviewers independently appraised papers using the Evidence Based Library and Information Practice (EBLIP) appraisal checklist, while the third reviewer resolved discrepancies between appraisals. Results Ten studies were appraised and the results showed an increase in median nerve cross-sectional area following activity, with a return to normal size within 1 h following activity. Both healthy individuals and those diagnosed with CTS participated, all were small convenience samples. Ultrasonographic measurements of the median nerve were reliable in the four studies reporting this, and the studies demonstrated high quality. Conclusions Good-quality evidence as identified by the EBLIP appraisal checklist suggests that following hand activity, the median nerve changes in size in the carpal tunnel. The results may not be generalizable to all people and activities due to the use of small convenience sampling and narrow range of activities studied, in all of the studies appraised.