Objective
To assess the median nerve compression with ultrasonography before and after the carpal tunnel release and to assess the correlation between electrophysiologic findings and ultrasonographic findings of the median nerve.

Method
We studied 50 hands of 29 patients diagnosed as carpal tunnel syndrome electrophysiologically and 20 hands of 19 asymptomatic controls. We evaluated the flattening ratio and compression ratio through the short axis and long axis of the median nerve by ultrasonography before carpal tunnel release, 2 weeks and 3 months after release. The correlation of the

improvement between the eletrophysiologic findings and compression ratio was analyzed.

Results
The compression ratio of the median nerve was decreased significantly after carpal tunnel release, compared with that before release. The decrease of the compression ratio correlated with the improvement of the electrophysiologic findings significantly.

Conclusion
The ultrasonography is useful to follow up the median nerve after carpal tunnel release. (J Korean Acad Rehab Med 2002; 26: 172-176)