The use of ultrasonography in detection of synovitis in carpal tunnel syndrome.

The findings of pre-operative ultrasonography of the carpal tunnel were compared with synovial histology in 50 surgically treated wrists with carpal tunnel syndrome. Eight wrists with a massive hypoechoic area (group 3) had synovitis. 28 with a minimal hypoechoic area (group 1) had no evidence of inflammation. 14 with a moderately increased hypoechoic area (group 2) consisted of three with synovitis, four with lymphocytic infiltration and seven without inflammation. Group 3 strongly indicates synovitis, in which case one should consider aetiology other than the idiopathic cause. Bilateral synovial thickening suggests carpal tunnel syndrome as the initial clinical picture of rheumatoid arthritis, and group 1 indicates idiopathic carpal tunnel syndrome provided that there are no primary causes.