CARPAL-TUNNEL SYNDROME - CORRELATION OF MAGNETIC-RESONANCE-IMAGING, CLINICAL, ELECTRODIAGNOSTIC, AND INTRAOPERATIVE FINDINGS

WE UNDERTOOK A prospective study of 43 wrists in 32 patients who had b een clinically diagnosed as having carpal tunnel syndrome (study group ) and 5 wrists in people who had no symptoms (control group), correlat ing the clinical, electrodiagnostic, intraoperative, and magnetic reso nance imaging (MRI) findings. MRI of the carpal tunnel and thenar emin ence was performed, using coronal and axial T1- and T2-weighted, proto n density, and short tau inversion recovery sequences. Abnormalities o f the median nerve, as revealed by MRI, were found in 43 of 43 (100%) wrists in the study group and in 0 of 5 (0%) wrists in the control gro up. Increased signal of the median nerve was seen in 41 of 43 (95%) wr ists, increased signal of the flexor tendon sheath in 41 of 43 (95%), volar bowing of the flexor retinaculum in 39 of 43 (91%), increased di stance between the flexor tendons in 37 of 43 (86%), and abnormal nerv e configuration in 28 of 43 (65%). Increased short tau inversion recov ery signal of the thenar muscles was found in 5 of 43 (12%) wrists, al l of which had undergone severe denervation changes, as revealed by el ectromyography. Operative release was performed for 27 of 43 (63%) wri sts, and follow-up was obtained for 42 of 43 (98%). A good or excellen t postoperative outcome resulted for 20 of 27 (74%) patients, a fair o utcome for 2 of 27 (7%), and a poor outcome for 4 of 27 (15%), and 1 o f 27 (4%) patients was lost to follow-up. For patients undergoing carp al tunnel release whose MRI revealed an abnormal nerve configuration, the outcome was improved, with good or excellent results in 15 of 18 ( 83%) patients. No association with outcome was seen with median nerve or flexor tendon signal changes, increased interspace between the flex or tendons, or flexor retinaculum bowing. Our results indicate that MR I is a sensitive diagnostic modality that can demonstrate signal and c onfigurational abnormalities of the median nerve in patients diagnosed with carpal tunnel syndrome. Increased signal of the thenar muscles, as revealed by MRI, using short tau inversion recovery sequences, occu rs only in muscles that have undergone severe denervation changes, as revealed by electromyography.