MR-IMAGING OF THE CARPAL-TUNNEL

Objective: Investigations were conducted regarding changes of carpal t unnel shape during wrist motion and the variations of space for the me dian nerve as well as the preoperative signs of carpal tunnel syndrome (CTS) and the postoperative restitution. Methods: Axial MR images (1. 0 T) were performed at the level of the distal radioulnar joint, pisif orme bone and hook of hamate level of 20 wrists of patients with clini cal symptoms of CTS and further 20 wrists of volunteers. This was cond ucted with the wrist in neutral postion, 45 degrees extension and 45 d egrees flexion. T2-weighted signal intensity of the median nerve were measured in 18 patients pre-and postoperatively. Results: The increase of the cross-sectional area of the median nerve at the pisiform level and the flattening of the median nerve at the hook of hamate level as well as the volar bowing of the flexor retinaculum al the pisiform an d hook of hamate level were significantly greater in patients with CTS than in those with normal wrists (P < 0.05-0.001). In postoperative f ollow-up studies the distal flattening of the median nerve recovered i n 94%. The signal intensity of the median nerve on T2-weighted images decreased in 67%. Conclusion: Flexion at the pisiform and hamate level as well as extension at the pisiform level narrows the space availabl e for the median nerve potential leading to compression of the median nerve. MR imaging is accurate and reliable for diagnosis and postopera tive follow-up of CTS. (C) 1997 Elsevier Science Ireland Ltd.