BILATERAL FAST MAGNETIC-RESONANCE-IMAGING OF THE OPERATED CARPAL-TUNNEL

Our aim was to quantify the structural changes of the carpal tunnel in cluding area and volume after surgical release. We studied 28 patients who underwent 31 operations for carpal tunnel syndrome (CTS), mean ag e 54.7 years (range 32-78). All had abnormal nerve conduction studies. Magnetic resonance imaging (MRI) of both wrists was done before and a fter operation using two fast imaging sequences, turbo spin echo (TSE) and fast field echo (FFE). The same surface coils and parameters were used in both instances. With a computerised analyser we calculated th e volume of the whole tunnel from inlet to outlet before and after ope ration and the wrist volume:carpal tunnel volume ratio. The intensity of the magnetic resonance signal emitted by the median nerve was asses sed in all wrists before and after operation. The mean (SD) volume of the tunnel in 31 wrists with CTS was 11 511.7 (2857) mm(3) before and 13 803.4 (3034.9) mm(3) after operation (p = 0.0001). The mean (SD) re lative signal intensity of the median nerve was 1.7 (1.8) preoperative ly and 1.3 (1.1) postoperatively (p = 0.19). Other postoperative chang es included persistent nerve enlargement (n = 21), misalignment of the tendons (n = 20), fibrous tissue deposits (n = 20), fat tissue deposi ts (n = 21), and muscle oedema (n = 6). The modifications of the carpa l canal as a consequence of open surgical release (including increased volume and displacement of the flexor tendons) argue for the use of a n endoscopic procedure in the treatment of CTS.