Hypothesis: Does magnetic resonance (MR) neurography parameters predict or correlate with clinical recovery in severe carpal tunnel syndrome (CTS). Methods: Subjects were prospectively collected 22 hands from 22 CTS patients, with abductor pollicis brevis-compound muscle action potential (APB-CMAP) of 2 mV or less and evaluated preoperatively and postoperatively for clinical, electrophysiological, and MR neurography findings to find out potential risk factors and predictors of thumb opposition recovery. Parameters observed in MR neurography were morphological changes in median and thenar branch of median nerve, median nerve diameter and width, carpal tunnel diameter, denervation edema, and bowing ratio. We considered more than 0.5 mV improvement in APB-CMAP postoperatively significant. Results: Two groups were made and compared for all postoperative variables. Group 1 had patients with less than 0.5 mV improvement and group 2 had more than 0.5 mV improvement. Demographic, MR neurogram variables, and functional score had better results in group 2 comparing with group 1 but were not statistically significant. Thumb opposition showed poor results in group 2 comparing with group 1 may be because clinical recovery lags electrophysiological recovery. We did not find any significant difference for duration of symptoms in 2 groups. Conclusion: In practical terms, we did not find any predictor in clinical and MR neurography variables that correlate with recovery of thumb opposition.
