Diffusion tensor imaging of the median nerve before and after carpal tunnel release in patients with carpal tunnel syndrome: feasibility study

To evaluate diffusion tensor imaging (DTI) indices of the median nerve pre and postoperatively in patients with carpal tunnel syndrome (CTS) to determine whether indices acquired prior to surgery differ from those acquired postoperatively. Following IRB approval, ten patients with a diagnosis of CTS were prospectively recruited. Eight patients completed the study (seven women, one man). All had bilateral asymmetric symptoms, with subsequent carpal tunnel release on the more symptomatic side. DTI of both wrists were performed using single-shot spin-echo echo-planar imaging (TR/TE, 7,000/103 ms; b value 1,025 s/mm(2)) preoperatively, 6 weeks and 6 months after carpal tunnel release. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the median nerve at the level of the distal radioulnar joint and pisiform were determined by one investigator blinded to clinical data, side, and time relative to surgery. All patients had resolution of symptoms on the surgical side at 6 months. A significant increase in FA (p = 0.018) and decrease in ADC (p = 0.017) were found proximally at 6 months compared to baseline on the operative side. A significant increase in FA was observed on the operative side distally at 6 weeks (p = 0.012) and 6 months (p = 0.017). There was a significant difference in the percentage change in FA values from baseline to 6 months on the operative side in comparison with the non-operative side (p = 0.017). A significant increase in FA and decrease in ADC of the median nerve are seen following decompression surgery in patients with CTS.