There are conflicting hypotheses regarding the initial pathogenesis of carpal tunnel syndrome (CTS). One hypothesis characterizes it as inflammation of the median nerve caused by compression, while another hypothesis characterizes CTS as non-inflammatory fibrosis of the subsynovial connective tissue (SSCT). This study aimed to investigate the differences in the ultrasonography parameters before and after a steroid injection, which is effective for CTS, to elucidate the initial pathogenesis of CTS and the mechanisms of action of the injected steroid. Fourteen hands from 14 healthy participants and 24 hands from 24 participants with mild CTS were examined. Dynamic movement and morphology of the median nerve before and after steroid injection were measured. There was no significant difference in the normalized maximal distance of the median nerve, which reflects the degree of fibrosis in the SSCT indirectly, during finger and wrist movements before and after the injection among patients with CTS (p > 0.05). Among the parameters that indirectly reflects the degree of median nerve compression, such as normalized maximal change in the aspect ratio of the minimum-enclosing rectangle (MER), maximal change in the median nerve perimeter, and maximal value of the median nerve cross-sectional area (CSA), statistically significant differences were not observed between values of the normalized maximal change in the aspect ratio of the MER and maximal change in the median nerve perimeter, during finger and wrist movements recorded before and after the injection in patients with CTS (p > 0.05). However, multivariate logistic regression analysis revealed that the change in the normalized maximal value of the median nerve CSA, according to finger and wrist movement was correlated with the administration of the steroid injection (p < 0.05). In conclusion, compared to that noted before steroid injection, the median nerve CSA noted during finger and wrist movements changed significantly after injection in patients with mild CTS. Given the improvement in median nerve swelling after steroid injection, but no improvement in the movement of the median nerve during finger and wrist movements, median nerve swelling due to compression (rather than fibrosis of the SSCT may be the initial pathogenesis of early-stage (mild) CTS, and the fibrous changes around the median nerves (SSCT) may be indicative of secondary pathology after median nerve compression. Further studies are required to validate the findings of our study and confirm the pathogenesis of CTS.

关于腕管综合征 (CTS) 的初始发病机制存在相互矛盾的假设。一种假设将其表征为由压迫引起的正中神经炎症，而另一种假设将 CTS 表征为滑膜下结缔组织 (SSCT) 的非炎性纤维化。本研究旨在调查对 CTS 有效的类固醇注射前后超声检查参数的差异，以阐明 CTS 的初始发病机制和注射类固醇的作用机制。检查了 14 名健康参与者的 14 只手和 24 名轻度 CTS 参与者的 24 只手。测量类固醇注射前后正中神经的动态运动和形态。正中神经归一化最大距离无显着差异，这间接反映了 CTS 患者注射前后手指和手腕运动过程中 SSCT 的纤维化程度（p > 0.05）。在间接反映正中神经受压程度的参数中，如最小包围矩形（MER）纵横比的归一化最大变化、正中神经周长的最大变化和正中神经横截面的最大值区域（CSA），在 CTS 患者注射前后记录的手指和手腕运动期间，MER 纵横比的归一化最大变化值和正中神经周长的最大变化值之间没有观察到统计学上的显着差异。 p > 0.05）。然而，多变量逻辑回归分析显示，根据手指和手腕运动，正中神经 CSA 标准化最大值的变化与类固醇注射的给药相关（p < 0.05）。总之，与类固醇注射前相比，轻度 CTS 患者在注射后手指和手腕运动过程中注意到的正中神经 CSA 发生了显着变化。鉴于注射类固醇后正中神经肿胀有所改善，但手指和手腕运动时正中神经的运动没有改善，由于压迫（而不是SSCT的纤维化）引起的正中神经肿胀可能是早期的初始发病机制。轻度）CTS，正中神经周围的纤维变化 (SSCT) 可能表明正中神经受压后继发性病变。