28/11/2022
Median Nerve Mobility in Patients with Carpal Tunnel Syndrome
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👉 Carpal tunnel syndrome (CTS) is a common entrapment neuropathy causing disturbing symptoms including pain numbness, and tingling sensation. Furthermore, more severe CTS could decrease grip strength, impair working ability and affect life quality. https://pubmed.ncbi.nlm.nih.gov/27751557/
👉 Recently, increasing numbers of researchers have provided data that the excursion of the median nerve (MN) [https://pubmed.ncbi.nlm.nih.gov/12954253/, https://pubmed.ncbi.nlm.nih.gov/25640903/, https://pubmed.ncbi.nlm.nih.gov/24594417/, https://pubmed.ncbi.nlm.nih.gov/34679591/, https://pubmed.ncbi.nlm.nih.gov/32644200/] and tendon excursion [https://pubmed.ncbi.nlm.nih.gov/22606333/] were reduced during finger movement in patients with CTS compared to healthy people, possibly related to the interaction between the nerve, tendon and subsynovial connective tissue [https://pubmed.ncbi.nlm.nih.gov/24038546/].
👉 Thus, reduced displacement of the MN in CTS patients could potentially be developed as a marker for diagnosing CTS or evaluating the treatment efficacy for CTS.
👉 Lin et al conducted a meta-analysis to quantify the excursion of the MN in patients with CTS compared to healthy individuals under dynamic ultrasound investigation. https://pubmed.ncbi.nlm.nih.gov/36394604/
They included 14 studies involving a total of 375 CTS patients and 296 healthy controls. Compared to healthy controls patiens with CTS exhibited a large reduction in transverse and longitudinal nerve excursion (SMD = −1.47, 95% CI: −1.91, −1.03).
👉 In CTS patients, the Subsynovial connective tissue (SSCT) might develop fibrotic changes and affect tendon mechanics [https://pubmed.ncbi.nlm.nih.gov/17953971/], leading to poor compliance with gliding, elongation, and deformation [https://pubmed.ncbi.nlm.nih.gov/29108853/]. Normally, the gliding unit contains finger flexor tendons and SSCT [https://pubmed.ncbi.nlm.nih.gov/20537576/]. However,repetitive, high force or high-velocity movement of the tendon might induce damage to SSCT, resulting in SSCT-tendon disrupted [https://pubmed.ncbi.nlm.nih.gov/17953971/].
👉 A stiffer and thicker SSCT might also increase intra-carpal tunnel pressure, followed by nerve ischemia and compression, impairing the motion of the MN. https://pubmed.ncbi.nlm.nih.gov/29108853/
👉 Several studies showed a relationship between MN mobility, the severity of CTS, and associated parameters [https://pubmed.ncbi.nlm.nih.gov/24164123/, https://pubmed.ncbi.nlm.nih.gov/24785444/, https://pubmed.ncbi.nlm.nih.gov/29512394/].
👉 An impaired excursion of MN was negatively correlated with nerve conduction velocity, neurophysiological grading scale, and sequential nerve dysfunction [https://pubmed.ncbi.nlm.nih.gov/26764488/, https://pubmed.ncbi.nlm.nih.gov/29512394/].
👉 Park indicated that decreased nerve displacement due to fibrosis of the connective tissue happened in the later stage of CTS, instead of in the earlier stages [https://pubmed.ncbi.nlm.nih.gov/28433831/]. Once median nerve compression and traction occurred, the intraneural microcirculation and the supporting connective tissue were altered and injured at first, followed by demyelination and degeneration of the median nerve [https://pubmed.ncbi.nlm.nih.gov/25630774/]. This process may explain why the reduction in nerve displacement was more relevant to fibrosis of SSCT at the later stage of CTS.
📍 Median nerve biased neural mobilization exercises and tendon gliding exercises might be therapeutically beneficial because of their effect on decreasing intraneural edema, improving median nerve mobility and mechanosensitivity https://pubmed.ncbi.nlm.nih.gov/34969010/, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2565076/, https://onlinelibrary.wiley.com/doi/abs/10.1002/jor.20310, https://pubmed.ncbi.nlm.nih.gov/33618231/, https://pubmed.ncbi.nlm.nih.gov/34784245/.
Illustration: https://pubmed.ncbi.nlm.nih.gov/12050342/
