Effect of synovial transthyretin amyloid deposition on preoperative symptoms and postoperative recovery of median nerve function among patients with idiopathic carpal tunnel syndrome

Background The clinical characteristics of wild-type transthyretin amyloid deposition among patients with carpal tunnel syndrome (CTS) have not been well investigated. Methods One-hundred and seven patients with idiopathic CTS who underwent carpal tunnel release were enrolled. They underwent physical examination of the hand, nerve-conduction study, and magnetic resonance imaging (MRI) study of the wrist, and completed a patient-oriented questionnaire. The tests, except for MRI, were repeated 1, 3, and 6 months postoperatively. Synovial tissue was obtained during surgery and analyzed by Congo red and immunohistochemical staining. Ordinal logistic regression analysis was used to evaluate the significance of different clinical and subjective findings between patients with and without amyloid deposition. Postoperative improvements were also compared. Results Wild-type transthyretin amyloid deposition was observed for 38 patients. Greater symptom severity and 2-point discrimination scores, and larger cross-sectional areas of the carpal tunnel, were significantly correlated with a larger amount of preoperative amyloid deposition. However, the presence and amount of preoperative amyloid deposition did not affect postoperative improvements in physical findings and nerve-conduction studies. Conclusions Although transthyretin amyloid deposition can worsen CTS symptoms, postoperative improvements were similar for patients with and without this deposition.