Pathological findings in subsynovial connective tissue in idiopathic carpal tunnel syndrome.

Recent studies suggest that in patients with carpal tunnel syndrome, pathological changes occur in the subsynovial connective tissue. Such changes are non-inflammatory synovial fibrosis and vascular proliferation. Thickening of the tendon sheet may cause an increase of canal pressure and damages to the median nerve in the wrist; however, the causes of such events still remain to be clarified. We examined synovial specimens from 26 patients operated on for idiopathic carpal tunnel syndrome. Analysis included histological, ultrastructural and immunohistochemical examination in order to establish a pathological underlying pattern. An explanation for the pathogenesis of the found changes suggested. Our data confirm the presence of a non-inflammatory fibrosis with irregular bundles of collagen. De novo blood vessel formation was also noted. Interestingly the neo-angiogenesis consists of anomalous vessels and may be triggered from various cell types secreting vascular endothelial growth factor (VEGF), including macrophage-like elements similar to endothelial progenitor cells. Therefore, we believe that in the future a non-surgical management of carpal tunnel syndrome might be conjecturable via anti-VEGF drugs.