Ultrastructural changes in peripheral nerves of the fingers of three vibration-exposed persons with Raynaud's phenomenon.

A finger biopsy was performed on three patients with vibration-induced white finger (VWF), and the specimens were examined by electron microscopy for peripheral nerve changes. A characteristic neuropathy with perineurial fibrosis was revealed which was often accompanied by a thickened perineurium with a lamellar structure resembling onion skin. This peculiar fibrosis consisted of elongated cytoplasmic projections of perineurial cells or fibroblasts and a greatly increased amount of collagen which occasionally contained fibrous long-spacing collagen. In the endoneurium, a decrease in the number of nerve fibers and a marked increase in collagen with fibroblasts were noted. Myelinated axons became smaller, and this occurrence suggested incomplete regeneration. The pathological changes were presumably the result of the long-term clinical course of VWF.