Proliferation of epineurial capillaries and smooth muscle cells in angiopathic peripheral neuropathy.

Proliferation of epineurial capillaries and smooth muscle cells in human sural nerves has been documented. These are basically independent changes, although both can occur in the same nerve. Proliferated epineurial capillaries were seen in association with arterial stenosis or occlusion with or without granulating or granulomatous inflammatory reactions. Although non-specific they appear to be of considerable diagnostic value indicating compensatory hypervascularization subsequent to peripheral focal ischemia. Separation and numerical increase of epineurial smooth muscle cells, on the other hand, was also recognised as a significant though non-specific alteration occurring in various inflammatory, immunogenetic, or other, non-inflammatory angiopathies. The youngest (1.3 years) and the oldest individual (104 years) studied, as well as many other documented and non-documented cases, did not show this type of change. Smooth muscle cells may survive isolated or focally separated from adjacent vessel walls in the epineurium.