Perineurial cell basement membrane thickening and myelinated nerve fibre loss in diabetic and nondiabetic peripheral nerve.

Diabetic neuropathy is associated with changes in the extracellular matrix of the perineurium, including thickening of the basement membrane of the perineurial cells. Peripheral vascular disease (PVD) is a common vascular condition that can occur in the absence or presence of diabetes. Thickening of the vascular basement membrane of the vasa nervorum is associated with both diabetes and nondiabetic peripheral vascular disease. However, perineurial cell basement membrane (PCBM) thickening in the nondiabetic PVD state has not, until now, been investigated. In this study, 36 nerve fascicles were examined from three patient groups: a diabetic group, a nondiabetic PVD group, and a group free of both PVD and diabetes (control group). PCBM thickness, fascicle size, and myelinated nerve fibre (MNF) density were measured in all three groups. Endoneurial blood vessels were also observed for evidence of morphological changes. The results showed that the thickness of the PCBM is significantly greater in the diabetic group in comparison with both the control and the nondiabetic PVD group, and this increase in thickness is linearly related to fascicle size. The thickness of the PCBM was not significantly different between the nondiabetic PVD and control groups. Although both the nondiabetic PVD and diabetic groups showed a loss of myelinated nerve fibres in comparison with the control group, this loss was statistically greater in the diabetic group. The endoneurial blood vessels of both the diabetic and nondiabetic PVD groups showed evidence of endothelial cell hyperplasia, hypertrophy, and basement membrane reduplication.