[Diabetic changes in the stria vascularis in humans--a study of PAS-stained temporal bone sections]

Sensorineural hearing loss can be caused by diabetes mellitus, and diabetic microangiopathy contributes to diabetic complications such as nephropathy. I compared the outer diameter of strial capillaries, the strial atrophy rate, and basement membrane thickening in the strial capillaries of temporal bone sections from 16 diabetics and 16 non-diabetics matched for age and sex and assessed the correlations between these values and age, duration of disease, fasting blood sugar, and glycohemoglobin. In the non-diabetic group, the minimum and maximum outer diameters of the capillary in the cochlear apical turn were larger than in the basal and middle turns. The strial atrophy rate in the apical turn was higher than in the basal and middle turns. There was no significant difference in basement membrane width between the turns. In the diabetic group, there were no significant differences in minimum outer diameter and basement membrane width between the turns. The maximum outer diameter of the middle turn was larger than that of basal turn. The strial atrophy rate in the apical turn was higher than in the basal and middle turn. In the comparison between the diabetic group and the non-diabetic group, the maximum outer diameter of the apical turn in the diabetics was smaller than in the non-diabetics, the basement membrane width in the basal, apical and all three turns as a whole in the diabetics was thicker than in the non-diabetics, the strial atrophy rate in the basal turn and all three turns as a whole in diabetics was higher than in non-diabetics. There were two correlations in the non-diabetics, between age and strial atrophy rate and between age and basement membrane width in the basal turn, and there were positive correlations in the diabetics, between the strial atrophy rate and fasting blood sugar and between strial atrophy rate and glycohemoglobin in the basal turn. Because of basement membrane thickening toward capillary lumen, these results led to the hypothesis that strial atrophy is one factor in diabetic hearing loss.