Histopathologic Evaluation of Vascular Findings in the Cochlea in Patients With Presbycusis.

Abstract

Age-related changes in cochlear vessel wall thickness in human temporal bones have not been described previously. To compare thickness of the spiral modiolar artery and strial capillaries and to investigate strial atrophy and vessel loss in temporal bones with and without presbycusis. This retrospective case-control study examined the autopsy reports of 1024 patients in the temporal bone collection at the University of Minnesota. Inclusion criteria consisted of being 60 years or older with sensorineural hearing loss and progression of hearing loss with age (presbycusis group). Age-matched controls had no record of hearing loss. All patients underwent pure-tone audiometry. Exclusion criteria included a history of otologic disease, ototoxic drug use, head or acoustic trauma, or systemic disease. Data were collected from October 1, 2013, to October 1, 2014. Vessel wall thickness in the modiolar artery and strial vessels, the strial area, and number of strial vessels were measured under light microscopy. Among the 1024 autopsy reports examined, 11 patients (19 temporal bones) with presbycusis (7 men and 4 women; age range, 67-88 years; mean [SD] age, 78 [7] years]) and 15 controls (24 temporal bones) (7 men and 8 women; age range, 67-94 years; mean [SD] age, 79 [8] years) met the inclusion criteria. Compared with the control group, the presbycusis group had significantly increased mean (SD) thickness of vessel walls in the modiolar arteries (6.73 [2.39] vs 5.55 [0.86] μm; P = .02) and the strial capillaries in the lower basal (1.57 [0.21] vs 1.39 [0.15] μm; P = .005), upper basal (1.62 [0.28] vs 1.40 [0.13] μm; P < .001), lower middle (1.68 [0.22] vs 1.39 [0.20] μm; P < .001), upper middle (1.74 [0.39] vs 1.40 [0.19] μm; P = .01), and apical (1.70 [0.36] vs 1.47 [0.21] μm; P = .04) turns of the cochlea. Compared with the control group, the presbycusis group had significant loss of strial area in the lower basal (6614 [1559] vs 8790 [1893] μm2; P = .002), upper basal (6387 [2211] vs 9105 [2700] μm2; P < .001), lower middle (5140 [1471] vs 7269 [2181] μm2; P = .003), upper middle, (5583 [1742] vs 7206 [2258] μm2; P = .02), and apical (4286 [1604] vs 6535 [2454] μm2; P < .001) turns of the cochlea; in the vessel area in the lower basal turn (74.65 [127.74] vs 124.92 [89.04] μm2; P = .01); and in the number of vessels in the lower basal (1.00 [0.78] vs 1.94 [0.93]; P = .008) and lower middle (1.00 [0.78] vs 1.94 [0.93]; P = .04) turns of the cochlea. The histopathologic findings of increased thickness of the vascular walls of the modiolar arteries and stria vascularis, increased strial atrophy, and decreased number of strial vessels may have led to decreased cochlear microcirculation. Deficiency in the circulation and perfusion of the cochlea may be a factor in presbycusis.