Objectives: The goals of this study are to characterize the distribution of melanin pigmentation in the human cochlea and to investigate differences in pigment content between races.
Methods: Human temporal bone specimens from the Johns Hopkins Temporal Bone Collection were examined. Demographic, clinical, and audiometric data were analyzed. Melanin pigmentation in the cochlea was quantified in each specimen.
Results: Nineteen African-American (AA) and 27 Caucasian specimens were selected for the study. The mean ages were 64 and 70 years for AA and Caucasian specimens, respectively (p = 0.21). At all cochlear turns, AA specimens contained significantly more pigmentation in the stria vascularis (p = 0.0003) and Rosenthal's canal (p < 0.0001) compared with Caucasian specimens. Strial melanin content increased significantly with age. Cochlear pigmentation content was not associated with sex or hearing thresholds.
Conclusion: Melanin pigmentation is significantly more abundant in AA cochleae than in Caucasian cochleae. This study provides a detailed description of pigmentation in the cochlea and may help to explain the observed racial differences in hearing thresholds.