Metabolic alterations and hearing acuity: lack of a significant clinical correlation

Objective: To contribute to assessing the extent of the clinical significance of metabolic alterations in terms of hearing deterioration. Study design: The design enabled comparison of the serum level of cholesterol, apolipoproteins, glucose and uric acid in a homogeneous, controlled population of subjects with normal hearing and with symmetrical sensorineural hearing loss, respectively. All subjects were enrolled within the Brisighella Heart Study (BHS), a prospective, population based longitudinal epidemiological investigation involving almost 3000 randomly selected Caucasian subjects living in Brisighella, a small town in northern Italy. Results: No statistical difference was identified in the metabolic assessment of the two groups (normal hearing vs. impaired hearing). In particular, alteration of the serum lipids, glucose and uric acid parameters is not significantly associated with hearing loss (p > 0.01). Conclusions: The findings, apparently in disagreement with common opinion, seem to imply that the role of metabolic disorders is not pre-eminent in the genesis of non-acute hearing loss. It is possible to hypothesize that all mechanisms regulating the microcirculation of the inner ear can constitute a ‘buffer’ against the related cellular damage. It is likely that if a convenient and sufficiently stable degree of oxygenation is maintained, this might be enough to preserve hearing function even under unfavourable metabolic conditions.