Did you know a simple audiogram may help predict your heart disease risk?
In a study titled Audiometric testing as a predictor for Cardiovascular disease published in
Laryngoscope 119 Mar 2009 researchers hypothesized that low-frequency hearing loss is associated with underlying cardiovascular disease. Their conclusion? Audiogram patterns correlate strongly with cerebrovascular and peripheral arterial disease and may represent a screening test for those at risk. Patients with low-frequency hearing loss should be regarded as at risk for cardiovascular events, and appropriate referrals should be considered.
What commonly causes hearing loss?
We know that environmental noise and exposures, systemic disease, and family inheritance can lead to hearing loss. Years ago Dr. Schuknecht correlated audiometric patterns to hearing loss. He described classic character of presbycusis (age related hearing loss) seen on audiometric tests to cochlear pathology. The Schuknecht classification, as a general template for age-related hearing loss, has been validated through investigation. The presbycusis patterns include strial, cochlear conductive, sensory, and neural hearing losses.
Presbycusis is typically the result of degeneration within the cochlea, most commonly to outer hair cells but also to inner hair cells, spiral ganglion neurons, or the stria vascularis.
What is the Stria Vascularis?
The stria vascularis, in the lateral wall of the cochlea, is critical for establishing the endocochlear potential necessary for the propagation of auditory signals to the central nervous system. The stria vascularis is a capillary-rich structure fed by radial branches of the spiral modiolar artery. Arteries feeding the stria vascularis are terminal vessels with no anastomoses to supplement
flow or accommodate for spasm or occlusion. Additionally, the strial capillary network is relatively sparse at the apex when compared with the dense organization at the base. These anatomical features leave the apical cochlea exquisitely sensitive to ischemia. A reduction in endocochlear potential and clinically significant hearing loss occurs almost immediately after vascular occlusion
or anoxia. The vascular anatomy of the stria at the cochlear apex (low frequencies) establishes this area as a sensitive marker for systemic cardiovascular disease.
What next?
So that lowly audiogram may be a real help to you after all. You should seek out a trained audiologist (CCC-A designation) to evaluate you, especially if you have low frequency hearing loss and risk factors such as hypertension, diabetes mellitus, hyperlipidemia/cholesterolemia, age >75 years, and a history of smoking or prior events like myocardial infarction, diagnosis of coronary artery disease, stroke, transient ischemic attack, and claudication.
