June 28, 2008 Preliminary research culled from a national medical insurance records database in Taiwan suggests that sudden loss of hearing might be an early sign of vulnerability to stroke, foreshadowing an actual cerebrovascular event by as much as two years, according to a study reported in Stroke: Journal of the American Heart Association.
Five-year follow-up data on 1,423 patients hospitalized for an acute episode of sudden sensorineural hearing loss (SSNHL) showed they were more than one-and-a-half times more likely to suffer a stroke than a control group of 5,692 patients who had been hospitalized for an appendectomy.
Because the insurance records may not have contained reliable information, such as correct diagnostic codes or confounding factors, the findings should be considered tentative, said lead investigator Herng-Ching Lin, Ph.D., a professor at Taipei Medical University School of Health Care Administration.
"To the best of our knowledge, no study has investigated the incidence or risk of cerebrovascular diseases developing following the onset of sudden sensorineural hearing loss," Lin said. "But because this is the first time any association has been suggested, and because there were many limitations in the data, the results need to be interpreted cautiously until additional independent studies are performed."
The findings are limited because there is not a clear universal definition for SSNHL in the database that was reviewed. "Secondly, the database did not contain information regarding severity of hearing loss, extent of hearing recovery, tobacco use, body mass index and the medical history of cardiovascular disease and atrial fibrillation -- all of which can contribute to stroke risk," Lin explained.
Nonetheless, the researchers recommend that all SSNHL patients undergo a comprehensive neurological exam and blood testing to gauge their risk profile for stroke.
Co-authors are Pin-Zhir Chao, M.D. and Hsin-Chien Lee, M.D. Individual author disclosures can be found on the manuscript.
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