Hidden or subclinical cochleopathy in idiopathic subjective tinnitus: extended high frequency audiometry and otoacoustic emission

Abstract

Abstract Introduction Tinnitus patients with apparently normal hearing represent a challenge to models of tinnitus generation which rely on compromised cochlear function. Although it is known that any cochlear changes even subclinical can cause tinnitus, our rational was to apply an objective measure that can aids in the quantification of these cochlear changes. Objective The of study was designed to evaluate possible hidden or subclinical cochlear dysfunction in idiopathic subjective tinnitus patients with normal hearing using extended high frequency audiometry and otoacoustic emissions. Methods Forty seven subjects enrolled in this study divided into control group (20 normal hearing adults without tinnitus) and a study group (27 normal hearing adult patients complaining of tinnitus). Extended high frequency (EHF) audiometry and otoacoustic emissions (OAEs) in addition to tinnitus matching study were done for all subjects. Study group further subdivided according to tinnitus pitch matching into low- and high-pitched tinnitus groups. Results The data of this study showed that patients with normal hearing sensitivity in the conventional frequency range (up to 8\u2009kHz) and reporting tinnitus, present alterations of the auditory system in the affected side. This affection manifested as elevated EHF audiometry thresholds at 9000, 10,000, 11,200, 14,000 and 16,000\u2009Hz. Most tinnitus patients had pitch matching frequency at high frequency range between (3000 and 8000\u2009Hz). Transient evoked OAEs and distortion product OAEs amplitude was lower in tinnitus patients relative to controls. Conclusion The ultrahigh frequency hearing loss is not hidden – but – exists and awaits identification with appropriate testing.