Audiometric findings in a patient with an early-onset progressive monosymptomatic low frequency hearing loss

Background: Objective audiometric methods such as the measurement of otoaco ustic emissions and auditory evoked potentials (click evoked and notched-no ise auditory evoked brainstem potentials, auditory evoked cortical potentia ls) can provide helpful information. However, information derived from the individual test is limited and each method contains specific restrictions. To illustrate the possible audiometric pitfalls this work presents a case h istory. Case report: The puretone audiometry showed a severe hearing loss at low fr equencies up to 2 kHz, a slight hearing loss for higher frequencies up to 6 kHz and almost normal hearing thresholds above 6 kHz. Transitory evoked ot oacoustic emissions could not be detected. While the auditory evoked brains tem responses (ABR) using click-stimuli showed a normal pattern no reproduc ible responses could be derived using the notched-noise technique. Auditory evoked cortical potentials exhibited a normal N1/P2-complex and were detec table down to stimulus levels 0-20 dB above the individual hearing threshol d. Discussion: Click-evoked auditory evoked brainstem potentials are widely re garded as the "gold-standard" of objective audiometry. The example presente d in this work shows that in special cases it may provide false negative re sults. In these special cases auditory tone-evoked cortical potentials may provide better objective information. When objectively assessing the determ ination of the hearing threshold it may be necessary not only to use all el ectrophysiological measurements but also to know their methodical restricti ons and pitfalls.