Pseudo air-bone gap in sensorineural hearing loss: Effect of signal frequency and degree of hearing loss - implications for clinical diagnosis

Introduction: Pseudo air-bone gaps (ABGs) in the audiogram can lead to a false diagnosis of middle ear pathology where none exists. While it is known that the magnitude of such false ABGs are frequency dependent, the effect on the severity of hearing loss on this relationship needs more clarity. Objective: The purpose of the study was to identify frequencies that are susceptible to pseudo-ABGs and investigate the effect of the degree of hearing loss on the magnitude of such air-bone gaps. Materials and Methods: A retrospective analysis of the ABG in three degrees of sensorineural hearing loss: mild (26-40 dB HL), moderate (41-55 dB HL), and moderately severe (56-70 dB HL) was carried out. One hundred and fifty samples were considered in each category (18-60 years). Differences across frequencies and degree of hearing loss were assessed. Results: Large ABGs were observed at 250 Hz and 4000 Hz, and the ABGs significantly increased with the degree of hearing loss at 250 Hz and 500 Hz. Conclusions: Caution needs to be exercised while interpreting the ABG at the low frequencies and 4000 Hz, especially when the degree of hearing loss is moderate and higher, to avoid the misdiagnosis of a conductive component in a sensorineural pathology.