Cochlear microphonics in children
Reviewed by Srikanth Chundu

Cochlear microphonics (CM) are generated mainly from outer hair cells and are routinely tested in children with hearing loss in some parts of the world. In this retrospective study, the aim was to compare the cochlear microphonics features (mainly CM amplitude across different intensities) among children with auditory neuropathy spectrum disorder (ANSD), children with autism spectral disorders (ASD), children with cochlear sensorineural hearing loss (SNHL) and a normal hearing control group. The ANSD and SNHL children were further divided based on the presence or absence of distortion product otoacoustic emissions (DPOAEs). The age of the children ranged from six months to eight years. The results of the study indicated that with an increase in the intensity of the signal, the CM’s amplitude reduced. There was no difference in CM amplitude between control, ASD and ANSD with DPOAEs groups. Age does not correlate with the CM amplitude except for the control group, where there was a negative correlation (level 70 dBnHL). Another finding which is of interest, especially to clinicians dealing with paediatrics, is that in children with ANSD, even in the absence of DPOAEs, CM were still present. The amplitude of the CM varied depending on the presence of DPOAEs. Those groups with DPOAES, including SNHL and ANSD, showed significantly greater CM amplitude compared to children with no DPOAES. The study highlights the importance of including CM as a part of test battery, especially when diagnosing children using ABR and OAEs, to avoid any false negative results for ANSD. This is important considering the presence of CM even in the absence of DPOAEs. Please refer to the study to find more about the acquisition parameters used.

Cochlear microphonics recording during ABR threshold testing in children.
Osman Dabbous, A.
HEARING, BALANCE AND COMMUNICATION
2016;14(4):163-82.