Supervisors info:
Θωμάς Νικολόπουλος, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ, Επιβλέπων
Παύλος Μαραγκουδακής, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Αλέξανδρος Δελίδης, Επίκουρος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Summary:
The aim of the present thesis is the evaluation of ASSR reliability in the audiological assessment of newborns, children, and adults with normal hearing and all degrees of hearing loss.
Material and methods: We assessed all article in the English literature that compared ASSR thresholds with behavioral audiometry thresholds (mainly pure tone audiogram). Surveys with auditory neuropathy and case reports (numbers < 5) were excluded from further analysis.
Results-Conclusions: From the initial 255 articles, only 23 fulfilled the inclusion criteria and were further analyzed. There was a wide variability and heterogeneity in these articles as some of them did not include audiological details or even thresholds, other used correlation coefficients, other percentages or standard deviations, and some article compared with ASSR audiograms performed even years later. These weaknesses make the related comparisons and conclusions rather weak. However, most of the papers tend to agree in some outcomes and therefore outcomes and related differences can be extracted with adequate credibility. ASSR as an audiological method was found to be very reliable in the hearing assessment of newborns, children, and adults. The correlation of ASSR thresholds in 500, 1000, 2000, and 4000 HZ with the respective thresholds of behavioral audiometry (mainly pure tone audiogram) was found to be very high in all surveys included in the present study. The correlation coefficients varied between 0.75 and 0.97 (higher than 0.90 in most studies.
The mean difference between audiogram and ASSR varied between 2 and 19 dB in the vast majority of studies. There were surveys reporting that in 85% of their subjects the difference between audiogram and ASSR was smaller than 20 or even 10 DB (in some categories of hearing loss 4 DB).There was a steady trend for reporting higher reliability of ASSR in moderate to severe hearing loss and relatively less reliability in normal or practically deaf ears. However, there were also studies suggesting that ASSR reliability remains very high in the latter categories as well. Finally, we also found a steady trend in reporting higher ASSR reliability in 1000, 2000, and 4000 HZ and relatively less reliability in 500 HZ. However, there were also studies suggesting that ASSR are very reliable irrespective of frequency. The above mentioned differences in outcomes may attributed to factors related to ASSR examination methods such as external noise, number of sweeps or even time of examination.
Keywords:
ABR - auditory brainsteam response, ASSR - auditory steady-state-respose, Brainsteam response, Child, Electrophysiological hearing testing, Hearing loss
