Clinical interpretation of brainstem evoked response audiometry abnormalities in cochlear pathology

Area of Science:

• Audiology
• Neuroscience
• Otolaryngology

Background:

• Sensorineural hearing loss (SNHL) diagnosis relies on audiological tests.
• Brainstem Evoked Response Audiometry (BERA) assesses auditory pathway function.
• Distinguishing cochlear from retrocochlear pathology is crucial for SNHL management.

Purpose of the Study:

• To investigate the effects of cochlear lesions on BERA parameters in SNHL patients.
• To evaluate the utility of electrocochleography (ECochG) in conjunction with BERA for diagnosing cochlear pathology.

Main Methods:

• Pure tone audiometry and standard BERA were performed on 45 SNHL patients.
• ECochG was utilized in cases where wave I was absent in BERA.
• Patients included those with Meniere's disease, acoustic trauma, and ototoxic drug-induced SNHL.

Main Results:

• Cochlear lesions caused latency prolongation for BERA waves I, III, and V, especially at lower stimulation levels.
• This latency effect was compensated at higher stimulation levels due to steeper latency-intensity curves in recruiting cochleas.
• Cochlear lesions did not prolong central conduction time (CCT) and could degrade waveform replicability.
• ECochG successfully visualized wave I in cases of poor BERA waveform resolution.

Conclusions:

• Cochlear lesions impact BERA latencies, but this effect can be masked at high stimulus levels.
• Central auditory conduction time (CCT) remains unaffected by cochlear pathology.
• ECochG is a valuable tool for confirming cochlear lesions when BERA wave I is not discernible, improving diagnostic accuracy.