Auditory brainstem response testing shows a prolonged interval between waves I and V. This finding is most consistent with which condition?

Auditory brainstem response testing shows a prolonged interval between waves I and V. This finding is most consistent with which condition?

• A. Retrocochlear pathology, such as an acoustic neuroma
• B. Conductive hearing loss due to middle ear effusion
• C. Cochlear hearing loss due to ototoxicity
• D. Middle-ear dysfunction due to otosclerosis

Answer: (A)

The main concept is that the I–V interpeak latency on an auditory brainstem response reflects neural conduction along the brainstem from the auditory nerve to higher brainstem centers. When this interval is prolonged, it signals slowed transmission beyond the cochlea—retrocochlear pathology. An acoustic neuroma or other lesion on the eighth nerve pathway disrupts and slows neural conduction in the brainstem, increasing the I–V interval. In contrast, conductive middle-ear problems delay sound before it reaches the cochlea and primarily affect thresholds rather than brainstem conduction time, so the I–V interval remains typically normal. Cochlear (ototoxic) loss changes the cochlear input and wave I amplitude but usually does not elongate the brainstem I–V timing. Otosclerosis affects the middle ear mechanics without creating retrocochlear delay. So, the pattern is most consistent with a retrocochlear lesion such as acoustic neuroma.

The main concept is that the I–V interpeak latency on an auditory brainstem response reflects neural conduction along the brainstem from the auditory nerve to higher brainstem centers. When this interval is prolonged, it signals slowed transmission beyond the cochlea—retrocochlear pathology. An acoustic neuroma or other lesion on the eighth nerve pathway disrupts and slows neural conduction in the brainstem, increasing the I–V interval. In contrast, conductive middle-ear problems delay sound before it reaches the cochlea and primarily affect thresholds rather than brainstem conduction time, so the I–V interval remains typically normal. Cochlear (ototoxic) loss changes the cochlear input and wave I amplitude but usually does not elongate the brainstem I–V timing. Otosclerosis affects the middle ear mechanics without creating retrocochlear delay. So, the pattern is most consistent with a retrocochlear lesion such as acoustic neuroma.