A patient has unilateral progressive sensorineural hearing loss with significant decay of the stapedial reflex and no identifiable waves on auditory brainstem response. The pattern most strongly suggests which type of disorder?

• A. Cochlear disorder
• B. Temporal lobe lesion
• C. Middle-ear dysfunction
• D. VIIIth-nerve disorder

Answer: (D)

The main idea is that this combination points to a retrocochlear (VIII nerve) problem rather than a cochlear or middle-ear issue. An acoustic (stapedial) reflex decay that is significant, along with no identifiable waves on the auditory brainstem response, indicates neural pathway involvement beyond the cochlea. The ABR tests the integrity of the auditory pathway from the eighth nerve through the brainstem; when waves can’t be reliably evoked, it suggests that conduction is disrupted along that neural route, which is characteristic of VIII nerve pathology such as a vestibular schwannoma.

In a cochlear disorder, you’d expect the cochlear input to be affected but the neural pathways (and ABR waves) to be relatively preserved, at least in earlier stages. A middle-ear dysfunction would typically cause conductive loss and abnormal tympanometry rather than a pure unilateral sensorineural loss with absent ABR waves. A temporal lobe lesion could alter auditory processing, but the pattern described—unilateral progressive SNHL with absent ABR and reflex decay—is most classic for VIII nerve involvement.

So, the finding is most strongly indicative of a VIIIth-nerve disorder.