Auditory Brainstem Response (ABR) wave V latency is prolonged bilaterally with inter-wave I–V interval increased. Which site of lesion does this most strongly suggest?

• A Cochlear (sensory) pathology
• B Eighth nerve lesion (e.g., acoustic neuroma)
• C Brainstem (retrocochlear/central) pathology ✓
• D Auditory cortex dysfunction

Explanation

The I–V interwave (central conduction time) interval reflects neural transmission from the distal eighth nerve (wave I — cochlear nerve) through the brainstem pathways to the inferior colliculus (wave V). A bilaterally prolonged I–V interval with bilateral involvement points to brainstem (central/retrocochlear) pathology such as demyelination (multiple sclerosis), posterior fossa mass, or brainstem infarct. A unilaterally absent or delayed wave I–V is more suggestive of acoustic neuroma on that side.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.