On auditory brainstem response (ABR) testing, which waveform peak corresponds to the cochlear nerve (CN VIII) action potential and arises from the distal CN VIII near the cochlea?
- A Wave I ✓
- B Wave II
- C Wave III
- D Wave V
Explanation
ABR Wave I represents the compound action potential of the distal cochlear nerve (CN VIII) recorded near the cochlea. Wave II arises from the proximal CN VIII at the internal auditory canal/cochlear nucleus. Wave III originates from the cochlear nucleus. Wave IV is from the superior olivary complex (SOC), and Wave V — the most robust, used for threshold estimation — arises from the lateral lemniscus/inferior colliculus junction. In acoustic neuroma, the interwave latency I–III is prolonged (affecting the CN VIII segment). Wave V is the most clinically important for threshold determination in infants.
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.