In a patient with a unilateral acoustic neuroma, which ABR finding is most characteristic?
- A Prolonged absolute latency of Wave I with normal interpeak intervals
- B Bilateral absence of all ABR waveforms
- C Absent or poorly formed Wave V with prolonged I-V interpeak latency on the affected side ✓
- D Normal ABR with increased Wave III amplitude
Correct answer: C. Absent or poorly formed Wave V with prolonged I-V interpeak latency on the affected side
Explanation
Acoustic neuroma (vestibular schwannoma) causes retrocochlear pathology. The hallmark ABR finding is a prolonged I-V interpeak latency on the affected side, often with absence or degradation of Wave V. This reflects delayed neural transmission through the tumour-compressed or invaded nerve fibres. Wave I (generated at the cochlear nerve end) may still be present if the cochlea is unaffected. ABR has ~90–95% sensitivity for large acoustic neuromas; MRI with gadolinium remains the gold-standard investigation.
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.