ABA Advanced Diagnostics & Troubleshooting 3 — Questions and Answers
Question 1: A child's ABR shows a present Wave V at 30 dB nHL but absent Waves I–IV. What is this pattern most consistent with?
- Conductive hearing loss
- Auditory neuropathy spectrum disorder (Correct answer)
- Normal hearing
- Cochlear dead region
Correct answer: Auditory neuropathy spectrum disorder
In ANSD, Wave V may be present but earlier waves (especially Wave I) are absent due to disordered neural synchrony despite intact cochlear function.
Question 2: A high-frequency audiogram notch at 6000 Hz that is not present at 4000 Hz is most likely caused by:
- Noise-induced hearing loss
- Age-related hearing loss
- Ototoxic drug exposure (Correct answer)
- Acoustic neuroma
Correct answer: Ototoxic drug exposure
Ototoxic damage (e.g., from cisplatin or aminoglycosides) typically begins in the basal cochlea, creating a high-frequency notch that may first appear at 6000–8000 Hz.
Question 3: During wideband acoustic immittance (WAI) testing, a patient shows a tympanometric resonant frequency of 1500 Hz. This finding suggests:
- Stiffness-dominated middle ear (e.g., otosclerosis) (Correct answer)
- Mass-dominated middle ear (e.g., ossicular chain discontinuity)
- Normal middle ear function
- Eustachian tube dysfunction
Correct answer: Stiffness-dominated middle ear (e.g., otosclerosis)
A higher resonant frequency indicates a stiffness-dominated system; normally the middle ear resonates near 800–1200 Hz, so elevation points to conditions like otosclerosis.
Question 4: In a patient with unilateral sensorineural hearing loss, ipsilateral MEMR is present but contralateral MEMR is absent. The probe is in the normal ear. What does this pattern indicate?
- Left afferent lesion (CN VIII)
- Right efferent lesion (CN VII)
- Brainstem lesion disrupting crossed pathways (Correct answer)
- Middle ear pathology in the probe ear
Correct answer: Brainstem lesion disrupting crossed pathways
When the ipsilateral reflex (probe and activator same ear) is present but the contralateral reflex (activator in the other ear, probe in normal ear) is absent, a lesion disrupting crossed brainstem pathways is implicated.
Question 5: A patient's DPOAE input/output function shows lower DP levels than expected at all f2 frequencies. This is most consistent with:
- Outer hair cell dysfunction (Correct answer)
- Inner hair cell dysfunction
- Neural hearing loss
- Middle ear effusion
Correct answer: Outer hair cell dysfunction
DPOAEs are generated by outer hair cells; globally reduced DP output across frequencies indicates outer hair cell dysfunction.
Question 6: Which ABR finding is most characteristic of a space-occupying lesion on the auditory nerve (e.g., vestibular schwannoma)?
- Absent Wave V only
- Prolonged I-V interpeak interval or absent waveform on the affected side (Correct answer)
- Bilateral prolonged Wave I latency
- Shortened Wave III-V interval
Correct answer: Prolonged I-V interpeak interval or absent waveform on the affected side
Retrocochlear lesions such as vestibular schwannomas classically cause a prolonged I-V interpeak interval or complete waveform absence on the ipsilateral side.
Question 7: In auditory steady-state response (ASSR) testing, responses are recorded at stimulus modulation rates of 80–100 Hz to minimize interference from:
- Cochlear microphonics
- Myogenic artifacts
- Alpha brain waves (Correct answer)
- Slow cortical potentials
Correct answer: Alpha brain waves
Alpha brain wave activity (8–13 Hz) and other cortical noise are reduced at 80–100 Hz modulation rates, improving signal-to-noise ratio for threshold estimation.
ABA Advanced Diagnostics & Troubleshooting 3
A child's ABR shows a present Wave V at 30 dB nHL but absent Waves I–IV.
What is this pattern most consistent with?