A 45-year-old woman presents with progressive unilateral sensorineural hearing loss and tinnitus. Audiometry shows a mild-to-moderate SNHL. Tympanometry is normal. Acoustic reflex testing is performed, and the pattern marked **A** in the diagram is observed: reflex amplitude decay of >50% within 10 seconds at 500 Hz. What is the most appropriate next step in management?
A. MRI of the internal auditory canal with gadolinium to evaluate for retrocochlear pathology
B. Reassure the patient that this represents normal cochlear aging and follow-up in 6 months
C. Prescribe hearing aids and refer for speech therapy
D. Repeat acoustic reflex testing at 2000 Hz and 4000 Hz to confirm the finding
Explanation
Why MRI of the internal auditory canal with gadolinium is correct
The pattern marked A — reflex decay >50% in 10 seconds at 500 Hz — is a hallmark of retrocochlear pathology, particularly vestibular schwannoma or other cerebellopontine angle lesions. The acoustic reflex arc (cochlea → 8th nerve → cochlear nucleus → superior olive → facial motor nucleus → stapedius) becomes fatigued when the 8th nerve is compromised, causing rapid amplitude decay. This finding has 70–80% sensitivity for vestibular schwannoma in the pre-MRI era and remains a powerful objective screening tool. The next step is MRI IAC with gadolinium to confirm the diagnosis and characterize the lesion (Katz Clinical Audiology 7e; AAO-HNS guidelines).
Why each distractor is wrong
Repeat acoustic reflex testing at 2000 Hz and 4000 Hz: Reflex decay can occur normally at higher frequencies (2–4 kHz), making these frequencies unreliable for detecting retrocochlear pathology. The diagnostic value lies in testing at 500 or 1000 Hz only.
Reassure the patient that this represents normal cochlear aging and follow-up in 6 months: Reflex decay >50% in 10 seconds is NOT a normal finding and is NOT consistent with cochlear pathology alone. Cochlear lesions cause elevated reflex thresholds, not abnormal decay. Delaying imaging risks missing a treatable mass.
Prescribe hearing aids and refer for speech therapy: While hearing rehabilitation may eventually be needed, this bypasses the critical diagnostic step. A positive reflex decay test mandates neuroimaging to rule out a structural lesion before symptomatic management alone.
High-YieldNEET PG
Reflex decay >50% in 5–10 seconds at 500/1000 Hz = retrocochlear pathology until proven otherwise; always order MRI IAC with gadolinium; do NOT use 2–4 kHz for this test.
Katz Clinical Audiology 7e; AAO-HNS
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