Acoustic reflex decay testing at 500 Hz shows the reflex amplitude falling to less than half its initial value within 10 seconds of continuous stimulation. This finding is most characteristic of:

• A Cochlear hearing loss with recruitment
• B Otosclerosis with stapes fixation
• C Retrocochlear lesion involving the eighth nerve ✓
• D Normal middle ear mechanics

Explanation

Abnormal reflex decay, defined as more than 50% reduction in reflex amplitude within 10 seconds of sustained stimulation, reflects failure of neural sustenance and is a classic sign of retrocochlear pathology such as vestibular schwannoma. Cochlear lesions typically show brisk, easily elicited reflexes at reduced sensation levels due to recruitment, which distinguishes them from neural lesions on this test.

Reference: Cummings Otolaryngology: Head and Neck Surgery, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.