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Hearing threshold difference between ears and risk of acoustic tumor
1Seattle Ear Clinic, WA 98122.
Summary
A significant hearing difference between ears, especially at higher frequencies (1-8 kHz), indicates a higher risk of acoustic neuroma. A difference of 20 dB or more warrants MRI, while 5-20 dB suggests auditory brainstem response testing.
Area of Science:
- Audiology
- Neurotology
- Diagnostic Imaging
Background:
- Acoustic neuroma (vestibular schwannoma) is a benign tumor on the vestibulocochlear nerve.
- Early detection of acoustic neuroma is crucial for effective management and preserving hearing.
- Quantifying interaural hearing asymmetry can aid in identifying patients at risk.
Purpose of the Study:
- To determine the degree of hearing threshold difference between ears that signifies a sufficient risk of acoustic neuroma.
- To establish evidence-based criteria for diagnostic referrals (MRI and auditory brainstem response testing).
Main Methods:
- Audiometric hearing thresholds were measured in 210 patients with confirmed unilateral acoustic tumors and 112 controls.
- Interaural threshold differences were calculated at octave frequencies from 250 Hz to 8 kHz.
- The effectiveness of different frequency differences for diagnostic risk stratification was ranked.
Main Results:
- The most effective frequencies for identifying threshold differences were 2 kHz, 4 kHz, and 1 kHz.
- An average interaural threshold difference of ≥20 dB at 1-8 kHz was identified as a criterion for MRI referral.
- An average interaural threshold difference of 5-20 dB at 1-8 kHz was identified as a criterion for auditory brainstem response (ABR) testing referral.
Conclusions:
- Specific interaural hearing threshold differences can effectively stratify patients for acoustic neuroma diagnostic testing.
- Utilizing these audiometric criteria can improve the efficiency of diagnostic workups for suspected acoustic neuromas.