The Threshold That Won't Sit Still
A 34-year-old man is referred for a second opinion after two prior audiograms at an outside clinic reported a mild-to-moderate rising sensorineural loss in the right ear (PTA 38 dB HL) and normal hearing in the left ear. He denies noise exposure, ototoxic medication, head trauma, and family history. Otoscopy is clear bilaterally. At your clinic, pure-tone thresholds by pulsed-tone and continuous-tone presentation differ by 15 dB at 500 and 1000 Hz in the right ear only, with better thresholds on continuous tones. Speech recognition in quiet is 96% right and 98% left at 60 dB HL. Acoustic reflexes are present bilaterally at 85-90 dB HL with normal tympanometry. Word recognition in the right ear drops from 96% to 72% when the left ear is masked.
1. What is the most likely explanation for the inconsistent right-ear thresholds, and what pattern of masking results would confirm your interpretation?
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The picture is a functional (non-organic) hearing loss in the right ear. Key clues:
- Pure-tone thresholds improve with continuous vs. pulsed tones by 15 dB at two octaves - real cochlear loss does not behave this way, and pulsed tones are the standard for detecting this discrepancy.
- Normal acoustic reflexes at 85-90 dB HL are inconsistent with a genuine 38 dB HL PTA; reflexes should be present at levels consistent with the true threshold.
- Speech recognition in quiet is excellent (96%), far better than expected for a moderate loss.
- The right-ear word recognition drop from 96% to 72% when masking the left ear is the diagnostic giveaway: masking the good ear removes the crossover advantage, exposing the true (better) hearing.
Confirmatory pattern: on pure-tone masking, the right ear's masked thresholds should improve toward normal (shift toward the left-ear/true level), and a Stenger test should be positive - the patient will fail to respond to a tone presented to the "better" (right) ear when a simultaneous tone is presented to the left ear at a level he should hear. A positive Stenger (no response when both ears are stimulated) supports non-organic loss. Re-test after reassurance and consider a repeat audiogram with masking throughout; document clearly and refer for counseling rather than labeling as sensorineural loss.
2. How should you counsel this patient and document the findings, and what would change if he were a workers' compensation claimant?
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Counseling: Explain in plain language that the test results are inconsistent with organic hearing loss and that his hearing appears better than the first test suggested. Avoid accusatory language; frame it as "the test results don't match, so we need to re-check." Offer repeat testing with masking and reassurance, and screen for anxiety or secondary gain without confrontation.
Documentation: Record both pulsed- and continuous-tone thresholds, the masking conditions, the Stenger result, acoustic reflex levels, and the speech-in-noise/masked word recognition scores. State the interpretation ("findings consistent with non-organic hearing loss") and the recommendation for re-evaluation. Do not record a sensorineural loss diagnosis that the data do not support.
If a workers' comp claimant: The stakes change - the audiogram may drive a permanent impairment rating. In that case, do not rely on a single session. Use a full battery (pure-tone with masking, Stenger, acoustic reflexes, otoacoustic emissions, and if needed auditory brainstem response) to establish the true threshold objectively. Document the objective measures, because a non-organic finding can have medicolegal consequences and you must be able to defend the interpretation. Coordinate with the referring physician and, if appropriate, a second examiner.
3. What is the danger of simply accepting the outside clinic's 38 dB HL PTA and fitting a hearing aid?
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Fitting amplification to a non-organic threshold risks over-amplification of a normal-hearing ear, which can cause discomfort, feedback, and even noise-induced damage over time. It also validates an inaccurate diagnosis, potentially entrenching the functional loss and creating a dependent patient. The patient's excellent speech recognition and normal reflexes indicate he does not need gain at the reported levels. The correct path is to resolve the discrepancy first, then fit only if a genuine loss is confirmed by objective measures. This is a judgment call the exam favors: the audiogram is data, not truth.