What is the diagnosis and treatment plan for a 3-year-old child with abnormal cortical auditory evoked potentials (CAEPs) and brainstem auditory evoked potentials (BAEPs) who is not responding to high-frequency sounds in a hearing test?

Diagnosis: Auditory Neuropathy Spectrum Disorder (ANSD) Until Proven Otherwise

This 3-year-old child with present brainstem and cortical evoked potentials but absent behavioral responses to high-frequency sounds most likely has auditory neuropathy spectrum disorder (ANSD), middle ear pathology masking true hearing ability, or a cortical auditory processing disorder—and you must systematically rule out middle ear disease first before pursuing neural diagnoses. 1

The Critical Diagnostic Puzzle

This presentation creates a paradox: the auditory pathway shows electrical activity (evoked potentials are present), yet the child cannot behaviorally detect high-frequency sounds. This mismatch demands immediate investigation because:

• ABR and cortical evoked potentials only test structural integrity of the auditory pathway—they are NOT true tests of hearing because they don't assess whether the child actually perceives and processes sound functionally 2, 3
• The presence of evoked potentials with absent behavioral responses creates a diagnostic puzzle requiring systematic evaluation, with middle ear pathology ruled out first 1

Immediate Diagnostic Algorithm

Step 1: Rule Out Middle Ear Pathology (Most Common and Treatable)

Middle ear dysfunction is the most common and treatable cause of high-frequency hearing loss and must be excluded first 1:

• Perform tympanometry with 1000-Hz probe tone (not 226 Hz, which is unreliable in young children) 1, 3
  • Type A = normal middle ear function
  • Type B = middle ear effusion (most common culprit)
  • Type C = Eustachian tube dysfunction 1
• Otoscopic examination for effusion, cerumen impaction, or structural abnormalities 1

Common pitfall: Middle ear effusion can cause high-frequency hearing loss while evoked potentials remain present because the neural pathway is intact but sound transmission is impaired 1

Step 2: Test for Auditory Neuropathy Spectrum Disorder

If middle ear function is normal, ANSD becomes the primary concern 1:

• Perform click-evoked ABR with BOTH condensation and rarefaction stimuli to detect cochlear microphonics (a hallmark of ANSD) 1, 3
• Obtain otoacoustic emissions (OAEs): OAEs are typically PRESENT in ANSD despite hearing loss, whereas absent OAEs indicate cochlear dysfunction 1
• Frequency-specific ABR using air-conducted tone bursts to map hearing thresholds across all frequencies and identify which specific frequency regions are affected 1, 3

Step 3: Assess Cortical Processing

Since cortical evoked potentials are present, this suggests some degree of cortical processing is occurring 4, 5:

• Cortical auditory evoked potentials (CAEPs) to speech stimuli can provide indication of audibility even when behavioral responses are unreliable 4, 5
• Detection of CAEPs provides confidence (commensurate with detection probability) that the child is detecting sound at the presented level 4
• However, absence of cortical response indicates possibility (not certainty) that sensation level is ≤10 dB 4

Risk Factor Assessment

Obtain detailed history for high-risk factors that increase likelihood of neural hearing loss 1:

• Ototoxic drug exposure: aminoglycosides, vancomycin, furosemide, cisplatin 1
• NICU stay >5 days 1, 3
• History of hyperbilirubinemia, meningitis, or birth asphyxia

Critical Management Decisions

If Middle Ear Pathology is Confirmed:

• Pursue aggressive medical therapy (antibiotics, nasal steroids, observation) before considering surgical intervention 1
• Retest behavioral hearing after middle ear disease resolves

If ANSD is Confirmed:

• Amplification should begin within 1 month of diagnosis if behavioral hearing loss is confirmed—intervention should NOT be delayed waiting for a "definitive" diagnosis 1
• CAEPs to speech stimuli can guide hearing aid fitting in young children who cannot provide reliable behavioral feedback 4, 5
• Early intervention services must be initiated immediately 3

If Behavioral Testing Remains Unreliable:

For children aged 2.5-4 years, play audiometry should be attempted with conditioning to respond through play activities (dropping blocks when sound is heard) 2:

• This age group requires specialized testing approaches as attention span may limit information obtained 2
• Developmental abnormalities or behavioral problems may preclude accurate routine audiometric screening, requiring referral to pediatric audiologist with specialized equipment 2

Important Caveats

• Children under 3 years have normal thresholds up to 15 dB greater than older children due to developmental effects—interpret results accordingly 1
• Absent ABR at 100 dB does NOT necessarily indicate absence of measurable hearing: 43% of children with absent click-evoked ABR at instrumentation limits still had average aided thresholds better than 60 dB 6
• Neonatal ABR has only 42% sensitivity for predicting subsequent hearing loss—normal neonatal testing does NOT exclude hearing problems 7
• The diagnostic battery MUST include multiple test modalities (OAEs, tympanometry, frequency-specific ABR, and behavioral audiometry) because no single test provides complete information 3