What is the difference between BERA (Brainstem Evoked Response Audiometry) and other auditory assessments, such as OAE (Otoacoustic Emissions), in diagnosing hearing impairment in infants with congenital syphilis?

BERA vs OAE in Diagnosing Hearing Impairment in Infants with Congenital Syphilis

Direct Answer

For infants with congenital syphilis, BERA (Brainstem Auditory Evoked Response/ABR) is the superior diagnostic test and should be used preferentially over OAE (Otoacoustic Emissions), as OAE cannot detect auditory neuropathy or neural hearing loss—conditions to which these infants are particularly vulnerable. 1

Key Differences Between BERA and OAE

What Each Test Measures

BERA (ABR):

• Detects neurologic responses to auditory stimuli by placing electrodes on the infant's head, assessing the entire auditory pathway from the cochlea through the brainstem 1
• Can identify both cochlear and retrocochlear (neural) hearing loss 2
• Provides ear-specific, frequency-specific results that create a map similar to an audiogram 1

OAE:

• Measures acoustic emissions generated within the cochlea itself using a probe in the ear canal 1
• Only assesses outer hair cell function in the cochlea 3
• Cannot detect auditory neuropathy/dyssynchrony because the test does not assess neural function beyond the cochlea 4, 3

Critical Limitation of OAE in Congenital Syphilis

The fundamental problem: OAE will miss neural hearing loss entirely 4, 3. Since infants with congenital syphilis are at specific risk for neural conduction disorders affecting the eighth nerve or auditory brainstem pathway, OAE screening alone is inadequate 3.

Why This Matters for Congenital Syphilis

Risk Profile

Infants with congenital syphilis have specific vulnerabilities:

• Neurosyphilis can cause central nervous system infection affecting auditory pathways 5
• Congenital syphilis is a known cause of progressive sensorineural hearing loss 6
• These infants require comprehensive evaluation beyond simple cochlear screening 1

CDC Guidelines for Evaluation

For infants with proven or highly probable congenital syphilis, the CDC explicitly recommends "auditory brain stem response" as part of the clinical evaluation 1. This recommendation appears in the context of comprehensive workup including:

• CSF analysis
• Complete blood count
• Long-bone radiographs
• Auditory brainstem response 1

Practical Testing Algorithm

Initial Screening (Birth)

• All newborns, including those with congenital syphilis, undergo universal hearing screening 4
• However, infants with risk factors (including congenital infections like syphilis) should receive ABR screening rather than OAE alone 4, 3

Diagnostic Evaluation (By 3 Months)

If screening is failed or if congenital syphilis is diagnosed:

• Comprehensive audiological evaluation must include diagnostic ABR with frequency-specific testing 4
• The evaluation should include air-conducted tone bursts, click-evoked ABR with both condensation and rarefaction stimuli 4
• OAE can be included as supplementary information but cannot replace ABR 4

Ongoing Surveillance

• All children with congenital syphilis require longitudinal hearing screening regardless of initial results 6
• At least one diagnostic audiology assessment should occur by 24-30 months of age 4
• This is critical because syphilitic hearing loss can be progressive 6

Common Pitfalls to Avoid

Pitfall #1: Relying on OAE Alone

Never use OAE as the sole diagnostic test for infants with congenital syphilis. OAE will provide false reassurance if neural hearing loss is present 4, 3.

Pitfall #2: Assuming Normal Neonatal ABR Means No Future Risk

Even asymptomatic infants with serologic evidence of syphilis who have normal neonatal ABRs may develop hearing loss later 7. One study of 75 asymptomatic neonates with syphilis found all had normal ABRs initially 7, but this does not eliminate the need for ongoing surveillance given the progressive nature of syphilitic hearing loss 6.

Pitfall #3: Accepting "Pass" on Repeat OAE After Initial Failure

Repeated screening increases the likelihood of obtaining a pass outcome by chance alone when statistical probability is used for pass/fail decisions 3. If an infant with congenital syphilis fails initial screening, proceed directly to diagnostic ABR rather than simply repeating OAE 4.

Sedation Considerations

The infant must remain quiet during ABR testing, which often requires sedation 1, 4. This is a practical limitation but does not diminish the necessity of the test. Plan accordingly and counsel parents that sedation may be needed for accurate diagnostic ABR 4.

Evidence Quality Note

The strongest guideline evidence comes from the CDC's 2010 STD Treatment Guidelines 1 and the American Academy of Pediatrics recommendations 1, 4, which consistently prioritize ABR over OAE for high-risk infants. Research evidence is limited—one systematic review found no prospective studies documenting hearing outcomes in treated congenital syphilis 6—which reinforces the importance of following guideline-based surveillance protocols.