How should an 8‑month‑old infant with left‑ear hearing loss be evaluated and managed?

Evaluation and Management of an 8-Month-Old with Left Ear Hearing Loss

An 8-month-old infant with unilateral left ear hearing loss requires immediate referral to a pediatric audiologist for comprehensive diagnostic evaluation including ABR testing, otoacoustic emissions, and tympanometry, plus referral to a pediatric otolaryngologist for complete diagnostic assessment to determine etiology—even though unilateral hearing loss typically does not impair language development, early identification of the underlying cause is critical as it may indicate progressive disease, syndromic conditions, or treatable pathology. 1

Immediate Diagnostic Workup

Comprehensive Audiological Evaluation (by 3 months of age or immediately at 8 months):

• Frequency-specific ABR testing using air-conducted tone bursts to determine hearing thresholds across frequencies 1, 2
• Click-evoked ABR with both condensation and rarefaction stimuli to assess neural function 1, 2
• Otoacoustic emissions (OAE) testing—distortion product or transient evoked—to evaluate cochlear outer hair cell function 1, 2
• Tympanometry using 1000-Hz probe tone (age-appropriate for infants) to assess middle ear status and rule out conductive overlay 1
• Detailed child and family history focusing on risk indicators for hearing loss 1, 2

Essential Specialist Referrals:

• Pediatric otolaryngologist for complete diagnostic assessment—this is essential for all young children with sensorineural hearing loss to determine etiology, identify related physical conditions, and provide treatment recommendations 1, 3
• Genetics evaluation and counseling to identify specific causes (GJB2/connexin-26 mutations are most common), assess for syndromic hearing loss, provide prognosis information, and counsel on recurrence risk 4, 3
• Speech-language pathologist for baseline assessment even with unilateral loss 3

Critical Etiologic Evaluation

Risk Factor Assessment—Review for High-Risk Indicators:

• Family history of permanent childhood hearing loss 1
• NICU stay >5 days or exposure to ototoxic medications (gentamicin, tobramycin), loop diuretics (furosemide), or need for ECMO 1
• In utero infections: CMV (most important), herpes, rubella, syphilis, toxoplasmosis 1
• Craniofacial anomalies: ear tags, pits, temporal bone abnormalities 1
• Syndromes associated with hearing loss: Waardenburg (white forelock), Usher, Pendred, neurofibromatosis 1
• Hyperbilirubinemia requiring exchange transfusion 1
• Head trauma or temporal bone fracture 1

Genetic Testing Panel:

• GJB2, GJB6, GJB3 (connexin genes—most common cause of nonsyndromic hearing loss) 4
• SLC26A4 (Pendred syndrome/enlarged vestibular aqueduct) 4
• Mitochondrial genes 4

Imaging Studies:

• High-resolution CT of temporal bones is the imaging modality of choice for evaluating congenital otic capsular dysplasias, inner ear malformations, and temporal bone abnormalities 5
• Contrast-enhanced MRI is preferred if inflammatory, neoplastic, or neural pathology is suspected, or if there is documented acute hearing loss 5

Management Approach

For Unilateral Sensorineural Hearing Loss:

• Unilateral hearing loss fortunately has no impact on language development and children typically achieve normal speech milestones 6
• However, studies show that early-onset severe unilateral hearing loss may be associated with deficits in auditory and psycholinguistic skills and school performance—31% of children with unilateral hearing loss have scholastic or behavioral problems 7
• Amplification is generally not required for unilateral loss, but assistive listening devices (FM systems) may benefit school-age children in noisy classroom environments 8

Critical Monitoring Requirements:

• Serial audiometry every 6 months to monitor for progression—certain genetic causes (enlarged vestibular aqueduct, specific connexin mutations) are associated with progressive hearing loss 1, 4
• Contralateral ear monitoring is essential—if the good ear develops hearing loss, immediate intervention becomes critical 1
• Middle ear surveillance with tympanometry—any middle ear effusion in the good ear must be promptly treated as it would compound the existing unilateral loss 1, 3
• Developmental monitoring for speech, language, and academic performance 1

Common Pitfalls to Avoid

Never adopt "watchful waiting" for unilateral hearing loss without completing the diagnostic workup—the etiology may reveal:

• Progressive hearing loss requiring closer monitoring 4
• Syndromic conditions with other organ system involvement requiring additional screening 1
• Treatable causes (chronic otitis media, cholesteatoma, temporal bone abnormalities) 1
• Risk for bilateral progression 7

Do not assume unilateral loss is benign—while language development is typically normal, these children are at risk for educational difficulties and require ongoing developmental surveillance 7

Ensure genetic counseling is offered to all families—over 90% of children with permanent hearing loss are born to parents with normal hearing, and genetic information influences family planning, prognosis, and management decisions 3

Parental Counseling

Provide clear, evidence-based information:

• Unilateral hearing loss typically does not delay speech and language development 6
• The underlying cause must be identified to assess prognosis and need for intervention 1, 3
• Regular monitoring is essential to detect progression or contralateral involvement 1, 4
• Educational accommodations (preferential seating, FM systems) may be beneficial as the child enters school 8, 7