Pediatric Hearing Loss — Key Vocabulary

Learning Outcomes

• 7.1 Infant Responses & Sleep Levels
  • Recognize startle, APR, motor, and vocal changes as auditory responses.
  • Understand how alert, drowsy, light- & deep-sleep states modulate response probability.
• 7.1 Early Hearing Detection & Intervention (EHDI)
  • Know the 3 components: birth-admission screening, prompt diagnostic follow-up, intervention ⩽6 mo.
  • Grasp goals: identification ⩽3 mo, amplification/therapy ⩽6 mo, language outcomes near age peers.
• 7.2 Test Approaches Across Ages
  • Match BOA/COR/VRA/OAE/ABR/ASSR/Play/OCA to developmental stage.
  • Apply the cross-check principle: behavioral ↔ physiologic ↔ developmental consistency.
• 7.3 School Screening Programs
  • Specify equipment, calibration, acoustic environment, referral & follow-up procedures.

Historical Context & Prevalence

• Antiquity: hearing loss once justified infanticide; civil rights (marry, own property) restricted until ≈400 C.E.
• Modern prevalence
  • Newborn UNHS: 1\text{ infant}/1000 severe–profound bilateral HL.
  • Overall 0–18 y: 3.1\% have HL ≥1 ear.
  • Birth statistics: 4\times10^{6} U.S. births / yr → 4{,}000–8{,}000 infants w/ permanent HL.
• Trend: profound losses ↓, mild/unilateral ↑; mild loss produces greater educational impact than presumed.

Justification & Criteria for Newborn Screening

• WHO/JCIH criteria for any neonatal screen:
  1. Sufficient prevalence.
  2. Earlier detection vs routine care.
  3. Immediate diagnostic availability.
  4. Accessible treatment.
  5. Documented benefit of early ID – satisfied for HL.
• Cost efficiency
  • HL ranks 3rd among U.S. chronic childhood conditions.
  • \text{Cost/case}{\text{UNHS}} \approx\text{cost/case}{\text{PKU}} when prevalence is considered.
  • Hundreds of millions saved/year via early language & educational gains.

Key Organizations & Policy Milestones

• Apgar Score (1953): Appearance, Pulse, Grimace, Activity, Respiration (0–10 at 1, 5, 10 min). Low score ⇒ ↑HL risk.
• JCIH High-Risk Registry (1994) → superseded by UNHS (2000, 2007, 2013 statements).
  • High-risk misses ≥50 % of congenital HL; still used where UNHS absent; guides later surveillance.
• Stakeholders: AAA, ASHA, AAP, AG Bell, CED, state EHDI programs.

Neonatal Screening Techniques

• Otoacoustic Emissions (OAE)
  • Quick, \le 30 dB cochlear integrity check; fails w/ minimal middle-ear dysfunction.
  • DPOAE preferred (500–4000 Hz info).
  • Limitation: misses retro-cochlear & AN/AD.
• Auditory Brain-stem Response (ABR)
  • Click or CE-chirp stimulus, newborn norms corrected for gestational age.
  • Automated ABR devices: disposable electrodes/earcups, tech-friendly, portable.
  • Lacks frequency specificity; threshold ceiling ≈ 80\;\text{dB HL}.
• Combined / 2-Step Protocols
  • OAE pass → done; OAE fail → ABR.
  • Concurrent OAE+ABR maximizes sensitivity (Hall et al., 2004).
  • Debate: ABR-only pass after OAE fail may miss early OHC pathology → risk of progressive loss.
• Auditory Neuropathy/Dys-Synchrony (AN/AD)
  • Presents: present OAE/CM, absent ABR & MEMR.
  • Necessitates ABR inclusion to avoid false negatives in OAE-only sites.

Operational Challenges & Support Personnel

• 4\times10^{6} births ⇒ massive staffing need; utilize trained techs under audiologist supervision.
• Tech duties: equipment care, screening operation, data logging, parent comms.

Pediatric Hearing Evaluation (General)

• AAA 2012 guideline: integrate
  • Behavioral thresholds (gold standard)
  • Electrophysiology (ABR/ASSR)
  • Physiologic (OAE, immittance)
  • Developmental milestones & history.
  • Cross-check principle (Jerger & Hayes, 1976).

Subjective Observation & Case History

• Observe parent-child interaction, gait, motor skills, communicative intent.
• Case history domains: prenatal, perinatal, postnatal events; otitis media; NICU stay; family HL; language at home.

Objective Bedside Tests

• Immittance
  • Tympanometry (226 Hz; 678/1000 Hz probe for <6 mo).
  • Acoustic reflex (ipsi/contra, pure-tone & BBN).
  • Useful for type of loss & cross-check; movement/crying can invalidate.
• OAE – first due to maturity-independent & fast.

Behavioral Observation Audiometry (BOA) 0–6 mo

• Two-examiner setup; look for APR, startle, limb freeze, cessation/change of sucking.
• Minimum Response Levels (MRL) > adult thresholds; see Table:
  • 0$–$4\,\text{mo}: voice 45\;\text{dB HL}, warble 70\;\text{dB HL}.
  • 20$–$24\,\text{mo}: speech 10\;\text{dB HL}, warble 25\;\text{dB HL}.

Sound-Field & Visual Reinforcement (6 mo–2 yr)

• Localization Development
  • 3 mo – horizontal head jerk
  • 5 mo – horiz → vertical
  • 6 mo – arc
  • 8 mo – direct line.
• COR (Conditioned Orientation Reflex): tone + lighted doll pairing.
• VRA: any animated/light reinforcer; effective ≥6 mo corrected age; ear-specific if insert phones tolerated.
• Signal considerations: warble or narrow-band noise; beware broad-spectrum misleading & wide filter skirts.

Testing 2–5 Years

• Transition to earphone pure-tone thresholds; warble or pulsed tones; rapid pace.
• Speech Audiometry
  • SRT by picture/ body-part pointing, Ling Six sounds.
  • Gap between SDT & SRT can enlarge in sloping losses.
  • Six-Sound meaning: /a,u,i/ ≤1000 Hz; /ʃ/ ≈2000 Hz; /s/ ≈4000 Hz.
• Play Audiometry (CPA)
  • Block-in-bucket, ring-stack, peg-board; motivation & reinforcement critical.
  • Keep surplus tokens to avoid extinction.
• Operant / Tangible Reinforcement (TROCA)
  • Switch-press → candy/token via feeder; requires many trials, series wiring prevents false reward.

Electrophysiological Threshold Estimation

• ABR: sleep/sedation OK; begin binaural to capture better ear; follow with ears separately.
• ASSR: extends beyond 80\;\text{dB HL}; complements ABR for severe/profound estimation.
• Objective tests confirm type/degree when behavior unreliable; do not delay amplification while awaiting perfect behavioral data.

School Hearing Screening Programs

• ∼>5\% of public-school children have HL at any time (conductive peaks in winter).
• Equipment: annual electroacoustic calibration; daily listening checks; quiet room (<35\;\text{dBA} ideal).
• AAA 2011 Protocol (Summary)
  • Grades: Pre-K, K, 1, 3, 5, 7/9.
  • Pure-tone 1000,2000,4000\,\text{Hz} @ 20\;\text{dB HL} (pulsed); immediate rescreen if fail.
  • Tympanometry as 2nd stage or jointly in Pre-K–1; fail if width>250 daPa, pressure <-200 daPa, or compliance <0.2\,\text{mmho}.
  • OAEs used only when PT not developmentally possible (<3 y).
  • Refer if fail repeat in 8$–$10 wk or immediate if obvious loss.
• Immittance-only screening detects early otitis media; pulsed-tone reflex ↑ sensitivity.

Reliability & Tetrachoric Analysis

• Definitions
  \text{Sensitivity}=\frac{TP}{TP+FN}
  \text{Specificity}=\frac{TN}{TN+FP}
• Tetrachoric table (Newby, 1948): Cells A (TP), B (FP), C (FN), D (TN); balance criteria to minimize B & C while respecting resources.

Non-Organic HL & Unilateral Loss

• School screens may flag deceptive or psychogenic losses; alert clinicians use Stenger, consistency checks, parental insight.
• Unilateral or minimal losses often overlooked; yet linked to academic under-performance.

Clinical & Ethical Implications

• Early ID → neuroplastic language acquisition; delays cost society & families academically, socially, financially.
• Maladaptive parenting, SIDS, enzymatic disorders (biotin deficiency) biologically linked to HL → urgency of EHDI.
• Support personnel expand reach but must be supervised; data management, counseling integral.

Summary: Procedure Suitability & Success Probability

• Speech sounds (4–8 mo) – good.
• COR/VRA (6 mo–2 y) – good.
• Vocal imitation (<1 y) – fair.
• Play (2–6 y) – good.
• Operant (2–5 y) – good.
• Noisemakers (<3 y) – fair.
• Pure-tone (>3 y) – good.
• AEP/OAE/Immittance (all ages) – very good.

Key Numerical / Statistical References

• UNHS prevalence: \approx1$–$2/1000 severe–profound; up to 4/1000 incl. mild/unilateral.
• Apgar risk link; score range 0–10; low (<7) → ↑SNHL risk.
• BOA MRLs (warble): 0$–$4\,\text{mo}=70 dB HL → 20$–$24\,\text{mo}=25 dB HL.
• Tympanometric fail: width >250 daPa OR <-200$$ daPa pressure.

Connections & Real-World Relevance

• Public-policy: EHDI data reporting drives federal/state funding.
• Educational: IDEA mandates FAPE; early amplification underpins LSL or total-communication curricula.
• Technological: portable automated ABR/OAE units democratize rural screening.
• Ethical: balance over-referral anxiety vs under-identification harm.
• Practical: parent counseling, language stimulation, hearing-aid fitting must not await perfect thresholds.