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  • JCIH High-Risk Registry (1994) → superseded by UNHS (2000, 2007, 2013 statements).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.