Types of Congenital/Early Onset Hearing Loss and Why It Is Important to Know the Difference

1. Early Hearing Detection and Intervention – The Role of the Primary Care PhysicianAAP CME Teleconference, Part IOctober 15, 2003

2. Types of Congenital/Early Onset Hearing Loss and Why It Is Important to Know the Difference Gravel

3. Hearing Loss Characterized broadly by degree, configuration and type, • Degree: amount of hearing loss in relationship to normal auditory function • Configuration: overall ‘shape’ or pattern of the hearing loss as displayed on the conventional audiogram in dB HL as a function of frequency • Type: site (location) of the auditory disorder

4. Normal Borderline (Minimal) Mild Moderate Moderate-severe Severe Profound -10 to 15 dB HL 16 to 25 dB HL 26 to 40 dB HL 41 to 55 dB HL 56 to 70 dB HL 71 to 90 dB HL > 90 dB HL Degree: Categories of HL New York State Department of Health

5. Hearing Loss Characterized broadly by degree, configuration and type, • Degree: amount of hearing loss in relationship to normal auditory function • Configuration: overall ‘shape’ or pattern of the hearing loss as displayed on the conventional audiogram in dB HL as a function of frequency • Type: site (location) of the auditory disorder

6. Configuration:SlopingHigh frequency thresholds >20 dB poorer than low frequency Frequency in Hz Hearing Level (HL) in dB Stach, 1998

7. Hearing Loss Characterized broadly by degree, configuration and type, • Degree: amount of hearing loss in relationship to normal auditory function • Configuration: overall ‘shape’ or pattern of the hearing loss as displayed on the conventional audiogram in dB HL as a function of frequency • Type: site (location) of the auditory disorder

8. Types of Hearing Loss:Conductive • Reduction of air-conductive sound delivered to the normal cochlea during transmission through a disordered outer ear and/or middle ear • Sound reaching cochlea attenuated to some degree (in OME or debris ~25 dB HL; in complete atresia, maximally ~60 dB HL) • Excellent speech perception when incoming acoustic signal is sufficiently intense

9. Type of Hearing Loss: Sensory • Damage to outer or outer and inner hair cells of the cochlea • Differing impact on speech perception depending on degree and configuration of hearing loss • Multiple audiometric configurations • Any degree of hearing loss

10. Types of Hearing Loss:Mixed • Bothsensory component and overlying conductive component • Example: child with sensory loss who experiences OME

11. Types of Auditory Disorders: • Neural • Outer ear, middle ear and cochlea (OHCs) intact • Deficit in neural transmission (auditory neuropathy) • Central • Conductive, sensory & neural pathway intact • Processing deficit at higher levels of the central nervous system

12. Hearing Loss: Characterized by Ear(s) Affected • Bilateral • Unilateral (in one ear only)

13. What are the major genetic and environmental causes of congenital hearing loss ?Vohr

14. Characteristics of Children with Hearing Loss Site Rate Well Baby Nursery 1 per 1000 NICU 10 per 1000 Total population 2-3 per 1000 # infants ident annually US 8,000-16,000 Average career pediatrician 12 patients

15. JCIH Risk Factors for Infants birth to 28 days • Any illness requiring admission to the NICU for > 48 hours. • Stigmata associated with a syndrome known to include SNHL or conductive HL • Craniofacial anomalies including the pinna and ear canal • In utero infections including CMV, herpes, toxoplasmosis and rubella • Family history of permanent HL

16. Most Common Specific Environmental Risk Causes CMV > 1 risk factor Meningitis Perinatal Asphyxia Prematurity < 1500 g Ototoxic medications

17. Some Infants pass their hearing screen and have late onset hearing loss Some of these infants have a risk factor and some have no risk factor known to the family or physician.

18. Risk indicators from 29 d to 2 years of age • Stigmata or Syndrome associated with HL • In-utero infections • Postnatal infections • Neonatal indicators such as ECMO • Neurodegenerative disorders • Head trauma • Recurrent or persistent OM

19. Risk Indicators obtained from the family • Parent or caregiver concern regarding hearing, speech, language, or developmental delay (parent concern has been shown to be a good predictor). • Family history of permanent HL in first or second degree relatives with onset by 30y or age.

20. Causes of Permanent Hearing Loss in 100 Infants 50% Environmental 50 50% Genetic 30% syndromes (>300) 30 20% >75 genes ident 20 ½ are GJB2 – Connexin 26

21. Genetic Causes Single gene Connexin 26 Gene + environment Mitochondrial + ototoxic Gene + gene Gene + other gene

22. The Connexin 26 Gene • It is estimated that 50-80 % of all autosomal recessive congenital deafness may to due to mutations in th3e Cx-26 gene on chromosome 13q11-q12 • The Cx gene produces a gap junction protein expressed between the outer hair cells and supporting cells and is involved with auditory transduction. • The estimated carrier frequency in the general population is 1 in 31. (Estivill et al, 1998)

23. Genetic Testing • Obtaining an adequate sample for DNA testing is now quite easy • Bilateral buccal smears with a Q tip provide adequate genetic material for testing. • The follow-up genetic counseling is key to the success of genetic testing.

24. New technologies used in hearing screening Gravel

25. Otoacoustic Emissions (OAE) • By-product of the active processing of healthy OHC • Recording of an OAE • Indicates healthy OHCs (cochlea) • Presence highly correlated with normal hearing sensitivity or no greater than a mild hearing loss • Sensorineural hearing losses of greater than about 30 dB HL generally result in absent OAE. • Since recording OAE requires normal forward and backward transmission of energy to and from the cochlea, conductive hearing loss associated with middle or outer ear abnormality can result in absent OAE

26. Types of OAE • Spontaneous OAEs • Evoked OAEs • Transient OAE (TEOAE, TOAE, or click-OAE: COAE) • Distortion Product (DPOAE)

27. TEOAE • Elicited by transients or brief stimuli • Clicks: rapid onset, broadband stimulus containing energy from low through high frequencies (i.e., across speech frequency range) • Tone bursts: more frequency-specific

28. Distortion-Product OAE (DPOAE) • Occur as a result of nonlinear processes of the cochlea • When 2 tones are presented to the cochlea, “distortion” occurs in the form of other tones (harmonics) that are not present in the 2 eliciting tones

29. EOAE Advantages: Quick Inexpensive Frequency-specific Identifies cochlear and conductive losses: mild-mod? Pass-refer screening devices available EOAE Disadvantages: Sensitive to ear canal and middle ear conditions Sensitive to noise (internal & external) Cannot identify neural disorders including auditory neuropathy High fail rates in some programs. Screening Technologies - NeonatesEvoked Otoacoustic Emissions

30. Device Options for OAE Screening Types • Handheld • Portable screening devices • PC-based hybrids • PC-based clinical systems

31. Auditory Brainstem Response (ABR) • Recording (through surface electrodes) of the micro-volt electrical activity generated by the cochlea and transmitted by the auditory nerve and brainstem pathways in response to brief clicks. • Clicks produce a synchronized response from neural fibers; a tracing of the response is a series of waves

32. ABR Advantages: Identifies cochlear, conductive and neural losses: ? mild-mod. Pass-refer screening devices. Some test both ears simultaneously. Relatively insensitive to transient ear canal, middle ear & external noise. ? Lower fail rate than OAE ABR Disadvantages: Test time Disposable costs Infant state/myogenic artifact Requires electrode prep, placement & removal Click can miss unusual configurations of HL Screening Technologies – NeonatesScreening (Automated) Auditory Brainstem Response (SABR or AABR)

33. Examples of screening ABR technology

34. OAE + ABR Advantages: Low fail rate Depending on test order, identifies cochlear, neural and conductive losses Reduced effects of noise Pass-refer screening devices available for both technologies OAE + ABR Disadvantages: Time Equipment and disposable costs In-Hospital Screening:Two Technology Protocol

35. Why is diagnostic confirmation by an audiologist skilled in evaluating infants and young children important?Vohr

36. A failed hearing screen may be a false positive or an actual fail. These 2 findings need totally different management. Therefore, an accurate diagnosis of normal hearing, SNHL, auditory neuropathy or conductive loss is important as soon as possible to minimize parental stress and to decrease the time interval between screen fail and starting treatment. Parents of late identified children have feelings of guilt and frustration.

37. Early Identification of Hearing Loss is Important because • Delayed identification, even of mild HL results in language delays developmental skill delays, and behavior problems. • Subsequent delays in literacy, and academic performance

38. Reading Comprehension Scores of Hearing and Deaf Students Grade Equivalents Age in Years Deaf Children in America 1986

39. Unilateral or Mild Loss • 50% of children either repeat a grade or need resource support in school • Increased behavioral and linguistic problems compared to hearing controls. Bess F, Pediatrics 1984

40. Early “Early Intervention” for Hearing Loss is Important because • There are dramatic benefits associated with early identification and intervention for hearing loss before 6 months of age. • Children identified and receiving services < 6 m have larger vocabularies, better comprehension and better expressive language than children identified > 6 m.

41. Are Interventions Available to Improve Outcome? White - ­ language scores of sev to profound (14 vs 26 m) Apizzo - better language scores at 4 if ident <2 m Moeller - 100 D/HH children with early ident - better outcomes Yoshinago-Itano - better scores at 36 m if ident <6 m Early “Early Intervention” is better !!!!

42. AAP & JCIH Recommendations Components of EHDI Programs in the US • Universal Newborn Hearing Screening< 1 m • Effective Tracking and Follow-up as a part of the Public Health System • Appropriate and Timely Diagnosis of the HL < 3m • Prompt Enrollment in Appropriate EI < 6m • All infants will have a medical home

43. Importance of Diagnostic Audiologic Confirmation of Hearing Loss Gravel

44. Gravel, 2000; Gravel & Hood, 1998

45. “Audiologists should have experience with the assessment of infants & children with HL and the knowledge and equipment necessary for use with current pediatric assessment methods”. “Facilities that lack the expertise or equipment for assessing infants & children should establish consortial arrangements with those that do”. Pediatric Working Group, 1996

46. What are the components of the medical home work-up for children with congenital hearing loss?Vohr

47. EHDI and the Medical Home Hospital Screening Audiology Parent Groups Mental Health Primary Provider Child/Family ENT 3rd Party Payors Deaf Community Interpreters EI Therapists Genetics Deaf Services

48. The Medical Workup • Complete prenatal & perinatal hx • Family Hx of onset of HL < age 30 • Physical for stigmata, ear tabs, cleft palate, cardiac, skeletal, microcephaly • Refer to ENT / CT of temporal bones • Refer to Genetics and Opthalmology • Other: CMV, EKG

49. What are some of the questions to ask ? • Antenatal history- maternal illness during the pregnancy or delivery • Neonatal complications, prematurity, jaundice, asphyxia, assisted ventilation, ECMO

50. Examination for Causes • Evaluate for dysmorphic features, minor and major stigmata and syndromes • Other anomalies – visual, facial, endocrine, cardiac, kidney, hair, and skin • Particular attention to the head and neck. HL may be associated with abn. pinna, atresia or stenosis of the ear canal, ear tags, and bony growths in the ear canal. • Cleft lip and palate may have middle ear fluid