Characteristics of Congenital Hearing Loss

1. Characteristics of Congenital Hearing Loss Barbara S. Herrmann, Ph.D. CCC-A Audiology Department Massachusetts Eye and Ear Infirmary Harvard Medical School

2. Examine outcomes of UNHS For one metropolitan nursery: • What types/degrees of hearing loss are being identified in newborns referred by UNHS • What happens to those hearing losses over the first few months/years

3. My UNHS Background:

4. Data presented: • From UNHS program at Massachusetts General Hospital • Initiated NICU screening in 1981, UNHS in 1997 • Follow-up evaluation at Massachusetts Eye and Ear Infirmary Audiology Department scheduled within 1 to 3 weeks of hospital discharge • If hearing loss, usually next evaluation at 4 months of age

5. UNHS Flow in Massachusetts Discharge Notify Parent Pediatrician Pass Hearing Screen Audiologist Supervise Notify Parent Pediatrician Make F/U Appt Keep F/U Appt Refer EBC Phone Call to Parent Pass DPH DPH Parent Liason Refer

6. 5 Critical Elements for Success 1 Discharge Notify Parent Pediatrician Pass Hearing Screen Audiologist Supervise 2 Notify Parent Pediatrician Make F/U Appt Keep F/U Appt Refer EBC 3 Phone Call to Parent Pass 4 DPH DPH Parent Liason Refer

7. Screening Protocol at MGH • ALGO Infant Hearing Screeners (ALGO I to ALGO 3i) • Audiologists or Technicians • 35 dB HL shaped-click at 37/sec over 25 msec analysis time. • Custom ear couplers. • Electrode montage; Vertex (+), Nape (-), Forehead (ground). • Single Screen

8. All MGH Nursery: 2000 to 2005N=21,613 babies

9. MGH Statistics by Nursery Level MGH Level 1 N=19,252 MGH Level 3 N=1,371

10. Follow-up between 1 and 4 weeks after discharge

11. AER Estimated Audiogram Bone-Conduction Left Ear Threshold Right Ear Threshold

14. First follow-up test N=393 of 455 refers (12% transferred or lost to follow-up) Normal hearing = AER thresholds of 20 dB HL or better

15. First follow-up by refer type Bilateral Refers Unilateral Refers

16. Type of Neonatal Hearing Loss Percent of Babies with Hearing Loss ( N=135) 60% bilateral loss; 40% unilateral loss Incidence of Hearing Loss overall - 0.6% Incidence of sensorineural loss – 0.15%

17. Degree of Hearing loss: • Classified by threshold at 2000 Hz toneburst • Classification rules: • Normal: 20 dB HL or better at 2000 and 4000 Hz • Borderline: 25 db HL • Mild: 30 to 40 dB HL • Moderate: 45 dB to 65 dB HL • Severe: 75 to 85 dB HL • Profound: 90 dB HL or greater

18. No response at 102 dB HL Range of thresholds for each degree Borderline Mild Profound Moderate Severe

19. Degree of Hearing Loss: all loss ears 23% 28% 32% 5% 12% N=215 ears 51% of refers have 2000 Hz thresholds between 25 and 40 dB HL

20. Degree of Hearing Loss: by type 20% 20% 21% 2% 12% 2% 10% 7% 3% 3% 65% conductive/unknown type 35% known sensorineural component N=215 ears

21. Further details: • Unknown or type not determined • Conductive hearing losses • Sensorineural / mixed hearing loss • Insight into current issues

22. Unknown/ Type not determined

23. Degree of loss for Unknown/ Type not determined 56% 20% 18% 3% 3% N=66 ears

24. Right ear Left ear Primarily symmetric

25. Conductive hearing loss Right masked bone

26. Conductive hearing loss Conductive hearing loss 10% 46% 41% 3% N=71 ears

27. Again, primarily symmetric Right ear Left ear

28. Conductive and Unknown ears similar, so have grouped them 20% 20% 21% 2% 12% 2% 10% 7% 3% 3% 65% of all loss are conductive or unknown origin: 41% of those are mild or better

29. What have we learned • About 60% of ears with conductive or type not determined hearing loss identified within 1 month of newborn screen have mild or borderline degree of loss. • Most of the babies have similar degrees of loss in each ear

30. Sensorineural / Mixed Losses

31. 20% 36% 8% 9% 28% N=76 ears Sensorineural / Mixed Loss Ears

32. Again, mostly symmetric

33. What have we learned • 66% of ears with sensorineural hearing loss identified within 1 month of newborn screen have moderate hearing losses or better. • 30% of sensorineural hearing loss identified by UNHS have hearing thresholds better than 40 dB HL

34. What happens over time…. • Infants scheduled for another AER evaluation three months after initial test • After that usually seen at 3 month intervals using behavioral audiometry • Many with borderline hearing do not keep appointment • Have re-evaluation data for 65 of 135 infants

35. Sensorineural / Mixed Losses 46% 82% 26% 22% 7% 9% 9% N=65 babies Most conductive losses resolve to normal within 3 months Most sensorineural loss do not change

36. Questions that have arisen in UNHS • Are we identifying mild losses with ABR? • What about unilateral refers with bilateral loss? • Will any screening technique catch all losses? • Should we follow unilateral refers?

37. 20% 36% 8% 9% 28% N=76 ears Are we identifying mild losses with ABR?

38. Yes Bilateral Refer Bilateral Refer First follow-up at 2 days, now 18 months hearing stable First follow-up at 3 days, now 7 years hearing stable

39. What about unilateral refers with bilateral loss? 3 cases of sensorineural/mixed loss on first follow-up in this cohort

40. No response left ear at 85 dB HL Case 1 and Case 2 Identified at 3 weeks, now 3 years old Hearing stable Identified at 6 weeks, now 12 months Hearing stable

41. Case 3 Follow-up AER First AER Which was correct – the screen or first follow-up bone?

42. Will any screening technique catch all losses? ABR bilateral refers; present OAEs

43. First follow-up by refer type Should we follow unilateral refers? Bilateral Refers Unilateral Refers

44. Yes Unilateral Refer Age 6 months First Behavioral Age 1 year

45. YES Age 2.6 years Age 3.5 years

46. Things to keep in mind….

47. Fluctuating conductive always an issue in follow-up studies 3 weeks of age 5 months of age

48. Fluctuating conductive always an issue in follow-up studies 5 months of age 8 months of age

49. Fluctuating conductive always an issue in follow-up studies

50. Lots of confusion over earphones….. Voss and Herrmann 2005 ALGO ear coupler has the least variation from baby to baby than any earphone