1. NIHL Part 2

2. Requirements for a diagnosis of NIHL
R1 High frequency impairment (single HTL 10dB > at 3,4 or 6 than at 1 or 2) R2 Noise emission level accumulative to 100dB (A) NIL for sufficient number of years at 85dB (A). Impact noise R3 Identifiable high frequency notch or bulge in 3 – 6kHz range 10dB or more

3. Modifying factors Compatibility with age and exposure
Borderline cases – probability tests
Complications – conductivity, asymmetry
Asymmetry – if noise was unilateral
Better HF ear shows NIHL – yes
One does and other borderline – probably yes
Not much difference and only 1 ear shows NIHL – borderline
Only worse – unlikely

4. Additional Risk Factors - introduce impurities in dx
Other employment noise
Medical conditions of the ear including surgery
Head injury
Ototoxicity
Diabetes and peripheral vascular disease
Uncontrolled hypertension ???
Social exposure
Family history
Firearms/Exposives
Untoward acoustic events
Other causation of unknown origin

5. Asymmetry – supportive or not?

6. Supportive of NIHL or not?

7. Supportive
Very early NIHL
R1 and R3 both minimally met

8. Supportive of NIHL or not?

9. Not supportive/borderline
Left is supportive
Right is NOT supportive. Why not?
Not much difference in the HF and one ear has a significant notch or bulge and the other has little or no trace.
Does not currently support but might indicate developing NIHL
REVIEW 12/12

10. Supportive of NIHL or not?

11. Supportive
R1 and R2 both met Worth investigation if more noise on left side at work

12. Supportive of NIHL or not?

13. Supportive
Asymmetrical hearing impairment. Apply “Appendix A, note 11”
R1 and R3 supported in the better high frequency ear
Probability “more likely than not”

14. Supportive of NIHL or not?

15. Not supportive
Asymmetrical hearing impairment. Apply “Appendix A, note 11” Only the worse ear shows NIHL. Only a possibility not a probability of NIHL. Possibility is <50%. Therefore on balance of probability not NIHL.

16. Asymmetry All prior examples assume symmetrical exposure to noise
Apparent explanation should be considered:
Firearms exposure
Acoustic shock to one side
Noise biases towards one side
Other employees have same finding
Asymmetrical NIHL IS supported if there is an “apparent explanation”

17. Screening outcome codes
HSE Categorisation Scheme Category Action
1. ACCEPTABLE HEARING ABILITY
Hearing within normal limits None
2.MILD HEARING IMPAIRMENT
May indicate developing NIHL Warning
3. POOR HEARING
Suggests significant NIHL Referral
4. RAPID HEARING LOSS
Reduction in hearing level of 30 dB or more,
within 3 years or less Referral

18. HSE Screening criteria
Not a sensitive criteria to recognise NIHL especially in early critical stages
Not sensitive to small year on year changes – critical identifier of NIHL risk (30db vs 10dB)
Reliant on entire Auditory pathway
Bone Conduction Audiology is required to identify NIHL
BC establishes cochlear and retrocochlear conditions
Therefore BC testing is a definitive assessment for NIHL providing criteria for dx are met

19. Published on line (new)
Noise Induced Hearing Loss – An Examination of the Methods of Assessment in a Cross-sectional Study of 87 Industrial Workers Clinical Otolaryngology November 2017

20. Abstract
Objectives
The surveillance of noise-induced hearing loss (NIHL) according to the Health & Safety Executive (HSE) differs from the medico-legal criteria used to assess NIHL. Our study compares the two systems and proposes a novel method of simplifying the medico-legal criteria and applying it to ascertain noise-induced hearing loss.
Design
The anonymised audiograms of a group of 87 industrial workers from a single site were analysed with both methods.

21. Results
The comparison showed approximately one-third of the workers assessed in this study had their noise-induced hearing loss underestimated by the HSE criteria. The majority of these individuals were over 40 years of age.
Conclusions
The HSE criteria for noise-induced hearing loss needs review and re-alignment with the medico-legal criteria to address the discrepancy between the two systems.
This article is protected by copyright. All rights reserved

22. IDC Diagnostics Categories (IDC 1-5)
Normal versus age
Predominantly medical
Mild NIHL notch/bulge 10 – 30dB when extrapolated
Significant NIHL notch/bulge > 30dB
Deterioration – notch/bulge increases by 10dB or more. Requires experienced consideration of audiogram over time

23. Questions?
Thank you!

24. NIHL Quiz
4 audiograms plus answer sheet Which diagnosis A- D fits which audiogram 1-4 Which ears supports NIHL (R1 and R3) Which require urgent medical referral (yes or no) Mark yourself out of 12