In the name of GOD

1. In the name of GOD By Dr S.Rabiei

2. HEARING LOSS Dr Sohrab Rabiei By Dr S.Rabiei

3. By Dr S.Rabiei

4. By Dr S.Rabiei

5. Hearing is the transduction of sound (mechanical energy) into neural impulses and the interpretation of those impulses by the central nervous system • Hearing loss can result from a defect at any level in this system. • The proper management of patients with hearing loss requires an understanding of the normal mechanisms. By Dr S.Rabiei

6. EVALUATION OF HEARING LOSS History • Age of patient • Severity of loss • Duration • Onset - rapid vs. gradual (sudden hearing loss is an emergency),constant vs. fluctuating. • Precipitating or exacerbating factors: trauma, noise, drugs,prenatal infection, etc. • Associated symptoms: Vertigo, tinnitus, pain or fullness in the ear, headache • Family history By Dr S.Rabiei

7. Physical • Emphasize the following: • Otologic exam • Systematic otoscopy • Tuning forks to grossly assess hearing and to differentiate conductive vs. sensorineural • Exam of nasopharynx • Neurologic exam • Inspection, palpation, and auscultation of neck • Look for associated anomalies By Dr S.Rabiei

8. Tests • Basic audiogram - all patients • Diagnostic audio, ENG, internal auditory canal, x-rays, and/or CT scan if vertigo present or neural lesion suspected • Electrocochleography if Meniere's suspected • Appropriate blood tests. • All patients with sensorineural hearing loss should have VDRL and FTA-ABS. By Dr S.Rabiei

9. DIFFERENTIAL DIAGNOSIS External ear: • Cerumen impaction • One of commonest causes of sudden hearing loss • Treat by removing wax • External otitis - inflammation and swelling of canal skin • Tumors of external canal • Congenital aural atresia By Dr S.Rabiei

10. DIFFERENTIAL DIAGNOSIS Middle ear • Otitis media • Acute - infectious or serous • Chronic - serous • Must always rule out possibility of nasopharyngeal carcinoma • Tympanic membrane perforation or cholesteatoma • Normal tympanic membrane with conductive hearing loss • Suspect ossicular abnormality: otosclerosis, ossicular dislocation, etc. By Dr S.Rabiei

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12. Sensorineural hearing loss • often associated with poor discrimination out of proportion to degree of pure tone sensitivity loss - this is due to distortion of sound by cochlea or nerve By Dr S.Rabiei

13. Congenital • Hereditary • Isolated sensorineural hearing loss • Normal inner ear • Abnormal inner ear (Scheibe, Mondini-Michelle, etc.) • Hearing loss with associated anomalies • Acquired • Prenatal infection, especially syphilis, rubella, CMV • Prenatal drugs • Birth trauma • Developmental anomaly • Hereditary but delayed onset • Dominant or recessive • Numerous syndromes, some with associated anomalies (example: Waardenburg's syndrome with white forelock, hypertelorism, etc.) By Dr S.Rabiei

14. Acquired • Noise induced - very common • Presbycusis - hearing loss of old age • Head trauma - temporal bone fracture, labyrinthine concussion,central damage • Meniere's disease or syndrome • Luetic hearing loss (syphilis) • Ototoxic drugs • Oval or round window rupture • Idiopathic sudden sensorineural hearing loss • Acoustic nerve tumor • Infections • Otosclerosis • Surgical trauma By Dr S.Rabiei

15. Noise induced - very common • Due to single blast or repeated or prolonged exposure to loud noise (hunting, rock music) • Affects high frequencies first (4 kHz); often progressive • Frequently associated with tinnitus • No known treatment. Counsel patient to avoid noise in future • PREVENTION is key to reducing incidence By Dr S.Rabiei

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17. Presbycusis - hearing loss of old age • Not universal, etiology not known • Central interpretation deficit complicates peripheral sensitivity loss • No known cure • Amplification can help, but hearing aids must be carefully fitted Cochlear distortion and central processing may preclude us By Dr S.Rabiei

19. Meniere's disease or syndrome • Fluctuating hearing loss • Characteristically associated with bouts of vertigo • Anatomically correlated with endolymphatic hydrops • Electrocochleograph (ECOG) frequently shows elevated summating potential • In active phase, glycerol may improve hearing • Treatment • Medical: low-salt diet, diuretics, avoidance of caffeine,anti-vertigo medication, psychological support • Surgical: for selected patients with progressive disease By Dr S.Rabiei

20. Luetic hearing loss (syphilis) • Usually a fluctuating hearing loss - may mimic Meniere's • Treponemas may remain in endolymph after eradicated from other sites in the body. • Treatment - steroids and antibiotics (penicillin) By Dr S.Rabiei

21. Ototoxic drugs • Reversible: aspirin - associated with tinnitus • Permanent: aminoglycosides, anti-neoplastic drugs, etc. • Treat by prevention: • Careful monitoring of blood levels of toxic drugs • Monitor hearing and vestibular function By Dr S.Rabiei

22. Oval or round window rupture • Sudden onset of hearing loss, usually fluctuating, often accompanied by vertigo. Definitive diagnosis can only be made by surgical exploration. • Usually associated with sudden pressure change: flying,Valsalva, scuba diving, sneeze, etc.; but may be idiopathic • Treatment - initially, bed rest for suspected patients. If no recovery, explore and repair leak if found By Dr S.Rabiei

23. Idiopathic sudden sensorineural hearing loss • Sudden hearing loss with no apparent cause • Etiology obscure, could be viral, autoimmune, vascular,or allergic, to name a few suspected causes • Diagnostic evaluation - should be extensive to rule out other causes • Treatment - many therapies suggested - few are statistically proven except for bed rest and possibly 95% O2:5% CO2 inhalation and steroid therapies. Patient is usually admitted to the hospital for treatment. By Dr S.Rabiei

24. Acoustic nerve tumor • Uncommon tumor. Usually arises in vestibular nerve and is schwannoma, or less often, neurilemmoma • Usually present with hearing loss. Progression of vestibular nerve involvement is so slow that it is not noticed by patient. • Characteristic audiometric results with abnormal acoustic reflex, poor discrimination, and/or abnormal ABR. • X-rays or CT show flaring of IAC in large tumors. Small tumors are seen with air contrast CT • Treatment - surgical excision By Dr S.Rabiei

25. Infections • Viral infection • Bacterial infection - labyrinthitis, meningitis, etc. • Otosclerosis • SNHLoften seen in otosclerosis of foot plate, but occurrence of pure sensorineural hearing loss is controversial • Treatment with fluoride may be helpful By Dr S.Rabiei

26. Occupational hearing loss By Dr S.Rabiei

27. Introduction • Noise-induced hearing loss is a sensorineural hearing deficit • begins at the higher frequencies (3000 to 6000 Hz ) • chronic exposure to excessive sound levels • is typically symmetric By Dr S.Rabiei

28. Socioacusis • When the noise exposure causing hearing loss is associated with nonoccupational activities • Noise ? By Dr S.Rabiei

29. Acoustic trauma • one-time, brief exposures followed by immediate permanent hearing loss • exceed 140 dB and are often sustained for less than 0.2 seconds • tearing of membranes + disruption of cell walls with mixing of perilymph and endolymph. By Dr S.Rabiei

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31. Occupational noise-induced hearing loss ONIHL • When the injurious noise is present in the workplace By Dr S.Rabiei

32. Gunshot (peak level)140 to 170 db • Jet takeoff 140 • Rock concert 110 to 120 • stereo headphones 110 to 120 • Motorcycle 90 • Conversation 60 • Quiet room 50 By Dr S.Rabiei

33. Epidemiology • second most common sensorineural hearing loss - after age-related hearing loss (presbycusis). • 28 million Americans with some degree • 10 million have hearing loss • "boilermakers' disease," By Dr S.Rabiei

34. Pathophysiology: • Distorted stereocilia • Absence of organ of Corti • Rupture of the Reissner membrane • no changes in the blood vessels, spiral ligament, or limbus • Outer hair cells are more susceptible to noise exposure By Dr S.Rabiei

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36. Two general theories metabolic exhaustion mechanical trauma • decreased endolymphatic oxygen tension • . Decreases in succinic dehydrogenase and glycogen The greatest area of injury appears to be to that portion of a cochlea sensitive to frequencies around 4000 (Hz). By Dr S.Rabiei

37. low-frequency losses rarely exceed 40 dB • Loss is usually greatest at 4000 Hz • The 4000-Hz notch is often preserved even in advanced stages. By Dr S.Rabiei

38. T.T.S : Temporary threshold shifts • decreased stiffness of the stereocilia of OHCs. • TTS may be due to metabolic exhaustion • TTS is sometimes referred as "auditory fatigue." • prolonged periods of time : cell death By Dr S.Rabiei

39. Clinically, NIHL begins with a TTS • a temporary neurosensory hearing loss that recovers almost completely once the noxious stimulus is removed • days or months may be required to recover TTS, at least 24 hrs. • in occupational situations, temporary threshold shifts are almost always greatest between 3000-6000 Hz and are often quite narrowly focused at 4000 Hz. By Dr S.Rabiei

40. PTS : permanent threshold shifts • fusion of adjacent stereocilia and loss of stereocilia. • loss of adjacent supporting cells • complete disruption of the organ of Corti • the primary site of injury appears to be the rootlets that connect the stereocilia to the top of the hair cell By Dr S.Rabiei

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42. History: • after many years of exposure • generally 10 years or more • More males than females are reported to have NIHL • No clear-cut differences exist between young and older individuals but? By Dr S.Rabiei

43. High-frequency noise is much more damaging than low-frequency noise • Continuous stimuli are more damaging than interrupted stimuli • Intermittent noise is defined as loudness levels that fluctuate more than 20 dBA. • NIHL begins with selective loss of hearing at around 4000 Hz (although not pathognomonic ) • Tinnitus associated with both TTS and PTS. By Dr S.Rabiei

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45. Diagnosis : • Early detection by OAE testing - microphonic sounds OHCs - TTS by OAE • PTA • high frequency SNHL • 4000 Hz notch • flat SNHL By Dr S.Rabiei

46. Not treatment Only prevention Role of physician is education & early detection and prevention!!! R/O other condition (ototoxicity , aging) By Dr S.Rabiei

47. Standard for the maximum sound intensity tolerable over certain lengths of time • Duration of 16 hours - 85 dBA • Duration of 8 hours - 90 dBA • Duration of 6 hours - 92 dBA • Duration of 4 hours - 95 dBA • Duration of 3 hours - 97 dBA • Duration of 2 hours - 100 dBA • Duration of 1.5 hours - 102 dBA • Duration of 1.0 hour - 105 dBA • Duration of 30 minutes - 110 dBA • Duration of 15 minutes - 115 dBA Occupational Health and Safety Administration (OSHA) By Dr S.Rabiei

48. Since each 3 dB of loudness increase represents a doubling of sound energy, the amount of damage expected from 8 hours of exposure to 100 dB should be about the same as the amount of damage sustained from 4 hours of exposure to 105 dB. By Dr S.Rabiei

49. Tage bostan By Dr S.Rabiei

50. Protectors • Earplugs: 15-30 db in 2 – 5 kHz if sealed correctly work in mid to high frequency • Earmuffs : 30- 40 db un 500hz – 1 kHz By Dr S.Rabiei