Hearing Evaluation.

งานนำเสนอเรื่อง: "Hearing Evaluation."— ใบสำเนางานนำเสนอ:

1 Hearing Evaluation

2 วัตถุประสงค์ เรียนรู้กระบวนการเกิดการได้ยิน
รู้จักการประเมินการได้ยินของผู้ป่วย สามารถตรวจหาความผิดปกติของการได้ยินด้วยวิธีใช้ส้อมเสียง และส่งต่อผู้ป่วยอย่างถูกวิธี รู้จักการตรวจการได้ยินและการทดสอบที่เกี่ยวข้องต่างๆ

3 Contents Anatomy of the ear Hearing mechanism Tuning fork test
Audiometry Tympanometry ABR,OAE

4 ANATOMY OF THE EAR

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14 Mechanism of hearing

15 The pinna important to localized sound source in vertical plan
Aids in localization more efficient at high frequency

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17 Ear canal provide 10-15dB in 2500-6000Hz
Best at 2500 Hz

18 EAC Open in oval 9-10mm.high, 8-9mm. wide, 25mm.long
Average sound increase dB

19 Human middle ear best transmission 500-2000 Hz

20 ME TM. Ossicle(M,I,S) Tensor tympani , Stapedius
Stapedius response 85 dB

21 ME The area effect of the TM(55mm2) vs stapes footplate(3.2mm2), result in 17:1 increase sound energy Lever action of ossicular chain : handle of malleus 1.3 times longer than incus long process Total transform ratio is about 22:1(=25 dB)

22 AREA EFFECT & LEVER ACTION

23 Basic Hearing Test Tuning Fork Test Audiometry

24 HEARING TEST???

25 Tuning Fork Weber Test Rinne Test Bing Test Gelle Test Schwabach test

26 Weber Test Compare BC between Rt & Lt ear
Sound is heard equally in both ears = no lateralization CHL : sound in poorer ear is louder SNHL : sound in better ear is louder

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28 Rinne Test Compare AC & BC AC>BC = normal conducting system
= Rinne positive BC>AC = CHL = Rinne negative Detect conduction defect เมื่อ ABG > 15 dB

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30 Audiometry Pure tone audiometry Speech audiometry

31 Pure tone audiometry

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35 Conductive hearing loss: criteria
The BC better than the AC The air-bone gap at least 15 dB The BC must be normal The discrimination must be good

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38 Sensorineural hearing loss : criteria
The AC and BC threshold are reduced No air-bone gap

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43 Figure 152-1. Audiogram showing a range of hearing loss.

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47 Thai noise legislation
Maximal noice allowance in workplace is 85 dBA for 8 hours work Cars generated noise limit to 85 dBA Residential area noise generated should not be > 60 dBA

48 คนพิการตามกฎหมาย Child < 7 years: hearing in speech frequency from the better ear > 40 dB > 7 years : > 55 dB

49 Speech audiometry SRT(speech reception threshold)
SD Score (speech discrimination)

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51 SRT (speech reception threshold)
SRT is the lowest level in dB at which a patient can repeat spondee word in 50% (spondee คือคำ 2พยางค์ที่เสียงเทียบเท่ากัน เช่น eardrum) SRT should be within 10 dB of PTA

52 SDS(speech discrimination score)
Percentage of phonetically balanced (PB)words(monosyllable) that patient repeats correctly Test contained 25 PB words at SRT +35 dB ถ้าต่ำมากคิดถึงretrocochlear lesion

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54 Tympanometry Basic Principle Type Application

55 tympanometry Objective test that measure the mobility of TM (reflect of ME pressure) Five types: A, B, C, As, Ad

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57 Type A; normal ME pressure
Type B; flat fluid in ME , TM perforate Type C; negative pressureretract TM / ET dysfunction Type As;restric mobilityotosclerosis ,TM scar ,fixation of malleus Type Ad;hyper complianceflaccid TM ,ossicular disarticulation

58 Other Battery Test ABR (auditory brainstem response)
EcoG (electrocochleography) OAE (Otoacoustic emissions)

59 ABR

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63 Figure 152-7C. A, Audiogram, B, transient evoked otoacoustic emissions and C, auditory brain stem responses from a patient with a 7-mm intracanalicular left-sided acoustic neuroma.

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65 electrocochleography
EcoG measures the potential arising within cochlea and auditory nerve

66 EcoG Figure Electrocochleography responses recorded from the human ear canal using condensation (C) and rarefaction (R) click stimuli. The major component of the whole-nerve action potential (N1), the summating potential (SP), and the cochlear microphonic (CM) are marked. The CM and the SP can be selectively enhanced by adding (R + C) or subtracting (R − C) the recordings made using rarefaction and condensation click. Ear canal negative deflections potentials are plotted as downward deflections. (From ASHA Workgroup on Auditory Evoked Potentials. The short latency auditory evoked potentials, Rockville, Maryland, 1987, ASHA, p 9, Figure 4 [based on work from Coates, 1981]. Copyright by the American Speech-Language-Hearing Association. Reprinted with permission.)

67 Normal Figure Electrocochleogram obtained with a tympanic membrane surface electrode from a normal ear: the summating potential/action potential ratio is normal at 0.13.

68 Meniere’s Figure Electrocochleogram obtained from the ear of a patient with M้ni่re’s disease: the summating potential/action potential ratio is elevated (0.81).

69 Otoacoustic emissions(OAEs)
Confirm SNHL > 40dB Absent in cochlea lesion Present in neural lesion Objective test,noninvasive ,efficient Limited by conductive hearing loss

70 OAE Figure 152-6A. A, Transient evoked otoacoustic emissions and B, distortion-product otoacoustic emissions from the same normal-hearing ear.

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72 OAE Figure 152-7B. A, Audiogram, B, transient evoked otoacoustic emissions and C, auditory brain stem responses from a patient with a 7-mm intracanalicular left-sided acoustic neuroma.

73 Historical risk factors for hearing loss in newborn
Family history Hyperbilirubinemia requiring exchange Congenital infection (TORCHS) Craniofacial anormalies Birth weight less than 1500gm

74 Historical risk factors for hearing loss
Bacterial meningitis Apgar scores ≤ 3 at 5 minutes Ototoxic medications > 5 days Prolonged mechanical ventilator (>10days) Stigmata or others findings associated with a syndrome known to include HL

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76 การตรวจการได้ยินในเด็ก
Since birth : objective tests ABR, OAE(otoacoustic emission) 6-30 months: behavioral tests 6-18 months Distraction test 6-30 months Visual Reinforcement Audiometry (VRA) > 30 months : Pure Tone Audiometry

77 Distraction test Visual Reinforcement Audiometry (VRA)
Behavioral tests Distraction test Visual Reinforcement Audiometry (VRA)

78 Distraction test 6-18 months Child turns to localize the sound source

79 Visual Reinforcement Audiometry (VRA)
Sound Head turn Visual stimuli

80 Visual reinforcement audiometry
6-30 months

81 Thank you