assesment of hearing
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ASSESSMENT OF HEARING MODERATOR:-DR N. JANARDHAN
BY:-RAMA RAJU
CONDUCTIVE HEARING LOSS:PATHOLOGY IN :
1. EXTERNAL EAR(OBST)
2.TYMPANIC MEMBRANE ( PERF )
3.MIDDLE EAR (EFFUSION)
4.OSSICLES (FIXATION)
5.E.T (OBST)
SNHL
1. COCHLEAR
2. VIII NERVE
3. CENTRAL CONNECTIONS.
2 AND 3 CONSTITUTE TO RETRO COCHLEAR REGION.
MIXED
IN OTOSCLEROSIS
CSOM
1. INCREASING A-B GAP :CONDUCTIVE DEAFNESS.
2. DECREASING BONE CONDUCTION INDICATES SNHL.
TUNING FORK TEST :
RINNE TESTPOSITIVE :(AC>BC)1. NORMAL
2. SNHL
NEGATIVE : (BC>AC)3. CONDUCTIVE
DEAFNESS
4. SEVERE SNHL (FALSE -VE)
WEBERS TESTCENTRALISED : NORMAL
LATERALISED :
TO AFFECTED EAR : CONDUCTIVE DEAFNESS
TO NORMAL EAR :SENSORINEURAL DEAFNESS
ABSOLUTE BONE CONDUCTION TEST EAC OF BOTH SUBJECT AND EXAMINER OCLUDED.
PATIENT AND EXAMINER HEARS THE TUNING FORK FOR THE SAME TIME :-CONDUCTIVE DEAFNESS
1. SUBJECT HEARS THE TUNING FORK FOR SHORTER DURATION:-
SNHL
SCHWABACH'S TEST
PATIENT HEARS THE FORK FOR SHORTER DURATION:-SNHL
DURATION IS LENGTHENED IN :-CONDUCTIVE DEAFNESS
BING TEST: BONE CONDUCTION TEST WHICH EXAMINES THE EFFECT OF OCCLUSION OF CANAL ON THE HEARING
BONE CONDUCTION LOUDER WHEN EAR CANAL IS OCCLUDED:-
1. NORMAL
2. SNHL
NO CHANGE :-CONDUCTIVE DEAFNESS
GELLE'S TEST:TO TEST THE FUNCTIONING OF OSSICULAR CHAIN
INCREASE IN PRESSURE OF MEATUS
1. DEECREASE IN LOUDNESS FROM BONE CONDUCTED STIMULUS:-NORMAL,SNHL
2. NO ALTERATION OF BONE CONDUCTION-FIXATION OF STAPES IN OTOSCLEROSIS
PURE TONE AUDIOMETRY
PURE TONE : SINGLE FREQUENCY SOUND WAVE.
AIMS OF PTA : TO KNOW IF SUBJECT HAVE DEFINITIVE
AUDITORY DISORDER.
TYPE OF HEARING LOSS - CONDUCTIVE/MIXED/SNHL.
SNHL: COEHLEAR OR RETROCOCHLEAR
DEGREE OF HEARING DYSFUNCTION
INTERPRETATION OF AUDIOGRAM
ONLY QUANTITATIVE TEST NATURE OF PATHOLOGY AND SITE OF LESION NOT KNOWN .
AIR CONDUCTION THRESHOLD DEAFNESS GRADED INTO:
0-25 : NORMAL HEARING THRESHOLD
26-40 : MILD DEAFNESS
41-55:MODERATE DEAFNESS
56-70:SEVERE DEAFNESS
71-90:VERY SEVERE DEAFNESS
ABOVE 90:PROFOUND DEAFNESS
CONDUCTIVE DEAFNESS:
BONE CONDUCTION - NORMAL (15-20 db HL)A-B GAP =>20 db
•SENSORINEURAL DEAFNESS :BONE CONDUCTION=>20 db HL A-B GAP:<= 15 db
MIXED DEAFNESS:
BONE CONDUCTION=>20 db HL.A-B GAP: >= 15 db
CONDUCTIVE LESIONS:OTOSCLEROSIS:1.LEFT SLOPING AUDIOGRAM2.CARHART'S NOTCH IN BONE CONDUCTION HEARING LEVEL AT 2000HZ
SECRETORY OTITS MEDIA:RIGHT SLOPING AUDIOGRAM
OSSICULAR DISCONTINUITY:>60 db A-b GAP
SENSORINEURAL HEARING LOSS:FLAT AUDIOGRAM SUGGESTS ATROPY OF STRIA VASCULARIS(STRIAL PRESBYCUSIS)
SELECTIVE HIGH FREQUENCY LOSS WITH NORMAL HEARING IN MIDDLE AND LOW FREQUENCY SUGGESTS LESION OF CORTI DUE TO1.SOUND TRAUMA2.OTOTOXIC DRUGS
ASCENDING CURVE (SLOPE TO LEFT) SUGGESTS EARLY ENDOLYMPHATIC HYDROPS
TROUGH SHAPED AUDIOGRAM SUGGESTS CONGENITAL SENSORINEURAL LESION
FALLACIES OF PTA :
1. IMPROPER TECHNIQUE : OVER MASKING/UNDERMASKING
FAULTY PLACEMENT OF HEADPHONES OR BONE CONDUCTION VIBRATOR
2.IMPROPER TEST INSTRUMENT : IMPROPER CALIBRATION
LAX HEADBAND
3.IMPROPER EXAMINER :
LIMITATIONS OF PTA :
1. PTA DOES NOT EVALUATE THE PROPERTIES OF SUPRA THRESHOLD HEARING i.e., FREQUENCY DISCRIMINATION AND TEMPORAL RESOLUTION.
2. IT DOES NOT IDENTIFY THE NATURE OF PATHOLOGY.
3. BONE CONDUCTION TEST DOES NOT ASSESS THE TRUE SENSORINEURAL RESERVE AS T.M AND OSSICLES ALSO CONTRIBUTE FOR BONE CONDUCTION.
IMPEDANCE AUDIOMETRY
1. USES:OBJECTIVE DIFFERENTIATION BETWEEN CONDUCTIVE AND S.N HEARING LOSS
2. D.D IN CASES OF CONDUCTIVE DEAFNESS
3. MEASUREMENT OF MIDDLE EAR PRESSURE AND E.T FUNCTION
4. D.D OF SNHL i.e COCHLEAR OR RETRO-COCHLEAR
5. IDENTIFICATION OF SITE OF FACIAL NERVE LESION AND CERTAIN BRAIN STEM PATHOLOGIES
TESTS OF IMPEDANCE AUDIOMETRY
1. TYMPANOMETRY
2. EUSTACHIAN TUBE FUNCTION TEST
3. ACOUSTIC REFLEX TEST
TYMPANOMETRY
TYMPANOMETRY IS DEFINED AS THE MEASUREMENT OF CHANGE OF IMPEDANCE OF THE MIDDLE EAR AT THE PLANE OF T.M AS A RESULT OF CHANGE IN AIR PRESSURE OF E.A.C
PROCEDURE
1. PROBE WITH 3 CHANNELS FIT IN TO E.A.C,TO DELIVER A TONE OF 220 HZ
2. TO PICK UP A REFLECTED SOUND THROUGH A MICRO PHONE
3. TO BRING PRESSURE CHANGES IN E.A.C
PRESSURE CHANGED FROM +200 TO -600 WATER PRESSURE AND THE COMPLIANCE VALUES ARE RECORDED EVERY 50 mm change
PRESSURE AT WHICH COMPLIANCE IS MAXIMUM IS MIDDLE EAR PRESSURE
STATIC COMPLIANCECx=C2-C1range=.35to1.40
COMPLIANCE OF AUDITORY CONDUCTIVE SYSTEM AS MEASURED AT T.M
COMPLIANCE
1.OSSICULAR CHAIN DISCONTINUITY2.SCARRED T.M3.LARGE T.M4.POST STAPEDECTOMY EAR
COMPLIANCE
1.OTOSCLEROSIS
2.SECRETORY O.M
3.OSSICULAR FIXATION
4.TYMPANOSCLEROSIS
NORMAL COMPLIANCE
1.SOME CASES OF OTOSCLEROSIS
2.EUSTACHIAN TUBE OBSTRUCTION EITH OUT SECRETORY CHANGES IN MIDDLE EAR
MIDDLE EAR PRESSURENORMAL MIDDLE EAR PRESSURE=+50 TO -50 OF WATER PRESSURE
NEGATIVE PRESSURE CONDT:
1. BLOCKED E.T
2. SECRETORY OTITIS MEDIA
POSITIVE MIDDLE EAR PRESSURE:
3. EARLY ACUTE OTITIS MEDIA
ABSENCE OF PRESSURE:
4. ADHESIVE OTITIS MEDIA
5. PERFORATION OF T.M
6. PATENT GROMMET IN T.M
7. CERUMEN BLOCKING EXTERNAL EAR
TYPES AND SHAPES OF TYMPANOGRAMS
TYPE A : SHARP MAXIMUM AT PEAK 0 mm OF H2O HgCONDT: 1.NORMAL EAR
2.OTOSCLEROSIS (SOME CASES)
TYPE As: NORMAL MIDDLE EAR PRESSURE WITH LOW COMPLIANCE
CONDT: 1.OTOSCLEROSIS
2.THICKENED T.M
TYPE Ad: NORMAL MIDDLE EAR PRESSURE WITH HIGH COMPLIANCE
CONDT: 1.OSSICULAR DISCONTINUITY
2.SCARRING OF T.M
TYPE B : FLAT TYMPANOGRAM ( COMPLIANCE UNCHANGED OVER PRESSURE VARIATION)
CONDT : 1.OTITIS MEDIA WITH EFFUSION
2. ADHESIVE OTITIS MEDIA
3. PERFORATION OF T.M
TYPE C: NEGATIVE MIDDLE EAR PRESSURE WITH NORMAL COMPLIANCE
CONDT:1.UNCOMPLICATED E.T OBSTRUCTION
TYPE A:NORMAL TYMPANOGRAM WITH MAX COMPLIANCE AT AMBIENT ATMOSSPHERIC PRESSURE
TYPE Ad:NORMAL MIDDLE EAR PRESSURE ,HIGH COMPLIANCE TYMPANOGRAM1.OSSICULAR DISCONTINUITY2.SCARRED T.M
TYPE As:LOW COMPLIANCE ,NORMAL MIDDLE EAR PRESSURE1.STAPEDIAL OTOSCLEROSIS2.OSSICULAR FIXATION
TYPE B:FLAT TYMPANOGRAM WITHOUT MEASURABLE COMPLIANCE1.GROSS S.O.M2.GROSS ADHESIVE CHANGES3.PERFORATION
• NEGATIVE MIDDLE EAR PRESSURE,LOW COMPLIANCE TYMPANOGRAM
-VE PRESSURE DUE TO E.T BLOCKADECOMPLIANCE IS DUE TO SOME AIR PRESENT
TYPE C : NEGATIVE MIDDLE EAR PRESSURE,NORMAL COMPLIANCE WITH SINGLE PEAK
SUGGESTS BLOCKED E.T WITHOUT COLLECTION OF FLUID
•NORMAL MIDDLE EAR PRESSURE,LOW COMPLIANCE WITH SYSTEMIC WAVES IN THE TYMPANOGRAM CORRESPONDING WITH PULSE BEAT SUGGESTS GLOMUS JUGULARE IN MIDDLE EAR
EUSTACHIAN TUBE FUNCTION TESTS:
1. FUNCTIONS OF E.T:MAINTAINANCE OF EQUALITY OF AIR PRESSURE b/w MIDDLE EAR AND AMBIENT ATMOSPHERIC PRESSURE
2. DRINAGE OF MUCOUS FROM MIDDLE EAR
I.A ASSES TUBAL FUNCTION OF MIDDLE EAR AND NOT JUST ANATOMICAL PATENCY
2TESTS
1.WILLIAMS TEST
2.TOYNBEE'S TEST
WILLIAM'S TEST
I.A MEASURES MIDDLE EAR PRESSURE IN 3 COND IN WILLIAMS TEST1.RESTING PRESSURE
2. SWALLOWING
3.VALSALVA MANOVEUR
NORMAL=NORMAL RESTING ATMOSPHERIC PRESSURE TURNS NEGATIVE ON SWALLOWING AND POSITIVE ON VALSALVA MANOVEUR
PARTIALLY IMPAIRED=TURNS NEGATIVE ON SWALLOWING BUT RETAINS NORMAL ON VALSALVA AND VICE-VERSA
COMPLETELY IMPAIRED=NO CHANGE ON SWALLOWING AND VALSALVA
NORMAL : NORMAL ATMOSPHERIC PRESSURE TURNS NEGATIVE ON SWALLOWING AND POSITIVE ON VALSALVA MANOVEUR
PARTIALLY IMPAIRED :TURNS NEGATIVE ON SWALLOWING AND REMAINS NORMAL ON VALSALVA MANOVEUR AND VICE - VERSA
COMPLETELY IMPAIRED:NO CHANGE OF PRESSURE ON SWALLOWING AND VALSALVA
TOYNBEE'S TEST: (PERFORATED EARDRUM )
I.A IS PROGRAMMED TO ARTIFICIALLY INCREASE OR DECREASE THE AIR PRESSURE IN THE MIDDLE EAR AND THEN RECORD THE CHANGE IN THE PRESSURE OF MIDDLE EAR EACH TIME THE PATIENT SWALLOWS.
TEST IS CARRIED FOR 40 SEC.
PROCEDURE: PRESSURE IS INCREASED TO +250 OR -250 mm
WATER PRESSURE.
PATIENT IS ASKED TO SWALLOW REGULARLY.
LOOK IF PRESSURE IS BEING NEUTRALISED WITH EACH SWALLOW.
STEP LADDER TYPE OF GRAPH.
PARTIALLY IMPAIRED:IF RESIDUAL PRESSURE PERSISTS EVEN AFTER 5 SWALLOWS
GROSSLY IMPAIRED:IF THE PRESSURE CANNOT BE NEUTRALISED EVEN AFTER REPEATED SWALLOWS
ACOUSTIC REFLEX TEST:
1. HELPS INELIMINATION OF MIDDLE EAR PATHOLOGY
2. DIFFERENTIATION OF COCHLEAR FROM RETROCOCHLEAR LESION
3. DETECTION OF SOME BRAIN STEM PATHOLOGY
4. OBJECTIVE ESTIMATION OF AVERAGE HEARING THRESHOLD LEVEL
5. DETECTION OF NON ORGANIC HEARING LOSS
6. IDENTIFYING THE LEVEL OF LESION IN FACIAL NERVE PARALYSIS
INTERPRETATION OF ACOUSTIC REFLEX :
AR(+) :-
1. STRONGLY INDICATE ABSENCE OF PATHOLOGY IN THE REFLEX PATHWAY.
2. IN COCHLEAR LESIONS DUE TO LOUDNESS RECRUITMENT.
AR (-) :-1. EVIDENCE OF LESION IN REFLEX PATHWAY.
2. SOMETIMES EVEN IN NORMAL PEOPLE WHEN TEST IS DONE AT FREQUENCY OF 4000 Hz.
UNILATERAL MODERATE TO SEVERE CONDUCTIVE DEAFNESS
STIMULUS IN DEAF EAR : I/L AR (-)
C/L AR (-)
AS STIMULUS FROM THE DEAF EAR DOES NOT REACH THE REFLEX ARC .
STIMULUS IN NORMAL EAR : I/L AR (+)
C/L AR (-)
CONTRALATERAL AR (-) BECAUSE OF MIDDLE EAR PATHOLOGY.
BILATERAL CONDUCTIVE DEAFNESS
AR (-) IN BOTH EARS DUE TO THE PRESENCE OF MIDDLE EAR LESION WHICH CAUSES MECHANICAL OBSTRUCTION TO THE REFLEX.
UNILATERAL SEVERE SENSORINEURAL DEAFNESS
STIMULUS IN DEAF EAR :- I/L AR (-)
C/L AR (-)
STIMULUS DOES NOT REACH THE REFLEX PATHWAY
STIMULUS IN NORMAL EAR :-I/L AR (+)
C/L AR(+)
AR(+) IN DEAF EAR AS THE MIDDLE EAR IS INTACT
IN BILATERAL SNHL:
SEVERE AND NEURAL:-AR(-) IN I/L AND C/L EARS
MODERATE AND COCHLEAR:AR(+) IN I/L AND C/L EARS
DUE TO LOUDNESS RECRUITMENT
CENTRAL LESIONS:
AR(+):-BILATERALLY ON IPSILATERAL STIMULATION
AR(-):-ABSENT BILATERALLY ON C/L STIMULATION
LESIONS INVOLVE THE SITE OF CROSSINGS BETWEEN I/L AND C/L SIDES
RECRUITMENT:
ABNORMAL STEEP GROWTH OF LOUDNESS WITH INCREASING INTENSITY
ASSOCIATED WITH SENSORINEURAL DEAFNESS DUE TO COCHLEAR PATHOLOGY
EXACT CAUSE OF MECHANISM OF RECRUITMENT NOT UNDERSTOOD
ABSENCE OF RECRUIMENT IS PATHOGNOMIC OF RETROCOCHLEAR LESION
ABSENCE OF RECRUITMENT DOES NOT RULE OUT COCHLEAR PATHOLOGY
TESTS
1. ALTERNATE BINAURAL LOUDNESS BALANCE TEST :ITS A DIRECT TEST
2.SHORT INCREMENT SENSTIVITY INDEX :
ITS AN INDIRECT TEST
ABLB
PROCEDURE:
STEP 1: HEARING THRESHOLD BY AIR CONDUCTION FOR THE TESTING FREQUENCY IA ASCERTAINED
STEP2: ATTENUATOR DIAL FOR WORSE EAR IS 20 dB SL,FOR THE BETTER EAR IS 0 dB
STEP3: TONES ALTERNATE BETWEEN TWO EARS AND PATIENT IS ASKED TO INDICATE IN WHICH EAR SOUND APPEARS LOUDER
a)LOUDER IN WORSE EAR-FOLLOW STEP 4
b)LOUDER IN NORMAL EAR -FOLLOW STEP5
STEP 4: TONE IN BETTER EAR IS RAISED BY 5 dB
STEP 5: TONE IN THE BETTER EAR DECREASED BY 5dB
INTERPRETATION OF ABLB RESULTS:
COMPLETE RECRUITMENT:THE DIFFERENCE IN THE HEARING LEVEL B/W WORSE AND BETTER EAR DIMINISHES RAPIDLY WITH INCREASE IN THE INTENSITY OF SOUND AND AT A POINT DIFFERENCE BECOME ZERO
ABSENCE OF RECRUITMENT:(NEURAL PATHOLOGY WITH NORMAL COCHLEAR FUNCTION)THE DIFFERENCE IN THE HEARING LEVEL REMAINS CONSTANT ,NO MATTER WHATEVER THE INTENSITYO OF SOUND IS
PARTIAL RECRUITMENT:THE DIFFERNCE IN THE HEARING LEVEL BETWEEN TWO EARS FOR EQUAL LOUDNESS SENSATION GRADUALLY DIMINISHES WITH INCREASING INTENSITY ,BUT DIFFERENCE NEVER BECOME ZERO
SISI TEST
PROCEDURE :
1. DETERMINES THE CAPACITY OF PT TO DETECT A BRIEF 1 db INCREMENT 20 db SUPRATHRESHOLD TONE IN VARIOUS FREQUENCY.
2. TWENTY SUCH 1 db INCREMENTS ARE PRESENTED TO EAR AND PATIENT ASKED TO COUNT HOW MANY OF THE 1 db INCREMENTS HE COULD CORRECTLY IDENTIFY.
3. THIS WHEN MULTIPLIED WITH 5 GIVES THE % OF SISI SCORE.
4. INITIALLY HIGHER INCREMENTS (6 db,5 db,3 db etc) given to familiarise the patient with of identifying the smaller lessions.
INTERPRETATIONS OF SISI SCORE
SISI SCORE IS USED TO DIFFERENTIATE BETWEEN COCHLEAR AND RETROCOCHLEAR LESSIONS.
SESI % :
70-100% - (>1000 Hz) 80-100% -(2000-4000 Hz) 0-20% - RETROCOCHLEAR PATHOLOGY NORMAL HEARING CONDUCTIVE DEAFNESS
SISI : NOT ENTIRELY FOOLPROOF HAS ITS OWN LIMITATIONS
LIMITATIONS OF SISI
REQUIRES PATIENT CO-OPERATION.PT WITH SEVERE DEAFNESS (>85 db) CANNOT BE TESTED AS MOST CLINICAL AUDIOMETER USUALLY HAVE MAX SOUND OUTPUT OF UPTO 100 db.
MILD (30 db) SNHL - DOES NOT SHOW HIGH SCOREEVEN IF DEAFNESS IS DUE TO COCHLEAR LESSIONS.
TONE DECAY TEST
IT MEASURES THE RAPIDITY OF DETERIORATION IN THE THRESHOLD OF HEARING WHEN A CONTINUOUS TONE IS PRESENTED TO EAR.
1. OF ALL TEST,TONE DECAY TEST IS COMMONLY USED TO DETECT THE SITE OF PATHOLOGY IN THE SENSORINEURAL PATHWAY.
2. TEST IS MANDATORY TO BE CARRIED OUT IN EVERY CASE OF SENSORINEURAL DEAFNESS.
3. EXACT PATHOPHYSIOLOGY OF TONE DECAY IS NOT KNOWN.
PROCEDURE
TYPES :1. CARHART'S METHOD
2. GREEN'S MODIFIED METHOD
3. OLSEN AND NOFFSINGER TEST
4. ROSENBERG'S METHOD
5. SUPRATHRESHOLD ADAPTION TEST (STAT)
CARHART'S METHOD
MOST POPULAR METHOD
STEP 1 :- PURE TONE STIMULUS IS PRESENTED 10 db BELOW THRESHOLD AND RAISED IN 5 db STEPS TILL THE PATIENT RESPONDS.
STEP 2 :- AFTER THE PATIENT RESPONDS A STOP WATCH IS STARTED AND TONE IS CONSTANTLY MAINTAINED.
STEP 3 :- AS SOON AS HE FAILS TO HEAR THE TONE TIME ON THE STOP-WATCH IS NOTED.IF THE TONE IS HEARD FOR ONE FULL MIN. THEN TEST IS TERMINATED,IF PATIENT STOPS HEARING < 1 min,THEN TIME IS RECORDED AND STEP IV IS STARTED.
STEP 4 :- TONE RAISED BY 5 db WITHOUT ANY GAP RAISING OF THE INTENSITY OF THE TONS BY 5 db STEPS IS CONTINUED TILL 30db ABOVE THRESHOLD.
INTERPRETATION OF TONE DECAY RESULTS
1. 0-5 db = normal
2. 10-15 = mild
3. 20-25 = moderate
4. 30 and above = severe
SEVERE DECAY IS CONSIDERED TO BE SUGGESTIVE OF RETROCOCHLEAR LESSION (>30 db )
IT IS NOT FOOLPROOF EVIDENCE OF RETROCOCHLEAR PATHOLOGY.
AFTER TONE DECAY TEST, IF SEVERE THEN THE PATIENT SHOULD BE SUBJECTED TO DETAILED NEURO-OTOLOGICAL EXAMINATION.
THE END