Non organic hearing loss

Question 1

What is the definition of non-organic hearing loss?

Answer 1

Hearing loss that appears greater (on audiological testing) that can be explained on the basis of pathology in the auditory system

Question 2

What are some examples of factors that may motivate nonorganic hearing loss?

Answer 2

-Lack of understanding of the test procedure
-Poor motivation
-Physical or emotional incapability of appropriate responses
-Wish to conceal a handicap
-Deliberate feigning or exaggeration of hearing loss for personal gain or exemption
-Some degree of psychological disturbance

Question 3

What kind of disorder may appear as a non organic hearing loss but is actually something different?

Answer 3

Neurological problems such as auditory processing disorder which may cause patients to appear with “normal hearing” but problems communicating due to a problem in the CNS

Question 4

What are indications of non organic hearing loss prior to any audiological testing?

Answer 4

1. Source of referral- e.g. if they have been referred by an attorney or if they are a veteran
2. Case history- over-reliance on lipreading, ask for constant repetition of words, exaggerated and contradictory statements about hearing loss, may use exaggerated actions and manoeuvres

Question 5

What are indications of a non organic hearing loss during the audiological testing?

Answer 5

-Frequent inconsistencies in the test responses
-False negatives i.e. patient does not respond at levels of or above true thresholds
-False positive i.e. highly responsive patient who responds even when the tone was not presented
-Extremely slow or deliberate responses
-Flat audiogram showing equal amounts of hearing loss across frequencies
-Ignorance of the manner in which loudness grows with respect to intensity

Question 6

What is an indication of non organic hearing loss on the shadow curve?

Answer 6

-Patients feigning a hearing loss may claim it is only occuring in one ear
-This allows them to have a normally hearing ear which prevents them being “tripped up” in conversation
-The patient may therefore give responses which indicate very good hearing in one ear and a big hearing loss in the other ear
-If there is no contralateral response, especially by bone conduction, this indicates a unilateral nonorganic hearing loss

Question 7

How is an SRT and pure-tone average disagreement indicative of a non organic hearing loss?

Answer 7

-SRT is usually favourably comparable with the average of the lowest two thresholds obtained at 500, 1000 and 2000 Hz
-Lack of agreement between SRT and PTA in the absence of explanations such as slope of audiogram or poor word recognition suggests nonorganic hearing loss
-SRT is lower (better) than PTA in confirmed cases of nonorganic hearing loss by more than 10 dB

Question 8

What quantitative tests can be used if nonorganic hearing loss is suspected?

Answer 8

1. Auditory-evoked potentials- early evoked potentials proven to be more reliable than the middle latency responses in detecting nonorganic hearing loss
2. Otoacoustic emissions- especially TEOAEs may reveal if hearing is normal or near normal
3. Puretone Delayed Auditory Feedback (DAF)- patient asked to tap out a continuous pattern, then a tone pulse is added and if the tone is audible the patient will vary the tapping behaviours

Question 9

How is the acoustic immittance measurement test used to test for nonorganic hearing loss?

Answer 9

-The acoustic reflex threshold is the immittance measurement
-If it is elicited at a low sensation level (60 dB or less above the voluntary threshold) it suggests the presence of a cochlear lesion
-However if the difference between the acoustic reflex threshold and the voluntary pure tone is very low (e.g. 5 dB) it is an indication of a possible non organic hearing loss

Question 10

What is the Stenger test?

Answer 10

-When two tones of the same frequency are introduced simultaneously into both ears, only the louder tone will be perceived
-One tone presented is presented at 10 dB above the threshold in the better ear and another tone is presented at 10 dB below the threshold in the poorer ear
-Patients with organic hearing loss will only respond to the signal in the good ear

Question 11

How is the ascending-descending (A-D) method used when nonorganic hearing loss is suspected?

Answer 11

-Ascending and descending PTA approach
-Greater than 10 dB difference between measurements suggests a nonorganic problem
-This difference can be as big as 30 dB for patients with nonorganic hearing loss with the ascending method

Question 12

How is the swinging story test and the varying intensity story test used to test for nonorganic hearing loss?

Answer 12

-Story is read to the patient with portions directed above the threshold of the normal ear through one channel and the other portions below the threshold of the “poorer ear”
-The story is presented rapidly and switches between the two channels
-Patient is required to repeat the story
-Repetition of the information directed to the good ear or both ears is expected
-Any information recalled from the poorer ear must have been heard below the patient’s admitted threshold for speech

Question 13

How is the low-level speech recognition test used to test for nonorganic hearing loss?

Answer 13

-Normally low word recognition scores are expected at low sensation levels
-Unusually high word recognition scores can be obtained on patients with nonorganic hearing loss at levels slightly above their admitted thresholds

Question 14

How is the pulse-count test used to test for nonorganic hearing loss?

Answer 14

-Puretone pulses are presented in rapid succession
-Patient is asked to count and recall number of pulses
-Intensity of pulses varied above and below the admitted thresholds of the tone in one ear or above the threshold in one ear and below the threshold of the other ear

Question 15

How is the yes or no test used to test for nonorganic hearing loss?

Answer 15

-Intended for children
-The patient is asked to say “yes” when the tone is heard and “no” when the tone is not heard
-The tone is presented at the lowest limit of the audiometer and increased in intensity in 5 dB steps
-Some patients will say “no” at exactly the same time as the introduction of the tone which shows that it was heard

Question 16

What is the Stenger principle?

Answer 16

The Stenger principle states that when tones are presented to both ears at different levels the listener is only aware of the louder tone

Question 17

Interpret this result from the Stenger test

Answer 17

-Initially the patient demonstrates exaggerated threshold at 60 dB
-Following the Stenger test the true threshold was observed at 0 dB

Question 18

What is a negative Stenger result?

Answer 18

The hearing loss is genuine and the patient responds when they hear the sound in the good ear

Question 19

What is a positive Stenger result?

Answer 19

The hearing loss is nonorganic and the patient deliberately does not respond to the tone

Question 20

How is the threshold estimated from the Stenger test?

Answer 20

-Intensity of the tone in the “poor” ear is gradually reduced until negative result is obtained (patient responds)
-Alternatively, start with 10 dB HL in good ear and 0 dB HL in poor ear
-Increase level in poor ear until positive result is obtained (no response)
-Level is known as the “minimum contralateral interference level”

Question 21

In what order should audiological testing be carried out in patients with suspected nonorganic hearing loss?

Answer 21

1. Immittance measures
2. OAE
3. SRT, including modified Stenger test in unilateral cases
4. Air conduction thresholds including Stenger test if indicated
5. Word recognition tests at low sensation levels
6. Bone conduction thresholds
7. ABR or ASSR