Category: Hearing tests

Ear Pathologies and Audiograms Part 2 – On the Soap Box

What a strange title to give to part 2 of this series! I have used this title as they are the audiograms that I talk about often, that people either miss or mistake for something else. In all cases except for some of the malingers it led to unnecessary emotional stress for the client’s involved.

Collapsed Ear Canals

Tracy who started TJ Audiology Training and no doubt many others, say that I harp on about this incessantly, and I am happy to admit I do! I think it is a real issue that we miss far too often. One research study on over 300 individuals aged between 3-97 years found that ear canal collapse was observed in 11.4% of their subjects. Prevalence ranged from 6.3% to 36.6%. With the higher percentage score being for the over 75’s. More males than females they found had the problem.

So why is this such an issue for audiograms? Canal collapse will mimic a conductive or a mixed loss. This can then lead to unnecessary ENT appointments and investigations, when all along it was a collapsed canal. This makes us as audiologists look bad if we haven’t seen it. It’s is in some cases an unnecessary referral/cost for MRI’s and ENT time. Even more importantly the personal stress to the client, who is now being investigated for a potential ear pathology cannot be underestimated.

Let’s, talk about how to check for it. Firstly, when we do otoscopy, and you are looking behind the pinna, look also at the opening to the ear canal. Is it narrow? If it is press on the middle part of the pinna. If the canal narrows, you potentially have a collapsed canal.

Client history may also be a dead giveaway! Clients, with collapsed canal will often complain that ear buds don’t stay in or are uncomfortable or they have to use the smallest ear bud. Some will even notice if they press the phone to their ear, they hear worse.

What happens during an audiogram with a collapsed ear canal?

  • The pressure from the earphone can partially or fully close the ear canal 
  • This can cause increased hearing thresholds, especially at high frequencies 
  • The results can mimic other conditions, like noise-induced hearing loss 
  • Client hears you better than their audiogram would suggest.
  • If the client already has hearing aids, they will often complain the hearing aids are too loud and/or occluding, and come back for numerous adjustments and the settings of the aids will end up being under target.
  • They will often have normal tymps despite the conductive loss.

Example 1

Example 2

Above are 2 example audiograms. You can see how in case 1 the higher frequencies have been affected (from Collapsed Ear Canal and Sudden Sensorineural Hearing loss) In case 2 which was a severe canal collapse, it has affected all frequencies. Case 2 is exactly one of those cases where multiple investigations occurred before they realised the issue. (from Bilateral Conductive Hearing Loss due to Collapsed Ear Canals in a 35 Years Old Female – MedCrave online).

As we have said previously mass (a canal collapsing over itself) will affect the higher frequencies which is why we see in case 1, the higher frequencies are down. If masked bone had been done on the supra-aural audiogram there would have been an air bone gap. The audiologist in this case realised it was a collapsed canal and then used inserts hence why there is no masking or BC.

In case 2 it’s a complete collapse causing both stiffness and mass and hence why there is an airbone gap across all frequencies. However, it is worse in the higher frequencies this is another clue!

In both cases tympanometry results were showing normal middle ear movement.

What to do if you don’t have inserts?

Not everywhere has inserts. Some people have used speculum to hold the canal open and then put headphones on top. This can be uncomfortable. I have found using tympanometry tips work best (as big as is comfortable). Cut off the flange part of the tymp tip, tie cotton string through it and knot it; and then insert. The cotton string makes taking it out so much easier. Always note on your audiograms that you have found collapsed canals. This ensures that all individuals attending to this client now and in the future are aware of the issue.

 

Let’s fool you audiogram

This audiogram occurred when I was working in the NHS. Whilst it is possible that the loss occurred post operatively. I find that unlikely as the previous audiograms hinted the underlying loss.

As it was a child people suspected it was due to slight inattention/boredom during a hearing test (the child was under 7). As you can see pre-operation both sides have a conductive loss. However, the right side is showing a mixed loss at 2000Hz. Staff though this was a false positive. Look at the audiogram below though, there is a hint that this may be sensorineural, even if the BC is incorrect. Why is the AC dip so much worse than the adjacent frequencies at 2000hz on the right? Tymps were flat in this case.

Pre-operative

Post operative

I strongly suspected that I would get the above audiogram as the 2 previous audiograms had shown the dip in AC & BC at 2000Hz to varying degrees. The dip at 2000Hz is out of proportion to the other frequencies around it, yes it can be fake if it isn’t repeatable to some degree. Given that the dip, stayed in all prior audiograms should have alerted to all that there was potentially an underlying sensorineural hearing loss at 2000Hz on the right. The child reported much better hearing post operatively but still some issues in noise. Needless to say, it was a shock to both the mother and the child. This result did not change post grommets falling out or in later tests. Unfortunately, I wasn’t able to find out the probable cause of the sensorineural dip at this frequency.

I always say if it doesn’t look right, it isn’t right. This dip at 2000Hz was consistent. It is rare for people to fake the similar levels of an audiogram well over a series of hearing tests.

 

The malinger!

Malingering means not giving a true result. There are many different reasons for this. It could be due to attention seeking, psychological issues, misunderstanding instructions, or wanting compensation for their hearing loss. Jerger, in 1981 came up with the below statistics, in brackets are my suggested reasons.

  • 2% of population
  • 7% in children age 6-17 years
  • Typical mean onset of NOHL = 10-12 years (school stress, sibling has hearing loss)
  • Rare below 7 years of age (as children under this age seek approval)
  • Up to 50% of those seeking compensation

So, what type of audiograms would you see?

 Observation

  •  PTA response pattern
  •  Audiometric pattern  –  e.g. flat SNHL or worse than subjective hearing level
  •  Between ear unmasked level difference greater than 70 dB for AC and 10-20 dB for BC
  •  History – a lot can be gained by listening to the patient e.g. sibling with hearing loss, exams coming up, trauma.

 

The above audiogram’s AC thresholds on the right were not yet masked. Therefore, this a malingering audiogram. This is because it isn’t possible for there to be more than a 70dB difference between ears without the good ear (left) helping the bad ear. Therefore, we would expect better AC results on the right pre masking than what we are given above. True hearing test results on the right would be better around 60-70dB and deteriorate when rule 1 of masking is applied (more than 40db difference between AC thresholds). Also why is the BC so good particularly if there is no history that suggests conductive loss.

This is an easy one to spot. However, taking a verbal history with a client tells a lot. For example, if you a getting a moderate to severe sensorineural hearing loss but they can still hear you speak with no hearing aids when you turn away, well that isn’t possible!

Also flatter audiograms are easier to fake than a sloping loss. So we see these more with malingering audiograms.

Remember the above audiograms are examples, variations to these will occur given clients otological history. But hopefully I have given you a good place to start.

Coming soon: Part 3 – Middle ear pathologies such as otosclerosis

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Ear Pathologies and Audiograms: Part 1 (Frequent Offenders)

Our BSA Audiometry course is a great place to start when you wish to learn how to do a basic audiogram. For those of you that are training to be an audiologist then we offer a masking course too. Please look at our training calendar for dates for these Training Calendar – TJ Audiology Training. We will soon be offering masking theory as an online tutorial, through a portal accessed from our webpage (watch this space)

So, you understand how to do an audiogram but what do the results mean? What are they telling me? When I started audiology 30 years ago, we had a great text book by James Jerger called Clinical Audiology (easier to read than Katz!!) that gave you both audiograms and tympanograms for different types of hearing loss and this helped give you a starting point. Its long out of print now. However, we still regularly use his classifications for our tympanograms.

I am not going to explain an audiogram graph and the different symbols (AC: Air Conduction and BC: Bone Conduction) and degrees of loss, I am assuming that you already have this knowledge! Let’s, start simple and then get more complex (because there is so much information to give this will be an ongoing series). Remember the list is not exhaustive and you will get people that don’t fit the normal pattern. This is why the BAA Onward referral guidance – British Academy of Audiology |British Academy of Audiology has red flags for referral onto ENT, include other audiological issues such as dizziness, tinnitus and facial palsy, not just the audiogram.

Normal Hearing

Please note if hearing is normal but there are other red flags such as dizziness or unilateral or pulsatile tinnitus onwards referral will be required (if these red flags are present for any of the hearing loss below then onwards referral to ENT will still be needed). You would generally expect normal tympanometry results.

Sensorineural Hearing Loss

Sensorineural. The triangles which are the bone conduction results are within 10dB of the air conduction thresholds indicating that this is a mild to moderate sensorineural hearing loss. You would generally expect normal tymps with this loss.

Noise Induced Hearing Loss

With a noise induced loss you will see a dip between 3-6kHz and then upwards improvement and the BC results within 10dB of the AC (only AC shown on these examples). However, as a client ages, then you add an age-related loss on top or increasing noise exposure (as shown in the 2nd graph) then the proportions will change. You would generally expect normal tymps.

Glue Ear

Glue ear is often found in children under the age of 7-9. The eustachian tube is narrower and flatter than in an adult. Children under this age are more likely to suffer from Glue ear/Otitis Media as the eustachian tube is unable to drain as effectively.

The audiogram with show reduced hearing through the headphones (AC), but the bone conduction results (BC) will be within the normal range. (20db or less if there is no underlying sensorineural hearing loss). You will either have a flat tymp or negative middle ear pressure for the reasons explained below.

The audiogram gives a flatter presentation when the middle ear is so fluid filled that both mass (how much mass is there in an object) and stiffness (how stiff the object is) are being affected. Stiffness affects the lower frequencies and mass the higher frequencies. If there was some draining or improvement in the glue ear than you would see the higher frequencies improve. (as there is now less mass)

Tympanosclerosis

Tympanosclerosis is scaring on the eardrum. The scarring occurs either from perforations that have healed or from having had grommets. The amount of scarring will be dependent on the amount of irritation and bleeding that has occurred during these events.  Scarring will cause the eardrum’s movement to be stiffer. Stiffness as we said earlier will affect the lower frequencies as shown in the audiogram. Tymps may show restricted or shallow movement.

Perforation

Remember this is an example audiogram and your audiograms may differ . In this case the client already has an underlying sensorineural hearing loss (the BC is out of the normal range).  The degree of conductive component of the loss will be dependent on how the perforation affects the transmission of sound from the middle ear space to the cochlea. As for tympanometry you will have either a flat tymp with a large canal volume or you will not be able to obtain a seal. Below is another audiogram example for a perforation where the squiggly lines (masked BC are within normal and the AC is down).