Hearing loss in adults

We commend Edmiston and Mitchell's article on initial assessment of hearing loss in adults, which is particularly timely for something incredibly common yet often overlooked. According to the team looking into hearing and visual impairment in the UK Biobank data, there are an estimated 10 million people affected by hearing loss in the UK, with predictions that this will rise to 14.5 million by 2013. There tends to be greater risk on lower socio-economic groups and the ageing population.

At present rates hearing loss is set to be in the top ten diseases affecting the population by 2030. It is estimated that around 22% of the population are affected by a moderate or worse level of hearing impairment between the ages of 41-70 and yet only around 2.9% use hearing aids. This figure has barely changed since the 1980’s despite advances in technology drastically reducing size and is likely further compounded by the general stigma that still exists with use of hearing aids in comparison to visual impairment and use of optical correction for example.

Given that there is a general reluctance to attend services in the first place and overall under-reporting of hearing impairment, by the time the family physician is attended there may have been considerable time period from onset of symptoms. There is often psychological distress at the breakdown of communication within social circles. Due to the hidden nature of the impairment, it is often deemed perfectly acceptable to aggressively chastise the affected parties by irritated friends and relatives.

Additionally it is also important to remember that the degree of impairment does not necessarily predict the level of disability. In part this is testament to the major part multiple levels of integration and modulation from brainstem to cortex play in processing of auditory information. Certainly we are now increasingly aware of a not insignificant cohort of patients who have functional difficulties despite apparently “normal” audiograms with problems occurring at higher processing stages (and for whom rehabilitation with hearing aids may not necessarily be appropriate). In the case of the UK Biobank project this is reflected by choice of screening with “speech in noise” tests for assessment. It is for this reason that as Audio-vestibular physicians we advocate a multi-pronged holistic approach to best tailor rehabilitation strategies in a manner acceptable to the individual.

On a practical basis this presents a potential practical difficulty for the family physician in that situational difficulties may not be immediately evident via crude screening tests such as the “whisper test” alone. One of the significant limitations of this in the GP surgery environment is that room acoustics are unlikely to be ideal. The room shape and dimensions can have a profound impact on different frequencies, with resonance effects potentially amplifying or reducing sound levels in the order of 20-30 dB in extreme cases (an agonising problem well known to any home recording enthusiasts). In essence a mere change of position by a couple of centimetres may be enough to completely negate any potential accuracy of threshold detection in an uncontrolled environment.

There are a couple of potential ways to minimise this. Action on Hearing loss (formely RNID) have web based and smartphone versions of the “speech in noise” screening tests accessible from their site. Where this is not possible, minimisation of room acoustic factors can be part;y achieved by ensuring positioning of the patient away from walls or corners of a room more towards the centre. Where possible using the long axis of the room, would also be beneficial. This phenomenon also serves to highlight the importance of the role of behavioural strategies to allow a multi-faceted approach to auditory rehabilitation. In practice this means we see a wide range ability to compensate and ultimately the decision to wear hearing aids and adaptation of lifestyle is a complex journey for each individual.

It is also worth remembering that the proliferation of 3rd party high street providers means that accessibility to formal audiometric testing is also increasing. Of course caution should remain that quality of service does not become sacrificed to pecuniary interests, as they have limitations in terms of diagnostic capabilities and management of more complex cases. However aggressive marketing strategies to build up this sector in a similar model to optical correction is underway, so it is likely that GP’s will increasingly find patients attending with audiograms.