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Non-Organic Hearing Loss (NOHL) is a fairly common presentation in service patients who feign hearing loss to avoid service obligations and for personal and economic gains. The aim of this article is to stress the importance of having a high index of suspicion to weed out such cases and to highlight the utility of simple unaided hearing tests, which have been lost in the ocean of technological advancement in detecting NOHL. These tests have been retrieved from literature and have been described in detail as they are simple enough to be adopted even by general practioners.
A 35-year-old male patient in Cat CEE (permanent) for CSOM (L) effects of, reported to the ENT OPD for recategorisation. The onset of his disease was in 1995 when he developed otalgia in left ear followed by blood stained otorrhoea which subsided after treatment. Thereafter he complained of persistent hearing loss and tinnitus in left ear. There was no vertigo or headache and no nasal or throat complaints. There was no h/o noise exposure, intake of ototoxic drugs, trauma or any systemic disease. Examination of the ears revealed intact and mobile tympanic membranes without scarring or signs of any healed perforation. Tuning fork tests were inconsistent. Neurotological examination was normal. Nose and throat revealed no abnormality. An unconvincing history, normal appearance of tympanic membrane and variable tuning fork tests aroused suspicion regarding possibility of non organic hearing loss. He was then subjected to a battery of simple audiological tests since no sophisticated tests were available. Erhards tests and Lombards tests indicated non organic loss, Chimani Moos and Stenger tests lent more credence to our suspicion. Audiometry showed inconsistent responses. The behaviour of the patient in the ward was also observed. As the diagnosis of NOHL was confirmed the patient was directly confronted and he confessed to having no disability and accepted he was a malingerer.
Non-organic hearing loss (NOHL) may be either psychogenic, feigned or artefactual when there is either inattention or misunderstanding of the audiometric task . A large number of tests have been described to detect NOHL. These tests vary from simple speech and audiometric tests to the sophisticated electrophysiological tests.
Evaluation of a patient with suspected NOHL proceeds in a systematic manner and starts on first contact with the patient.
Observation of the general behaviour of the patient provides vital clues regarding the nature of hearing loss. The general attitude of those with feigned deafness is one of very obvious exaggerated hearing loss and there is no change in their voice which remains at normal intensity. There is lack of eye contact and discrepancies in observing lip movements. Observing the patients at informal times and checking the volume of the hearing aid if they are using one at these times is helpful.
Many simple tests have been described to detect non-organic hearing loss.
Chimani, Moos, Stengers and Teals test are very useful in detecting non-organic hearing loss. Teals test is used in patients who claim to hear only by bone conduction. Tuning fork is first placed on the mastoid process and the person hears, then non vibratory fork is placed on the mastoid and vibratory fork in front of the ear to confuse the patient about the source of the sound.
A large number of objective tests have been in use. Some of them like EEG audiometry which recorded change in EEG from sleep pattern to awake pattern on application of sensory auditory stimuli and Electrodermal and Psychogalvanic audiometry which measured changes in skin resistance on introduction of pure tones have now become obsolete and have been replaced by more reliable and objective tests like acoustic reflex threshold and brain stem evoked response audiometry which are currently the best tests available to detect NOHL. Two tests currently in the realm of development and research may be the best modalities available in future to detect nonorganic hearing loss.
There is a relationship between flow of electrical currents in nerves and the magnetic field associated with this flow. Thus exploration of this magnetic analogue of auditory evoked potential though yet not of proven clinical utility may prove to be useful after intensive research .
Otoacoustic emissions generated by the cochlea and recorded in the external auditory meatus of normal hearing person have the potential to provide insight into the type of hearing loss .