Deafness
Causes
There is no strict order in the list featured in Table 4.1, because the frequency with which various causes of deafness occur varies from one community to another and from one age group to another. Nevertheless, some indication is given by division into ‘more common’ and ‘less common’ groups. Some deterioration in hearing acuity is a normal feature of aging (presbycusis), sometimes associated with tinnitus or ‘noises in the ear’. Always try to make a diagnosis of the cause of deafness and strt by deciding whether it is conductive or sensorineural.The deaf child
The commonest cause of deafness in children is fluid in the middle ear due to otitis media. This causes a temporary conductive deafness.
Sensorineural loss is rare (one in a thousand newborns) but nearly always perma- nent. In most Western countries newborn babies are screened for deafness ‘universal screening’ and delayed diagnosis is becoming less common. Late diagnosis is still all too frequent in poorer countries and doctors and other health care workers need to be alert to the need to refer children early if there are concerns about the child’s hearing. Early diagnosis of deafness in babies is essential to avoid irretrievable delay in language development. The mother’s assessment is important; if parents or carers are concerned about a child’s hearing you need to refer the child for full investigations.
Some babies are particularly ‘at risk’ of deafness. They include those with:
• prematurity and low birthweight;
• perinatal hypoxia;
• syndromes and chromosomal abnormalities;
• severe jaundice;
• family history of hereditary deafness;
• intrauterine infections such as Toxoplasma, Rubella, Cytomegalovirus Herpes and HIV (TORCH infections).
Sensorineural loss is rare (one in a thousand newborns) but nearly always perma- nent. In most Western countries newborn babies are screened for deafness ‘universal screening’ and delayed diagnosis is becoming less common. Late diagnosis is still all too frequent in poorer countries and doctors and other health care workers need to be alert to the need to refer children early if there are concerns about the child’s hearing. Early diagnosis of deafness in babies is essential to avoid irretrievable delay in language development. The mother’s assessment is important; if parents or carers are concerned about a child’s hearing you need to refer the child for full investigations.
Some babies are particularly ‘at risk’ of deafness. They include those with:
• prematurity and low birthweight;
• perinatal hypoxia;
• syndromes and chromosomal abnormalities;
• severe jaundice;
• family history of hereditary deafness;
• intrauterine infections such as Toxoplasma, Rubella, Cytomegalovirus Herpes and HIV (TORCH infections).
Table 4.1 Causes of deafness
|
||
Conductive
|
More common
|
Less
common
|
Sensorineural
|
Wax, acute
otitis media, middle
ear
effusion, otosclerosis, perforated eardrum.
Presbycusis (deafness with
advancing age); noise-induced; congenital – may be genetic or due to maternal infection such as toxoplasmosis, rubella, cytomegalovirus; neonatal pathologies e.g. jaundice, prematurity, hypoxia; infections in childhood
e.g. mumps, meningitis, measles;
drugs,
e.g. aminoglycosides, quinine, aspirin
|
Middle ear trauma,
congenital middle ear pathology, tumours
Vestibular nerve
tumour; head injury; CNS disease, e.g. multiple sclerosis, metastases; metabolic disorders, e.g. diabetes mellitus, hypothyroidism |
Children with normal hearing at birth can become deaf in early childhood due to infections such as measles and meningitis.
Presbycusis
Some deterioration in hearing is almost inevitable as patients get older (presbycusis). This starts in early adult life and affects first the high tones. As many as 70% of patients in their seventies could benefit from the use of a hearing aid, and many patients from their forties onward will have marked age related hearing loss. This is caused mainly by loss of sensitivity of the delicate hair cells in the cochlea. It is usu- ally bilateral but the pattern is very variable.
Otosclerosis
Otosclerosis causes abnormal bone to be formed around the stapes footplate, preventing its normal movement. Conductive deafness results. It is commoner in wom- en, typically presents in early adult life and often progresses during pregnancy. There may be a family history. Apart from conductive deafness, evident on tuning fork tests (Chapter 3), examination is typically normal. Otosclerosis can be treated by surgical removal of the stapes and replacement with a prosthesis (stapedectomy). This is a highy specialized procedure with a risk of complete hearing loss in the operated ear.
Sudden sensorineural deafness
Sudden deafness may be unilateral or bilateral and most cases are regarded as being viral or vascular. Sudden sensorineural deafness is an emergency and should be treated seriously. Bilateral profound deafness, especially if sudden, is a devastating event. Arrange admission to hospital as delay may mean perma- nent deafness.
Investigation may show no cause and treatment is usually with low molecular weight dextran, steroids and inhaled carbon dioxide in an attempt to improve blood flow to the inner ear, although there is no good evidence that these strategies are effective.
Investigation may show no cause and treatment is usually with low molecular weight dextran, steroids and inhaled carbon dioxide in an attempt to improve blood flow to the inner ear, although there is no good evidence that these strategies are effective.
Vestibular Schwannoma (acoustic neuroma)
Vestibular Schwannoma is a benign nerve tumour in the internal auditory mea- tus or cerebello-pontine (CP) angle at the base of the skull. It is usually unilateral, except in the very rare familial neurofibromatosis type 2 (NF2), when it may be bilateral. In its early stages, it causes progressive hearing loss and imbalance. As it enlarges, it may encroach on the trigeminal nerve in the CP angle, causing loss of corneal sensation. In its advanced stage, there is raised intracranial pressure and brain stem displacement. Early diagnosis reduces the morbidity and mortal- ity. Unilateral sensorineural deafness should always be investigated to exclude a neuroma. Audiometry will confirm the hearing loss. MR scanning will identify even small tumours (Fig. 4.1).
Hearing aids
Hearing aids work on the principle of amplifying sound. In the typical ‘behind the ear’ aid a small microphone picks up sound which is then amplified electronically and fed into the ear by an earpiece or mould customized to fit the patient’s ear canal. The amplifier is housed behind the ear. More sophisticated (and expensive) are the ‘all in the ear’ aids, where the electronics are built into a mould made to fit the patient’s ear. Some patients prefer these as they are inconspicuous. They give good di- rectional hearing and, because they are individually built, the output can be matched to the patient’s deafness. Modern hearing aids are digital, allowing more refinement in the sound processing and more control of the aid. Even with good amplification there can be problems with clarity for many deaf patients. In cochlear forms of sen- sorineural deafness, loudness recruitment is often marked (see Chapter 3, p.16). This results in an intolerance of noise above a certain threshold, making amplifi- cation very difficult. Many modern hearing aids are fitted with a special electronic circuit a loop inductance system to make the use of telephones easier (Fig. 4.2).
Bone-anchored hearing aids
Some patients are unable to use a conventional hearing aid because of the shape of the ear canal or due to chronic infection. They may be suitable for a bone-anchored hearing aid (BAHA). A titanium screw is threaded into the temporal bone and al- lowed to fuse to the bone (osseo-integration). This allows the attachment of a special hearing aid that transmits sound directly by bone conduction to the cochlea (Fig. 4.3).
Cochlear implants
These rely on the implantation of electrodes into the cochlea to stimulate the auditory nerve. The apparatus consists of a microphone, an electronic sound processor and an electrode implanted into the cochlea. Cochlear implantation is only appropriate for bilateral profound deafness. Results can be spectacular, with some patients able to converse easily. Most patients obtain a significant improvement in their ability to communicate (Fig. 4.4).
Lip-reading
Instruction in lip-reading is much more effective while usable hearing persists and should always be offered to those at risk of total or profound deafness.
Sign language
Many deaf children and adults learn to communicate very effectively by sign language. The major types in the UK are British Sign Language (BSL), Sign Supported English (SSE), tactile signing systems (e.g. the deafblind manual alphabet), and Makaton (see http://www.nhs.uk/CarersDirect/guide/communication/Pages/ Signlanguage.aspx).
References
·
World Health Organization
(WHO):
World Health Organization. (2026). Deafness and hearing loss factsheet.
World Health Organization.
https://www.who.int/news-room/fact-sheets/detail/deafness-and-hearing-loss
·
StatPearls (NCBI Bookshelf):
Bae, C., & M Das, J. (2025). Hearing loss and deafness: Etiology, types,
and clinical evaluation. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK542323/
·
National Institutes of Health (NIH - NIDCD):
National Institute on Deafness and Other Communication Disorders. (2024). Quick
statistics about hearing, deafness, and balance disorders. NIDCD. nih.gov
·
Cleveland Clinic:
Cleveland Clinic Medical Staff. (2024). Sensorineural hearing loss and
profound deafness: Causes, symptoms & treatment. Cleveland Clinic. clevelandclinic.org
·
Medscape:
Nadol, J. B., & Meyers, A. D. (2025). Hearing impairment and deafness
pathology and management. Medscape Drugs & Diseases. medscape.com
Medical Disclaimer
Important Notice: This article is provided for educational and informational purposes only and does not constitute medical advice, diagnosis, or treatment. The content is based on current medical literature and guidelines but should not replace professional medical consultation.
Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking it because of something you have read in this article. If you think you may have a medical emergency, call your doctor or emergency services immediately.
Individual responses to treatments may vary. What works for one person may not work for another. Treatment decisions should be made in consultation with qualified healthcare professionals who can evaluate your specific situation.
