London - We all know that some things can affect our hearing - working in a noisy environment, for instance, or diseases such as mumps and measles.
But recently, a lesser-known risk has surfaced; passive smokers have been found to be twice as likely as other people to suffer from hearing loss.
Sensorineural hearing loss, which usually occurs with age, is caused by damage to the sensory cells of the cochlea, the snail-shaped hearing organ of the ear that is responsible for converting the mechanical vibration of sound into electrical signals, which go on to be detected by the brain.
Passive smoking is thought to affect our hearing in a number of ways. Nicotine and carbon monoxide from cigarettes can deplete oxygen supply to the ear. Nicotine also impairs the messages sent by neurotransmitters in the hearing nerve. “The ear is an extremely delicate organ and far more susceptible to damage than you might think,” says David McAlpine, professor of auditory neuroscience and director of the University College London Ear Institute.
So what other unusual factors could also cause temporary or permanent hearing loss? We asked the experts .....
VIAGRA
In an American study of more than 11,000 men who were more than 40 years old, those who took Viagra or a similar drug were twice as likely to report hearing loss as those who had not used the drug.
It’s thought these drugs, which increase blood flow to certain tissues in the body may have a similar effect on tissue in the ear, potentially causing damage that leads to permanent hearing loss, says Professor Gerald McGwin, of the University of Alabama at Birmingham School of Public Health.
STROKE
Generally caused when a blood clot obstructs blood supply to the brain, strokes can lead to paralysis, communication problems - and even problems with swallowing.
But if the stroke occurs in the front temporal lobe in the brain - the bit under your forehead (which deals with perception, hearing and memory), it can also cause hearing loss because the blood supply to the delicate inner ear is stopped, says Professor McAlpine.
Interestingly, sudden hearing loss could also be a warning sign of increased stroke risk.
Taiwanese researchers found that patients who suffered sudden significant hearing loss - developing rapidly within 72 hours - were one-and-a-half times more likely to have a stroke in the five subsequent years afterwards.
It’s thought the blood supply issues which caused the hearing loss could point to similar problems happening elsewhere.
DYSLEXIA
Most people think of dyslexia as a problem with reading, but a study published recently in the journal Science suggests it may also affect the brain’s ability to process sound. Researchers at the Massachusetts Institute of Technology found people with dyslexia have trouble recognising voices and matching them with the right faces.
Experts think this could explain why dyslexics can mix words up - rather than being a problem with understanding the meaning of words, it’s related to problems recognising the sounds of speech.
CHEMOTHERAPY
Platinum-based chemo drugs, such as cisplatin - used to treat testicular, ovarian and bladder cancers - can also cause hearing loss as a side-effect.
An Oregon Health and Science University study found that 61 percent of 67 patients being treated with platinum-based chemotherapy suffered hearing loss - with average onset being 135 days after treatment. “The drugs damage the tiny cells in the inner ear that vibrate in response to sound waves,” says Professor McAlpine. “This can lead to progressive, irreversible hearing loss, so cancer and ear specialists often work together monitoring hearing and changing drugs if necessary.”
FOOD ALLERGIES
Food allergies commonly trigger rashes, but can also affect your hearing. In a study carried out at Georgetown University School of Medicine, 78 percent of those suffering from otitis media (or “glue ear”) suffered from a food allergy.
“Glue ear is particularly common in children,” says George Murty, consultant ear, nose and throat specialist at University Hospital Leicester. “Normally, the space behind the eardrum - which allows the transmission of sound, is filled with air, but with an allergic reaction, where the immune system goes haywire, it can fill up with fluid.
“When the allergy eases, the fluid generally drains out, but this doesn’t drain particularly well in children. Antibiotics or a small operation are sufficient to ease the problem.”
TICK BITES
Tick bites can spread Lyme Disease, an increasingly common infection more likely to occur in spring and early summer.
Early symptoms include a rash, flu-like symptoms and joint pain. It is diagnosed with a blood test, however if the condition is untreated, within a week or so chronic symptoms such as hearing loss, headaches, muscle pain and dizziness can occur. It’s thought the hearing loss occurs as a result of the bacterial infection damaging the sensitive inner ear.
“Treated with antibiotics, the hearing problems are reversible - there should be an improvement within a few weeks,” says Mr Murty.
ANTIBIOTICS
A type of antibiotics known as aminoglycosides - used to treat severe infections such as tuberculosis or septicaemia - can strip out hair cells in the inner ear, causing permanent hearing problems says Professor McAlpine.
A study at the Institute of Child Health, London, found some patients may have a genetic mutation making them even more prone to suffer hearing loss after taking these antibiotics. About one in 40,000 people in the UK have this mutation, which causes around five per cent of deafness in children in the UK.
Families carrying this mutation may develop some degree of deafness later in life.
SHINGLES
This painful condition - caused by the herpes varicella zoster virus - is an infection of the nerve and the area of skin around it.
“Although the chest is most commonly affected, sometimes it affects the nerves in the head - including the hearing nerves - a condition known as Ramsay-Hunt Syndrome,” says Mr Murty. Along with hearing loss this can lead to paralysis of the face (Bell’s Palsy), dizziness and vertigo.
It’s important to start the treatment as soon as possible. Even a delay of only a few days in starting treatment could result in hearing loss, affecting around one in 20 people who have the condition.
MALARIA DRUGS
Everyone knows the importance of taking anti-malarial drugs, but one type in particular - quinine - has a rare but unpleasant side-effect. Given to hundreds of thousands of people each year, quinine can also cause hearing loss.
Although it’s rare and caused by an extreme reaction to the drug, it can go on to damage the sensory hairs on the cochlea, disrupting the electrical impulses to the brain, which normally enable us to hear, says Mr Murty.
DIABETES
Hearing loss linked to diabetes is more common you might think. “Just as diabetes can damage the nerves and blood vessels throughout the body - it may also occur in the ear,” says Professor McAlpine.
More complications include foot ulcers and heart disease and retinopathy, where blood vessels in the retina of the eye become blocked. - Daily News
* Visit deafnessresearch.org.uk