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About Hearing Loss

About Hearing Loss

Types and causes of hearing loss and deafness

Overview

Hearing loss and deafness happen when sound signals don’t reach the brain. This is caused by a problem in the hearing system. There are two main types of hearing loss. It’s possible to have both types, and this is known as mixed hearing loss.

This is caused by damage to the hair cells inside the inner ear, or damage to the hearing nerve, or both. It makes it more difficult to hear quiet sounds and reduces the quality of sound that you can hear. Sensorineural hearing loss is permanent, but can often be treated with hearing aids.

This happens when a blockage, such as ear wax, stops sound passing from your outer ear to your inner ear. Sounds will become quieter and things might sound muffled. It can be temporary or permanent. Conductive hearing loss is usually caused by ear problems.

Age-related hearing loss

Age-related damage to the inner ear is the single biggest cause of hearing loss. It’s also known as presbycusis. Most of us will experience some level of hearing loss as we get older. This type of hearing loss tends to affect both ears, and increases as you get older.

The main cause of age-related hearing loss is gradual wear and tear to tiny sensory cells called ‘hair cells’ in the cochlea (your hearing organ in the inner ear).

Your hearing might start to deteriorate with age, which makes high-frequency sounds, such as some voices, difficult to hear. It might also be harder to hear ‘s’, ‘f’ and ‘th’ sounds in words. This can make it hard to understand what people are saying over background noise. There is no cure for age-related hearing loss, but many people find hearing aids to be a huge help.

You may be experiencing hearing loss if you:

  • think other people sound like they’re mumbling
  • ask people to repeat things for you often
  • have difficulty understanding what is being said in noisy places
  • find it hard to keep up with group conversation
  • get tired from having to concentrate so much
  • find other people think your TV or music is too loud
  • often have difficulty hearing on the telephone.

Sudden hearing loss

Sudden hearing loss can affect one or both ears. It can happen instantly or over the course of a few weeks, and you might also have tinnitus or balance problems. Recovery from sudden hearing loss will depend on the cause and how badly you’re affected.

If you suddenly lose hearing in one or both ears, you should contact NHS 111 or your GP as soon as possible. Your hearing loss might not be serious, but it can be a symptom of a medical emergency. If this is the case, there is a very short window of time for treatment. If you can’t see your GP or call NHS 111 for any reason, go to your nearest accident and emergency department. At the hospital, an ear, nose and throat (ENT) specialist will carry out tests to find out what degree and type of hearing loss you have. You may need to stay in hospital for treatment, or you may be treated as an outpatient.

Causes can include:

  • ear wax
  • infections
  • trauma
  • ototoxic drugs
  • acoustic neuromas
  • Ménière’s disease

Noise-induced hearing loss

Exposure to loud noise is the second biggest cause of hearing loss. You might not notice the effects of noise-induced hearing loss until years after you were first exposed to loud noise. Some people experience tinnitus as the first sign that their hearing has been damaged by noise.

Noise-induced hearing loss is caused by being around very loud noises for a long time. This could include:

  • being in a noisy workplace
  • listening to loud music
  • loud bursts of sound, like gunshot or explosions.

Noise levels are usually measured in dB(A), which is a decibel scale that mirrors the sensitivity of human ears to different levels and pitches of sound.

  • Long exposure to sounds over 80dB(A) can damage your ears.
  • In a real-life situation, you should be able to talk to someone who is 2 metres away without having to shout over background noise. If you can’t be heard over the background sounds, the noise levels could be hazardous.
  • If you go somewhere where the sound level hurts your ears, you should leave.

If you have hearing loss caused by exposure to noise, you will experience a dip in your hearing in the high frequencies. This means you won’t be able to hear high-pitched sounds as well as sounds at lower pitches.

If the noise exposure carries on, this dip will spread and affect both lower and high frequencies.
If it gets worse and affects a wider frequency range, you might find it difficult to follow conversations over background noise. You might also find it hard to hear what someone is saying, even in a quiet room.

To prevent noise exposure, it’s best to avoid loud sounds at work, at home or when you go out. There are steps you can take to protect your hearing.

There is no cure for noise-induced hearing loss, but many people use hearing aids to hear better in everyday situations.

Genetic hearing loss and deafness

Some types of deafness can be inherited. In the UK, about one in 1,600 children is born moderately to profoundly deaf because they inherit a mutated gene. If you are deaf or if hearing loss runs in your family, genetic information may help identify the cause of your condition. It may also identify whether you are likely to have a child who is deaf. The chances of developing deafness caused by a mutated gene depends on whether the gene is dominant or recessive.

A dominant gene mutation that causes hearing loss can come from the mother or the father. The chance of passing on this mutation to your children is one in two.

Dominant genes don’t have the same effect on everyone. In one family, a gene can cause profound deafness in one person and mild deafness in another. Sometimes, it may not affect a person’s hearing at all.

A dominant gene mutation may have been in a family for generations, but it can also appear for the first time in a family without a history of deafness.

A recessive gene mutation that causes deafness in a child must have been passed on by both the mother and father. If the child only inherits one copy of the affected gene from one parent, they’ll be a carrier. This means that although they can hear, they can pass on the affected gene to their own children. A person who is deaf due to a recessive mutation may have parents who are hearing. They may also have brothers and sisters who are both hearing and deaf, and no family history of deafness even though the deafness is genetic.

Most of our genes are in our chromosomes, but some are found in structures called mitochondria. Mitochondria are in the cells of our bodies and are inherited from our mothers. This means that if deafness is caused by a mutation in a mitochondrial gene, only women can pass on deafness to their children. However, both men and women can have this type of deafness.

If you are deaf, or if deafness runs in your family, genetic information may be helpful to:

  • find out the chances of having a child who is deaf
  • try to identify the cause of your deafness
  • look for medical conditions that might be associated with your deafness.

About 30% of deafness in young children is associated with other medical conditions or syndromes. For example, someone with Usher syndrome has deafness from birth and loses their sight gradually.

You can get information about genetics and deafness by having a consultation in a genetic clinic. This consultation is called genetic counselling. Genetic counselling is free on the NHS, but you need to be referred by your GP, paediatrician, ear, nose and throat (ENT) consultant or audiologist.

In the future, many more genes may be discovered that are needed for hearing. The genes discovered so far mainly cause deafness in childhood or young adulthood. However, deafness in older people could be due to genetic inheritance too. Researchers are beginning to discover which genes cause age-related hearing loss. This might mean people who are at risk of losing their hearing can be identified, and can take steps to protect their hearing.

Ototoxic drugs and hearing loss

Drugs that can cause damage to the inner ear, which can cause hearing loss, balance problems or tinnitus, are called ototoxic. There are over 100 prescription and over-the-counter drugs that are linked with hearing loss. Usually, there is only a risk to your hearing if you’re taking very large doses, or very strong drugs, such as to treat cancer.

You should talk to your doctor if you think that a drug you are taking is:

  • causing hearing loss
  • causing balance problems
  • causing tinnitus
  • making existing hearing loss worse.

You should not reduce your dose or stop taking the medication altogether without speaking to your doctor. Your doctor may be able to prescribe you a different drug that won’t affect your hearing in the same way. If this isn’t possible, you should ask your doctor’s advice and decide whether the benefits of taking the drug outweigh the possibility of permanently damaging your hearing.

If aspirin is taken in its correct dose, it’s very unlikely to cause side effects.

If it’s taken in a large dose or an overdose, aspirin can sometimes cause temporary tinnitus, dizziness and nausea.

There is little evidence that aspirin causes permanent hearing loss.

The group of antibiotics that is most likely to cause hearing loss is called aminoglycosides. These include:

  • gentamycin
  • streptomycin
  • neomycin.

These antibiotics are often used to treat serious or life-threatening bacterial infections such as tuberculosis (TB). If you have been prescribed aminoglycosides, you should have been made aware of the risk of permanent damage to your hearing. The effects will usually be monitored by regular blood tests to see how much of the drug is in your bloodstream.

Drugs that are used for treating cancer are called cytotoxic drugs. Cytotoxic drugs destroy cells or prevent their regrowth. This usually happens through chemotherapy. These drugs attack healthy cells as well as cancerous ones, so they can cause a number of side effects.

Types of cytotoxic drugs that can cause hearing loss are:

  • carboplatin, which is mainly used to treat ovarian and lung cancer
  • cisplatin, which is mainly used to treat ovarian, testicular, lung or bladder cancer
  • oxaliplatin, which is mainly used to treat bowel cancer.

Cytotoxic drugs are often used in combination with other drugs, which can affect how much hearing loss you experience.

If you are prescribed cytotoxic drugs, the effects will be carefully monitored. You should tell your doctor immediately if you are taking them and you:

  • develop tinnitus
  • start to feel unsteady

have difficulty hearing.

Any of these can be the first sign of hearing loss caused by ototoxic drugs.

Diuretics are drugs that increase the amount of urine you produce. They’re also used to treat high blood pressure and conditions where fluid builds up in the tissues, such as heart and kidney failure, and some liver diseases. Only a type called ‘loop’ diuretics are known to cause hearing loss, and are usually only ototoxic when they’re given in large doses in life-threatening situations. If you already have hearing loss and balance problems, you should make sure your doctor is aware. This means you can receive treatment from diuretics that do not have ototoxic side effects.

Some common side effects of antimalarial drugs include:

  • tinnitus
  • headaches
  • nausea
  • dizziness
  • sleep disorders
  • anxiety
  • depression.

In rare cases antimalarial drugs called chloroquine and quinine can cause hearing loss, although there isn’t enough evidence around this yet. The risks of any side effect from antimalarial drugs may be bigger if you actually get malaria, and are given high doses to treat the disease. You should talk to your doctor if you’re about to travel to an area where malaria is common, and are concerned about the possible side effects of antimalarial drugs.

Acoustic neuroma

An acoustic neuroma is a rare, slow-growing tumour that presses on the hearing and balance nerves. It’s treatable and it’s benign, which means it is not cancerous.

An acoustic neuroma grows very slowly over a number of years. Eventually it presses on the balance, hearing and facial nerves, which means it can affect hearing and balance. If it becomes very large it can press against the brain, although this doesn’t happen very often thanks to modern diagnostic techniques.

An acoustic neuroma may not have obvious symptoms at first. Symptoms will often develop gradually and can include:

  • hearing loss
  • tinnitus
  • vertigo.

A large acoustic neuroma can also cause:

  • persistent headaches
  • temporary blurred or double vision
  • numbness, pain or weakness on one side of the face
  • problems with limb coordination on one side of the body
  • a hoarse voice or difficulty swallowing.

Speak to your GP and get a referral to the hospital for an assessment if you have any of the symptoms. Other conditions, such as Ménière’s disease, have some of the same symptoms. A specialist will check for an acoustic neuroma to make sure you’re treated properly. If the specialist thinks you may have an acoustic neuroma, you will likely have:

  • your hearing assessed
  • an MRI (magnetic resonance imaging)
  • a CT (computerised tomography) scan.

If you’re diagnosed with an acoustic neuroma, your treatment will depend on a number of things, including:

  • your general health
  • the size and position of the tumour
  • results of other tests.

It’s best to discuss treatment options in detail with your surgeon or radiotherapist.

Acoustic neuromas grow very slowly so there’s no need to rush into a choice of treatment. All treatments happen at specialist centres, and include:

  • observation
  • microsurgery
  • radiotherapy
  • radiosurgery

Treatments can have some side effects. For example, surgery and radiosurgery can sometimes cause facial numbness or paralysis. It’s important to speak to your doctor about the best option for you, and what the benefits and risks are.

Diuretics are drugs that increase the amount of urine you produce. They’re also used to treat high blood pressure and conditions where fluid builds up in the tissues, such as heart and kidney failure, and some liver diseases. Only a type called ‘loop’ diuretics are known to cause hearing loss, and are usually only ototoxic when they’re given in large doses in life-threatening situations. If you already have hearing loss and balance problems, you should make sure your doctor is aware. This means you can receive treatment from diuretics that do not have ototoxic side effects.

Some common side effects of antimalarial drugs include:

  • tinnitus
  • headaches
  • nausea
  • dizziness
  • sleep disorders
  • anxiety
  • depression.

In rare cases antimalarial drugs called chloroquine and quinine can cause hearing loss, although there isn’t enough evidence around this yet. The risks of any side effect from antimalarial drugs may be bigger if you actually get malaria, and are given high doses to treat the disease. You should talk to your doctor if you’re about to travel to an area where malaria is common, and are concerned about the possible side effects of antimalarial drugs.

Original content rnid.org.uk