For those of us born with it, our hearing is something we take for granted. Which is why, its loss can come as such a shock. Every year, people all over the world discover they are victims of sudden hearing loss. Some will notice it first thing in the morning, others only when they try to use their impaired ear. Still others will hear an alarmingly loud popping sound followed by a sudden silence that refuses to lift.
Dr. Sobitha Abeyaratne, Consultant ENT surgeon sees many such cases each year. He knows that the problem could lie anywhere along the line – from the delicate inner bones in your ear that transmit vibrations to the part of the brain that translates nerve impulses as sounds. The trick lies, as it so often does, in seeking help early enough for the intervention to be successful.
Hearing: A critical sense
“Sound is actually a pressure wave that reaches the ear through the air,” says Dr. Abeyaratne, explaining that slow vibrations are caused by deep sounds, while quick vibrations are generated by high pitched sounds. Sound first enters your ear through a funnel shaped outer section and is then channelled through the narrow external ear canal and into the ear drum, which vibrates when it receives it. Waiting, next in line are the three small bones known as the hammer, anvil and sterrup – collectively dubbed the ossicles. Together they form the ossicular chain.
The vibrations funnelled in from the outer ear, trip down the chain and into the inner ear where the cochlear waits to receive them.
The cochlear is the central organ of hearing in the inner ear. “It is a bony spiral tube filled with fluid, this fluid vibrates causing the sensory cells in the cochlear to be stimulated,” says Dr. Abeyratne. “This results in the conversion of the mechanical energy of the sound waves into complex electrical signals. These signals are then passed along the hearing nerve to the auditory cortex.” Housed in the brain, the auditory cortex interprets nerve impulses as sound. “This happens very fast so that both continuous and intermittent noise is heard.”
Our sense of hearing tends to deteriorate naturally with age, but when we are young, our ability to hear is an essential part of our development. Dr. Abeyratne points out that “hearing is the first special sense to develop in infants.” It allows the child to respond to his or her mother’s voice soon after birth, and later on listening becomes a crucial step in the acquisition of speech, with kids absorbing the way adults around them communicate. “In other words if an infant can’t hear, he or she won’t speak,” says Dr. Abeyratne, establishing that this critical period of development begins at birth and lasts till a child is about two years old. It’s why infants should be screened for hearing loss early on.
The loss of sound
When someone loses their ability to hear it could be for any number of reasons. “If it occurs in the outer ear, the ear canal, ear drum or ossicular chain, the mechanical transmission of vibrations are affected and it is called a conductive hearing loss,” he says. “When the hearing loss is due to inner ear, cochlear and hearing nerve and auditory cortex problems, this is termed a sensorineural hearing loss.” Both types can be congenital (present at birth) or appear only as a person grows older.
When it comes to conductive hearing loss, one of the most common causes of the condition has been dubbed ‘impacted wax.’ Everyone produces earwax. In the appropriate quantity it helps keep water out along with particles of dust and dirt. However, patients with impacted ears might find layers of wax have built up inside and are now putting pressure on the ear drum. They complain of bouts of dizziness, a sense of ‘fullness’ in their ears, compounded by hearing loss and irritability.
Hearing loss can also occur when an infection attacks the outer ear or the middle ear, leading to the swelling of the ear canal or the buildup of fluid behind the ear drum. Congenital malformations of the external ear, ear drum or ossicles have been associated with hearing loss but even more common are cases of trauma where ruptured ear drums adversely impact hearing.
In contrast, the most common cause of sensorineural hearing loss is actually aging. The delicate hair cells in corti in the cochlea are easily damaged by exposure to a very loud noise or even certain drugs. Since they do not regenerate, their loss is a serious blow.
Acute sensorineural hearing loss
The sudden loss of your hearing should always be treated as an emergency. Seeking treatment early can mean the difference between recovering and losing your hearing permanently – “statistically it has been proven that those patients that benefit from treatment for this emergency are those who come early to see an ENT specialist.”
“Usually a person who had good hearing may feel a numbness, a block or a popping sensation of the ear that leads to a hearing loss,” says Dr. Abeyratne, adding that it is typically in one ear. This loss can be immediate or play out over 72 hours, and many people experience bouts of dizziness as well. Both sensorineural problems and conductive problems might trigger such a loss, along with metabolic causes like diabetes, high cholesterol and even trauma such as a head injury.
Other problems include immunologic diseases such as Cogan’s syndrome, circulatory problems and neurologic causes such as multiple sclerosis. “Extremely loud noises also can cause this due to acoustic trauma,” says Dr. Abeyratne. “The danger is that usually the patient may not realize that he or she can’t hear and may ignore it till it is too late.”
Treatment
Treatment options are chosen on the basis of what causes the loss of hearing in the first place. “Infections such as viruses (mumps, rubella, measles) can be prevented by vaccination,” says Dr. Abeyratne. Your ENT surgeon will also need to eliminate the possibility that a drug you’ve been prescribed for another condition is the underlying cause and rule out the small possibility that a tumor or a vascular problem is responsible. Modern hearing aids and cochlear implants have been known to help patients cope with hearing loss.
In cases of sudden hearing loss, some patients will recover within days, others make take a week or more. For a small but significant percentage, the hearing loss gets worse over time. Treatment can include a course of antibiotics and steroids to boost the immune system. Some doctors recommend a diet low in salt.
It’s time to go to the doctor
How do you know if you have hearing loss? Check with your doctor if you:
- Have trouble hearing over the telephone
- Find it hard to follow conversations when two or more people are talking
- Often ask people to repeat what they are saying
- Need to turn up the TV volume so loud that others complain
- Have a problem hearing because of background noise
- Think that others seem to mumble
- Can’t understand when women and children speak to you
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