The definition of sudden loss of hearing is usually based on time course, severity, frequency spectrum and audiometric criteria. Abrupt and rapidly progressive loss is all covered under one definition. Awakening with loss of hearing, losses of hearing over a couple of days, high frequency hearing loss as well as distortions of speech perceptions have been defined as sudden hearing loss or adventitious hearing loss. The most commonly used criteria for qualifying for the diagnosis of adventitious hearing loss is sensorineural greater than 30 decibel more than three contiguous pure tone frequencies which occur within the period of 3 days.
What is Adventitious Hearing Loss?
Adventitious hearing loss or sudden sensorineural hearing loss which is commonly called as sudden deafness happens as a rapid and unexplained hearing loss generally inside one ear. It is supposed to be considered as a medical emergency. A person experiencing adventitious hearing loss should see a doctor immediately. Sometimes, people suffering with adventitious hearing loss put off visiting a doctor as they think that this loss of hearing is because of allergies, sinus infection, etc.
9 out of 10 people suffering from adventitious hearing loss lose hearing ability in just one ear. This loss of hearing is diagnosed by a hearing test. In case the test signifies a loss of 30 decibels in 3 of the connected frequencies, the loss of hearing is diagnosed as adventitious hearing loss or sudden sensorineural hearing loss. For instance, a loss of hearing of at least 30 decibels makes the conversational speech sound just like whisper.
A lot of people realise that they have this disease when they all of a sudden wake up in morning. Others notice it first while trying to use deafened ear like while using a phone. Still others realise it with a loud and alarming pop right before the hearing disappears. People who are suffering from sudden deafness feel dizziness, with a ringing sound in their ear.
Approximately, half the people suffering from adventitious hearing loss recover some of the hearing spontaneously within 1-2 weeks of the onset. 85% of the people who are treated by an otolaryngologist, recover from some of the hearing loss.
Experts estimate that this disease strikes 1 every 5000 persons every year. Actual number of cases of this disease every year may be a lot more as the condition is often undiagnosed. A lot of people recover quickly and do not seek medical assistance.
What Causes Adventitious Hearing Loss?
Just 10-15% of the patients who are diagnosed with adventitious hearing loss have identifiable cause. Some of the common causes of adventitious hearing loss include:
- Trauma like head injury
- Infectious diseases
- Ototoxic drugs which harm sensory cells of the inner ear
- Autoimmune diseases like Cogan's syndrome
- A tumour on nerve which connects the ears with the brain
- Neurologic disorders and diseases like multiple sclerosis
- Blood circulation issues
- Disorders of inner ear, like Meniere's disease.
How is Adventitious Hearing Loss Diagnosed?
For diagnosing adventitious hearing loss, a doctor would conduct hearing test known as pure-tone audiometry. This is a test which helps the doctor in determining whether the loss of hearing is caused due to sound not reaching the inner ear due to an obstruction like ear wax or fluid or due to sensorineural issues. The pure tone audiometry may even show range of the hearing which might have been lost.
In case you have been diagnosed with adventitious hearing loss, your doctor would probably conduct the other tests for trying to state the underlying cause for adventitious hearing loss. These kinds of tests may comprise of imaging, blood tests, balance tests, etc.
How is Adventitious Hearing Loss Treated?
A common treatment for adventitious hearing loss especially when the cause is not known is administration of corticosteroids. Steroids are also used for treating a number of disorders and generally work by prominently reducing inflammation, swelling and helping the human body fight illness. The steroids are generally prescribed in the form of pills. Recently, direct injection of the steroids behind eardrum in the mid ear known as intratympanic corticosteroid therapy is becoming popular. In the year 2011, a medical trial assisted by NIDCD proved that intratympanic steroids were quite efficient than the oral steroids but were not so effective in the patients. They remain as an option for the people who are not ok with oral steroids.
Additional treatment might be required in case the doctor discovers the real underlying cause of adventitious hearing loss. For instance, if adventitious hearing loss is caused due to an infection, then your doctor might prescribe some antibiotics. In case you are taking some drugs orally which are toxic for the ear, then your doctor might tell you to either switch to another drug or just stop it completely. In case, you are suffering from an autoimmune condition which causes the immune system to cause damage the inner part of the ear, then you might have to take some drugs for suppressing the immune system.
Since very little is known about causes of adventitious hearing loss, researchers are still studying about the changes in inner ear like disrupted flow of blood or inflammation which might contribute to loss of hearing. The researchers are even testing a lot of new ways of using imaging tests for diagnosing adventitious hearing loss and detecting the potential causes. Hence, one needs to consult a doctor as soon as they experience hearing loss.