We have all heard that music soothes the soul or calms the mind, but how does it do that? More and more we are finding that learning is easier and with better recall when it is put to music. Think of how many songs you can remember the lyrics for even though it may have been years since you learned or sang them, but recalling what you ate for dinner a week ago may be next to impossible.

Hearing is one of the five senses that as it becomes diminished the importance of correcting it is overlooked with people relying on visual cues such as lip reading to help them with communication often saying that it is not "bad enough yet."  While lip reading and asking others to repeat what has been said may be reasonable coping strategies, they do not compensate for the general brain stimulation that actually hearing provides. Simply put, hearing anything – sounds, voices and noises – stimulates the brain immensely, first converting the sounds into electrical energy, which then trigger multiple areas in the brain recalling past events and sounds, storing or learning the new sounds and as well connecting with another area of the brain to create a response that may be verbal, physical and/or emotional. This rich network of neurons connecting to interpret sounds, keeps the brain’s neuronal connections alive and vibrant.

How common is hearing loss?

The 2019 census estimates that there are about 331 million Americans with about 48 million having some form of hearing loss. Hearing loss is a common chronic public health problem, but if left untreated can have effects on mental, social, physical and financial health. It is estimated that fewer than 30 percent of adults 70 years and older who could benefit from hearing aids actually use them according to the National Institute of Deafness and other Communication Disorders. The incidence of neonatal hearing loss is 1.1 per 1,000 infant births in the U.S. and there is a prevalence of 3.1 percent amongst children and adolescents which makes hearing loss the most common sensory disorder in the U.S.  In 2007 the Joint Commission on Infant Hearing started to promote universal screening for early detection and intervention with the goal being to screen all infants for hearing loss prior to 1 month of age. For those who do not pass the initial screen, they should have a comprehensive audiologic evaluation by age 3 months with the goal being intervention for their hearing loss by 6 months of age.

Types of hearing loss

Congenital hearing loss is a type of hearing loss that is present at birth or develops shortly thereafter. It can be familial or spontaneous and either may be associated with a syndrome. Infections such as rubella, CMV and herpes simplex viral infection increase the risk for hearing loss.

Acquired hearing loss is a type of hearing loss that is not present at birth but is noted later in life. Common causes of acquired hearing loss are noise exposure e.g. to gunfire noises, loud music, aging, traumatic brain injuries with temporal bone fractures, neurodegenerative disorders e.g. multiple sclerosis and chronic diseases such as diabetes.

Both congenital and acquired hearing loss can be divided into conductive, sensorineural, or mixed hearing loss.

Conductive hearing loss (CHL) is due to problems with the ear canal, eardrum, or middle ear space and or the bones of hearing i.e. ossicles (the malleus, incus and stapes). Common examples of conductive loss cerumen impaction, eardrum perforation for example that can occur during diving or accidentally with use of a cotton swab piercing the eardrum. Middle ear space problems such as fluid in the middle ear space can cause significant hearing loss especially in children and lead to speech delay and as well behavioral issues. Ear tubes are the most common surgical procedure performed in the pediatric population and leads to reversal of the hearing loss with removal of the middle ear fluid.

At times, the bones of hearing or ossicles become calcified into place causing a condition known as otosclerosis which is reversed with surgery to restore mobility of the bones. This surgery stapedectomy is done awake and leads to immediate improvement in the hearing.

Sensorineural hearing loss (SNHL) is due to problems of the inner ear or cochlea and is also known as nerve related hearing loss. This is the most common type of loss and is often associated with aging. Other causes of hearing loss include exposure to loud noises, head trauma, viral disease or other illnesses, autoimmune disease, family history, autoimmune ear disorders, Ménière's disease, brain tumors on the nerve of hearing acoustic neuroma or schwannomas.

Tinnitus, which is noise in the ear or head that is audible only to person affected. Tinnitus may be of various qualities such as ringing, humming, bells, roaring, chickadees, etc. It is one of the body’s way of communicating that the ear has received too much insult or noise exposure. Medications including over-the-counter medications such as aspirin and ibuprofen, diet especially high salt diet, vitamin deficiencies, caffeine, sleep deprivation and infections can all cause the onset of tinnitus. Treating any underlying hearing loss generally improves and/or resolve the tinnitus. If the tinnitus is of sudden onset without noise exposure, involves only one ear/unilateral, or is pulsatile where it sounds like your heartbeat, it is considered a relative medical emergency and should be evaluated by an ear nose and throat specialist as soon as possible.

Testing

A hearing test or audiogram is performed in a sound proof booth ideally to eliminate other noises from distracting the person being tested so that the results are more accurate. During the tests the patient is asked to raise their hand or with body movements confirm when they first hear the sound. Testing such as auditory brainstem response (ABR) or otoacoustic emission (OAE) tests are also used to evaluate hearing and do not require the patient to respond and therefore babies, persons with disabilities or who are unwilling or unable to respond, can be reliably tested.  

Treatment for sensorineural hearing loss

Sudden sensorineural hearing loss occurs when someone awakens or suddenly during the daytime feels as though they are not able to hear on one side or the ear feels dead or clogged and on testing one  ear is with much less hearing and word understanding compared to the other. While this can be of viral or infectious etiology, it is often treated with combination of corticosteroids and treatment for any obvious infection. Often an MRI scan of the brain and internal ear canals is also ordered to evaluate for the possibility retrocochlear pathology such as growths on the nerve of hearing and balance complex.

Hearing loss associated with Ménière's disease is treated with hearing aids if the loss is present even when the other symptoms of Ménière's has resolved. Ménière's disease symptoms can be any combination of fullness in the ears, tinnitus, low-frequency hearing loss and dizziness or vertigo. The symptoms typically involve one ear more than the other and lasts for hours to days with spontaneous resolution and recurrence at sporadic intervals. Ménière's disease is generally managed with low-salt diet, corticosteroids and diuretic. At times surgery on the endolymphatic sac or parts of the inner ear may be needed if there is chronic vertigo.

Thankfully most often hearing loss treatment is amplification with hearing aids and or cochlear implants depending on the severity of the loss and the patient's benefit from conventional hearing aids.

Mixed hearing loss

Mixed hearing loss is caused by a combination of hearing loss in the middle ear space and nerve damage in the inner ear. Depending on the severity of the conductive component of the loss, mixed hearing loss is treated with a combination of surgery to correct the conductive component and hearing aids to correct the sensorineural or nerve portion of the loss. If the conductive component is relatively small then just hearing aids are used.

Hearing aids come in various shapes and styles and are selected by your audiologist for hearing instrument dispenser based on the type of hearing loss you have, your desires i.e., what features you want on your hearing aids such as being able to locate them with they are lost or amount of programming and price range.  The major manufactures of hearing aids are Starkey, Phonak, Oticon, Widex, and Resound.

Impact of hearing loss

The prevalence of dementia in the general public is increasing and projected to double every 20 years estimating that by the year 2050 nearly 1 in 85 persons will be affected worldwide. Dementia is not only devastating for the affected individual but poses a significant burden on the families, society and public safety. Interventions to prevent and cure dementia are therefore crucial to develop. Many studies have looked at the link between hearing loss and dementia but prior to 2011 the hypothesis had not been investigated prospectively. Frank Lin and his colleagues set out with the objective to determine if hearing loss is associated with incident all –cause dementia and Alzheimer's disease. They looked at 639 participants (age 36 to 90 years) of the Baltimore Longitudinal Study of Aging who had audiometric testing and were dementia free 1990- 1994. They defined hearing loss for 0.5, 1, 2, and 4 kHz as normal being less than 25 dB with 455 participants, mild hearing loss 25-40 dB (125 participants), moderate hearing loss 41-70 dB (53 participants), severe hearing loss greater than 70 dB (six participants). On average, they followed the participants for 12 years with the findings of 58 cases of incident all cause dementia with 37 of these being Alzheimer's disease. The risk of dementia increased log linearly with severity of baseline hearing loss. When compared to individuals who had normal hearing the hazard ratio for development of dementia was 1.89 for mild hearing loss, 3.04 moderate hearing loss and 4.94 for severe hearing loss. The greater hearing loss present at baseline, the greater the likelihood of that participant having dementia.  They concluded that hearing loss is independently associated with dementia.  

The question then becomes was the hearing loss a marker for dementia or an actual modifiable risk factor for dementia?

While about 26.7 million adults above the age of 50 have hearing impairment, only about 14 percent or 1 and 7 actually have pursued any treatment for it according to researchers at John Hopkins. A recent study, however, published in the Journal of the American Geriatric Society showed that wearing hearing aids improved memory capacity in impaired adults by 75 percent.  Drs. Asri Maharani and Piers Dawes, researchers in neuroscience and experimental psychologist and at the University of Manchester in the U.K. conducted a longitudinal study using data from the Health and Retirement Survey, an ongoing study sponsored by the National Institute on Aging. They analyzed 18 years’ worth of memory related data. There were 2,040 participants enrolled from 1996-2012. At the start of the study each participant was 50 years or older with no dementia or hearing aids. During the course of follow-up over the years, the rate of memory loss prior to adapting hearing aids was compared to that after adopting hearing aids. In both studies researchers performed a battery of face-to-face tests with the participants every two years. One memory test asked participants to recall 10 words immediately and then again after performing other cognitive tasks. The rate of memory decline slowed by up to 75 percent with the adoption of hearing aids. These results are particularly important because it was based on the general population and followed the same people over 18 years as opposed to comparing a group with no hearing loss to a different group with hearing loss.  

A similar study performed by the same researchers was done assessing cognitive improvement in patient who underwent cataract surgery using 2,068 individuals who had undergone cataract surgery between 2002 and 2014.  They were compared with 3,636 individuals with no cataract surgery. Overall findings was for 50 percent decrease in rate of cognitive decline after cataract surgery. Participants were in the English Longitudinal Study of Ageing, which is carried out similar to the U.S. Health and Retirement Survey. Lesson to be learned is that hearing and visual health are important to brain health.  

The two most  popular theories as to why hearing aid use may slow cognitive decline are the cascade hypothesis: In which hearing aids may reduce depression, promote social engagement, greater physical activity or self-confidence all of which improve cognitive function.

The other theory or mechanism is related to hearing aids decreasing sensory deprivation of the brain and slowing atrophy of the whole brain in particular the right temporal lobe. This is particularly meaningful given that the results of the Baltimore Longitudinal Study of Aging showing that participates with hearing loss had accelerated brain atrophy.

Take-home messages is that hearing aids help you to continue doing the things you want to do longer and keep you more socially engaged and independent. In particular during the month of May get your hearing tested.

Dr. Inell C. Rosario is an ear, nose, throat specialist (ENT) with Andros ENT and Sleep Center. For more information, or to schedule a free screening hearing test call (651) 888-7800.

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