Identification and Evaluation of Hearing Loss

CAUSES OF HEARING LOSS

There are many causes of hearing loss, including genetic conditions, complications at birth, exposure to infectious diseases, chronic ear infections, the use of particular drugs, exposure to excessive noise and aging.5 Hearing loss can be divided into congenital and acquired causes. Congenital hearing loss is present at birth while acquired causes can lead to hearing loss at any age.5

Congenital Causes

• Genetic, non-syndromic such as mutations in GJB2, GJB6 and TMPRSS3
• Genetic, syndromic such as Usher, Waardenburg and Pendred syndromes
• Birth asphyxia
• Low birth weight
• Maternal rubella, syphilis, cytomegalovirus (CMV) and other infections during pregnancy
• Severe jaundice in the neonatal period
• Use of particular drugs during pregnancy, such as aminoglycosides, cytotoxic drugs, antimalarial drugs and diuretics
• Cochlear malformations such as incomplete partition of the cochlea (Mondini malformation), common cavity, cochlear aplasia, cochlear hypoplasia and enlarged vestibular aqueduct (EVA)

Acquired Causes

• Aging (due to degeneration of sensory cells)
• Chronic ear infections
• Excessive noise, including occupational noise such as that from machinery and explosions
• Infectious diseases including meningitis, measles and mumps
• Injury to the head or ear
• Recreational exposure, such as using headphones at high volumes and for prolonged periods of time or regular attendance at concerts, nightclubs and sporting events in loud venues
• Use of certain medications, such as those used in treatment of neonatal infections, malaria, drug-resistant tuberculosis and cancers

IDENTIFICATION OF HEARING LOSS—ADULTS

It is important to perform routine hearing screenings so appropriate measures can be taken, including a referral to an audiologist, if needed. During routine physical exams, clinicians can visually examine both ears, ask about family history of hearing loss and noise exposure, educate patients about hearing protection, and recommend or provide additional hearing tests, if appropriate. While screening for hearing loss is good practice, studies indicate that 40% to 70% of primary care clinicians have not asked about or screened their patients for hearing loss.²⁰ The American Speech-Language-Hearing Association recommends that adults be screened at least every decade through age 50 and every three years thereafter for hearing loss.²⁰

Individuals who currently use hearing aids should have a yearly hearing test with their audiologist, as well. When their current hearing assistive devices fail to provide adequate hearing amplification, patients may show some signs.

• Symptoms of hearing loss in adults include:
• Avoiding some social settings or interactions
• Frequently asking others to speak more slowly, clearly and loudly
• Having difficulty understanding words, especially against background noise or in a crowd
• Having trouble hearing consonants
• Muffling speech and other sounds
• Preferring text messages to avoid phone calls
• Depending on closed captioning or needing to turn up the volume of the TV or radio
• Withdrawing from conversations or failing to respond when they cannot see who is speak

IDENTIFICATION OF HEARING LOSS—CHILDREN

Early detection and treatment of hearing loss is crucial to minimizing the impact of a child’s development and educational achievements.⁵ Infants should be screened for hearing loss in their first few days of life and identified by 3 months of age. Those identified as deaf or hard of hearing should be fitted with hearing aids and enrolled in early intervention by 6 months of age. The American Academy of Pediatrics (AAP) endorses hearing screening throughout infancy, early childhood, middle childhood and adolescence.²¹

Once identified as having hearing loss, children can benefit from the use of hearing devices, such as hearing aids, cochlear implants and other assistive devices. Children also benefit from speech therapy and aural (re)habilitation.⁵ If the parents of a child with hearing loss decide not to pursue hearing devices, the child can learn to communicate through cued speech, lip reading or sign language.⁵ Parents should be appropriately counseled regarding the risks and benefits to choosing one of these communication modalities.

• Symptoms of hearing loss in children include:
• Failing to respond to his/her name
• Having delayed, unclear or no speech
• Not following directions
• Not reacting to loud sounds
• Not turning to the source of a sound after 6 months of age
• Turning the volume up too high

METHODOLOGY FOR SCREENING

Hearing screenings are appropriate for any age, with most babies having a screening before they leave the hospital following delivery. Children get screenings at school or at the doctor’s office. Adults can go to their doctor’s office for a screening. These quick tests are simple and painless. The two common screening methods for babies are otoacoustic emissions (OAEs) and auditory brainstem response (ABR). For older children and adults, a pure-tone test is the most common screening.

Screening for hearing loss may begin with a general physical exam to identify possible causes of hearing loss, such as cerumen impaction or middle ear infection. A physical exam may also identify structural causes of hearing loss. Other tests that may be used to diagnosis hearing loss include:

• General screening tests—The whisper test can be performed, although its accuracy is limited.
• App-based hearing tests—Mobile apps have been developed so patients can screen themselves for moderate hearing loss using their smartphone or tablet.
• Tuning fork tests—A simple test done during a physical exam using a tuning fork can detect presence of hearing loss. The test may also reveal where in the ear the damage has occurred. Tuning fork tests, however, are not useful for characterizing severity of hearing loss.

METHODOLOGY FOR AUDIOMETRIC TESTING

If the patient does not pass a hearing screening, he/she should have an audiologic evaluation. An audiologist will ask questions about birth and medical history, ear infection, and hearing loss in the family and conduct full audiometric testing. Tests may include otoacoustic emissions (OAEs), auditory brainstem response (ABR), brainstem auditory evoked response (BAER), speech testing and/or behavioral audiometry evaluation.

During audiometric testing, the audiologist finds the patient’s threshold, or the softest sound the patient can hear 50% of the time, across the frequency range (250Hz to 8000Hz) by asking the patient to raise their hand or click a button when they hear the beep. This type of testing is completed using headphones or insert earphones and a bone conduction device to differentiate between conductive and sensorineural hearing loss.

The hearing loss is categorized by severity as follows:

Upon reviewing the test results and determining hearing loss, the audiologist discusses hearing solution options and recommendations with the patient.

REFERRAL CRITERIA FOR COCHLEAR IMPLANT CANDIDACY EVALUATION

Candidacy criteria for cochlear implantation is evolving as cochlear implant technology improves, and it can be difficult to know the appropriate time to refer a patient for a cochlear implant evaluation. If a patient currently wears hearing aids, the following screening questions may be asked during a physical exam to determine whether a referral for a cochlear implant candidacy evaluation may be warranted:

• Are you able to talk on the phone without visual cues (such as video calls or caption calling)?
• Are you able to understand TV programs without closed captioning?
• Are you able to effectively engage in conversations at large group gatherings, such as dinner parties?
• Do you feel that you obtain significant communication benefit from your current hearing aids?
• If the answer to at least two questions is no, the patient should be referred to an audiologist for a cochlear implant evaluation.

For referring professionals seeking more specific referral criteria, the following guidelines were recently published by leading professionals in the field of cochlear implants:

• Adults: Adults should be referred for a cochlear implant candidacy evaluation if they demonstrate the following: a better ear unaided monosyllabic word score of 60% correct or less and an unaided pure-tone average (average of thresholds at 500 Hz, 1000Hz and 2000 Hz, PTA) in their better ear of 60 dB HL or greater.²² This is referred to as the 60/60 guideline.
• Children: Children with hearing loss should be referred for a cochlear implant candidacy evaluation if their PTA exceeds 60 dB HL bilaterally.²³ To minimize speech and language delays due to auditory deprivation, implantation should be considered as soon as possible (prior to 9 months of age if hearing loss is congenital).
• It is important to note that these are guidelines for referral. Patients who do not meet these guidelines may benefit from cochlear implantation such as in cases of single-sided deafness and asymmetric hearing losses.

Management of Hearing Loss

Once hearing loss is identified, it can be at least partly remediated with hearing aids, auditory implants, and over-the-counter devices or accommodations. There are many hearing technology options for adults and children with hearing loss, which can aid communication and improve hearing-related quality of life.

EAR WAX REMOVAL

It is rare that cerumen impaction (ear wax occlusion) is severe enough to result in the degree of hearing loss required for cochlear implantation candidacy, but it is an important consideration for any hearing loss that may have occurred suddenly. The loss of hearing from cerumen impaction can be dramatic for a patient and any sudden onset of hearing loss is cause for immediate medical attention.

OVER-THE-COUNTER PRODUCTS

The Over-the-Counter (OTC) Hearing Aid Act of 2017 (HR 1652) has afforded adults with mild hearing loss access to wearable hearing technology without needing an audiologist consult. These OTC products look like Bluetooth headsets or earphones with some resembling traditional hearing aids. OTC hearing technology ranges in price from a couple hundred to a few thousand dollars. The devices are generally sold in pairs, though single ear devices are also available. These devices are appropriate for adults with minimal to mild typically flat hearing losses.

HEARING AIDS

For adults with more extensive or complex hearing loss and for all children, individualized hearing aids fitted by a licensed and certified audiologist are the most appropriate option. The hearing aids are programmable and adjusted specifically for the needs of the individual patient, shaping frequency and amplification characteristics to optimize audibility in various listening environments. Most hearing aids are now equipped with streaming capabilities via Bluetooth to allow seamless use of smartphones, TVs, computers and other digital technologies. Programmable hearing aids typically range from less than a thousand up to several thousand dollars per ear. For adults, some insurance plans offer hearing aid allowances to offset the cost of hearing aids, with benefits typically ranging from $1,000–$3,000 every three to five years. For children, most insurance plans and Medicaid offer partial or complete hearing aid coverage.

COCHLEAR IMPLANTS—ADULTS

Adults who have tried hearing aids and are still struggling with everyday communication are likely candidates for cochlear implants. Adult cochlear implant criteria have evolved dramatically over the past 40 years, such that adult implant candidates generally have moderate sloping to profound sensorineural hearing loss²⁴ and exhibit significant communication difficulties without the use of visual cues (e.g., lip reading, closed captioning).

Cochlear implants not only significantly improve hearing, speech perception, quality of life and relationships, but they also improve executive functioning in older adults. A study of the use of cochlear implants for moderating the effects of severe hearing loss on dementia and neurocognitive processing noted the possibility that decreased social isolation from hearing aid use may reduce the risk of cognitive decline.²⁵

COCHLEAR IMPLANTS—CHILDREN

Children with sensorineural hearing loss who have had limited to no functional benefit from hearing aids are likely candidates for cochlear implants. Audiological criteria for implantation in children are a congenital or acquired sensorineural hearing loss and limited to no functional benefit from hearing aids. Cochlear implants would be appropriate for children with pre- and post-lingual deafness only after they have had a sufficient trial with hearing aid amplification.

Because profound deafness in childhood affects the development of auditory speech perception, speech production and language skills, most children with severe to profound hearing loss do not develop oral communication skills with conventional hearing aids. Without adequate communication skills, children will be negatively impacted in their educational and employment opportunities. With early implantation, children have the opportunity to develop listening and spoken language that is comparable to their peers with typical hearing.

Patient Education

WHAT ARE COCHLEAR IMPLANTS AND HOW CAN THEY HELP?

A cochlear implant is a small, complex electronic device that can provide a sense of sound to a person who is profoundly deaf or severely hard-of-hearing.²⁶ The implant consists of an external device that sits behind the ear and an internal device that is implanted under the skin.²⁶ Although an implant does not restore normal hearing, it can provide a useful representation of sounds in the environment to help a person understand speech.

Under typical circumstances, patients can expect to detect sounds in the normal hearing range within a month of the activation of their external sound processor. Understanding speech will take time and practice. For post-lingually deafened (hearing loss occurring after speech skills are acquired) children and adults, the process of understanding speech slowly improves over six to 12 months. For pre-lingually deafened (hearing loss occurring before speech and language development) children, the process of understanding speech often takes years due to their age and developmental processes.

An implant consists of the following items to help achieve the goal of hearing.²⁶

• A microphone, which picks up sound from the environment
• A sound processor, which selects and arranges sounds picked up by the microphone
• A transmitter and receiver/stimulator, which receive signals from the sound processor and convert them into electronic impulses
• An electrode array, which is a series of electrodes directly inserted into the cochlea, that electrically stimulates the appropriate regions of the auditory nerve

HOW ARE COCHLEAR IMPLANTS DIFFERENT FROM HEARING AIDS?

Hearing aids and cochlear implants are very different in terms of how they help an individual hear. Hearing aids amplify sounds so they can be detected by damaged ears, while cochlear implants bypass damaged portions of the ear and directly stimulate the auditory nerve.²⁶ Signals generated by the implant are sent by way of the auditory nerve to the brain, which recognizes the signals as sound. Since hearing through a cochlear implant is different from normal hearing, it will take time for an implant recipient to learn to listen with the new electric stimulation after the procedure.²⁶

WHAT TO EXPECT FOR A COCHLEAR IMPLANT CANDIDACY EVALUATION

An audiologist will complete a comprehensive evaluation to determine if an individual is a candidate for cochlear implants. During examination of the ears, a visual inspection of the ear canal and ear drum is conducted using an otoscope. During this time, tympanometry is also performed to measure the middle ear pressure and mobility of the ear drum. Both of these procedures are necessary to rule out outer or middle ear abnormalities.

A standard hearing test is key to get a baseline of the patient’s hearing. For young children (less than 6 months) or children with additional disabilities for which a standard hearing testing may not be possible, other measurements are used to estimate hearing sensitivity. If a patient is using hearing aids, the audiologist will evaluate the hearing aids to ensure they are optimized for the individual’s hearing loss severity and configuration. A tiny probe microphone is placed in the ear canal to ensure that the hearing aids are providing the prescribed output level. If a patient’s hearing aids are not programmed optimally for their hearing loss, the audiologist will either reprogram the hearing aids or program clinic stock hearing aids to complete the evaluation.

The next portion of the evaluation focuses on aided speech recognition without visual cues. During this portion of the evaluation, the patient is instructed to listen to words and sentences spoken at a conversational rate and level and sentences spoken in background noise, then to repeat what they hear. Recorded and normalized speech stimuli are presented from a loudspeaker placed in front of the patient.

If, after a thorough exam, the audiologist determines that the patient is a candidate for a cochlear implant(s) based on the findings of the audiogram, aided speech recognition scores and reported communication difficulty, the patient will be referred to radiology for pre-operative CT and MRI scans to rule out findings that may preclude surgery or identify anatomical conditions that may have an impact on the surgical procedure.²⁷ After imaging studies are complete, the patient will be seen by an otolaryngologist (ear, nose and throat, or ENT) surgeon for a complete evaluation of the ears. The ENT surgeon will also review the imaging studies of the temporal bone from the CT and MRI scans to evaluate the cochlea and auditory nerve anatomy prior to surgery.

COCHLEAR IMPLANT SURGERY & ACTIVATION

Cochlear implant surgery is a quick, one- to two-hour, outpatient procedure with minimal downtime. The surgery is covered by most insurance plans, including Medicare and Medicaid; however, some state Medicaid programs, such as Tennessee, do not cover cochlear implantation for individuals over 21 years of age. The cochlear implant will be activated by the audiologist one to two weeks after the surgery is complete; it is at this appointment that the patient receives the external sound processor. After surgery, patients will need rehabilitation and training on how to properly use the cochlear implant and learn or relearn the sense of hearing,²⁶ and they will be followed closely by audiologists and speech therapists during this process. After the first year of implantation, adults follow up with their audiologist yearly. Children are followed more frequently, and weekly private speech therapy is often recommended to optimize listening and spoken language outcomes.

References & Contributors List

Editor’s note: The reference section is a work in progress using keyed footnotes and will remain so until the editorial is finalized. At that time, the footnotes will be compiled as endnote citations.

REFERENCES

¹James B, Poulsen G. The case for capitation. Harvard Business Review. July-August 2016. https://hbr.org/2016/07/the-case-for-capitation. Accessed April 24, 2020.

²Dieleman JL, Baral R, Birger M, et al. US spending on personal health care and public health, 1996-2013. JAMA. 2016;316(24):2627-2646. https://www.ncbi.nlm.nih.gov/pubmed/28027366. Accessed April 24, 2020.

³Buchman C, Gifford R, Haynes D, et al. Unilateral cochlear implants for severe, profound, or moderate sloping to profound bilateral sensorineural hearing loss. JAMA Otolaryngol Head Neck Surg. 2020;146(10):942. doi:10.1001/jamaoto.2020.0998.

⁴Holder J, Gifford R. Cochlear Implant Access: Are We Making Progress? Cochlear ProNews Blog. https://pronews.cochlearamericas.com/cochlear-implant-access-are-we-making-progress-holder-gifford/. Published 2018. Accessed February 9, 2021.

⁵World Health Organization. Deafness and Hearing Loss. https://www.who.int/news-room/fact-sheets/detail/deafness-and-hearing-loss. Accessed February 9, 2021.

⁶Holmes D. Lasker Foundation honours cochlear-implant pioneers. Lancet. 2013;382(9896):926. doi:10.1016/s0140-6736(13)61864-4.

⁷Wilson B, Dorman M. Cochlear implants: Current designs and future possibilities. The Journal of Rehab Res and Dev. 2008;45(5):695-730. doi:10.1682/jrrd.2007.10.0173.

⁸Livingston G, Sommerlad A, Orgeta V, et al. Dementia prevention, intervention, and care. Lancet. 2017;390(10113):2673-2734. doi:10.1016/S0140-6736(17)31363-6.

⁹Holder J, Reynolds S, Sunderhaus L, Gifford R. Current Profile of Adults Presenting for Preoperative Cochlear Implant Evaluation. Trends Hear. 2018;22:233121651875528. doi:10.1177/2331216518755288.

¹⁰Clark J. Uses and abuses of hearing loss classification. ASHA. 1981;23:493-500.

¹¹Centers for Disease Control and Prevention. Types of Hearing Loss. https://www.cdc.gov/ncbddd/hearingloss/types.html. Published 2020. Accessed February 22, 2021.

¹²Newman C, Weinstein B, Jacobson G, Hug G. The Hearing Handicap Inventory for Adults. Ear Hear. 1990;11(6):430-433. doi:10.1097/00003446-199012000-00004.

¹³Servidoni AB, Conterno LO. Hearing loss in the elderly: Is the Hearing Handicap Inventory for the Elderly—Screening version effective in diagnosis when compared to the audiometric test? Int Arch Otorhinolaryngol. 2018;22(1):1-8. doi:10.1055/s-0037-1601427.

¹⁴Gatehouse S, Noble W. The Speech, Spatial and Qualities of Hearing Scale (SSQ). Int J Audiol. 2004;43(2):85-99. doi:10.1080/14992020400050014.

¹⁵Noble W, Jensen N, Naylor G, Bhullar N, Akeroyd M. A short form of the Speech, Spatial and Qualities of Hearing Scale suitable for clinical use: The SSQ12. Int J Audiol. 2013;52(6):409-412. doi:10.3109/14992027.2013.781278.

¹⁶McRackan T, Hand B, Velozo C, Dubno J. Cochlear Implant Quality of Life (CIQOL): Development of a Profile Instrument (CIQOL-35 Profile) and a Global Measure (CIQOL-10 Global). Journal of Speech, Lang, and Hear Res. 2019;62(9):3554-3563. doi:10.1044/2019_jslhr-h-19-0142.

¹⁷Coninx F, Weichbold V, Tsiakpini L, et al. Validation of the LittlEARS(®) Auditory Questionnaire in children with normal hearing. Int J Pediatr Otorhin. 2009;73(12):1761-1768. doi:10.1016/j.ijporl.2009.09.036.

¹⁸Meinzen-Derr J, Wiley S, Creighton J, Choo, D. Auditory Skills Checklist: Clinical tool for monitoring functional auditory skill development in young children with cochlear implants. Annals Oto, Rhin, & Laryn. 2007;116(11):812-818. doi:10.1177/000348940711601104.

¹⁹Ching TY, Hill M. The Parents’ Evaluation of Aural/Oral Performance of Children (PEACH) scale: Normative data. J Am Acad Audiol. 2007;18(3):220-235. doi:10.3766/jaaa.18.3.4.

²⁰Carroll YI, Eichwald J, Scinicariello F, et al. Vital Signs: Noise-induced hearing loss among adults—United States 2011–2012. MMWR Morb Mortal Wkly Rep. 2017;66:139–144. doi: http://dx.doi.org/10.15585/mmwr.mm6605e3.

²¹American Academy of Audiology. Childhood Hearing Screening Guidelines. Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/hearingloss/documents/AAA_Childhood%20Hearing%20Guidelines_2011.pdf. Accessed February 10, 2021.

²²Zwolan T, Schvartz-Leyzac K, Terrence P. Development of a 60/60 guideline for referring adults for a traditional cochlear implant candidacy evaluation. Otol Neurotol. 2020;41(7):895-900. doi:10.1097/MAO.0000000000002664.

²³Leigh J, Dettman S, Dowell R. Evidence-based guidelines for recommending cochlear implantation for young children: Audiological criteria and optimizing age at implantation. Int J Audiol. 2016;55:S9-S18. doi:10.3109/14992027.2016.1157268.

²⁴Centers for Medicare & Medicaid Services. Cochlear Implantation. https://www.cms.gov/Medicare/Coverage/Coverage-with-Evidence-Development/Cochlear-Implantation–.Accessed February 11, 2021.

²⁵Sarant J, Harris D, Busby P, et al. The effect of hearing aid use on cognition in older adults: Can we delay decline or even improve cognitive function? J Clin Med. 2020;9(1):254. doi:10.3390/jcm9010254.

[Sarant]

²⁶National Institute of Deafness and Other Communication Disorders. Cochlear Implants. https://www.nidcd.nih.gov/health/cochlear-implants. Published 2017. Accessed February 24, 2021.

[NIDCD]

²⁷Widmann G, Dejaco D, Luger A, Schmutzhard J. Pre- and post-operative imaging of cochlear implants: A pictorial review. Insights Imaging. 2020;11(1). doi:10.1186/s13244-020-00902-6.