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Conductive Hearing Loss

Editor: Orlando De Jesus Updated: 8/23/2023 12:39:09 PM

Introduction

Hearing loss is often divided into three types: conductive, sensorineural, and mixed.[1] Conductive hearing loss encompasses a range of conditions. This is because a pathology anywhere from the pinna and the external acoustic meatus to the foot of the stapes bone can produce a conductive hearing loss (abnormal mechanical transmission of sound from the EAC to the cochlea).[2] Many anatomical structures in this area are susceptible to a wide range of pathologies.

Conductive hearing loss is prevalent and affects a wide demographic, from the very young to the elderly.[3] The causes can also range from the trivial otitis media with effusion in young children to potentially severe conditions such as an effusion caused by a nasopharyngeal tumor in adults. Thus, a thorough understanding of conductive hearing loss is paramount for all clinicians. Conductive hearing loss is a disease process frequently encountered by otolaryngologists, general practitioners, nurses, and audiologists.

Etiology

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Etiology

Conductive hearing loss can be produced by any defect in the pinna, external auditory canal, tympanic membrane, and ossicles, up to the footplate of the stapes. Problems with the external ear and auditory canal may be due to congenital abnormalities such as aural atresia, which results in the incomplete formation of the external ear. This anomaly occurs due to the maldevelopment of the first and second branchial arches and the first branchial cleft.[4] More commonly, problems arise at the external canal by obstruction from debris, wax, or foreign bodies. Perforation of the tympanic membrane can also cause a conductive hearing loss.[5] Perforation can be attributed to trauma using cotton swabs to clean the ear, barotrauma from deep water diving, or as a sequela of otitis media.

Pathologies in the middle ear resulting in a conductive hearing loss include acute otitis media and otitis media with effusion (commonly referred to as glue ear). Otitis media with effusion is the most common cause of acquired hearing loss in children.[6] In most cases, it is a transient issue, which often recovers spontaneously, and no further management other than monitoring is required. However, in some children, hearing loss can have disastrous consequences on speech and language development. Middle ear effusions in an adult should raise suspicion of a nasopharyngeal tumor (particularly a unilateral effusion or a refractory effusion) and should be investigated as such.[7] Another serious cause of conductive hearing loss is cholesteatomas. These occur due to the presence of squamous epithelium in the middle ear or other aerated areas within the temporal bones. Although they are not tumors, they can be locally destructive and therefore require surgical removal.[8] Restoration of hearing is a secondary objective behind the formation of a safe, dry ear.

A defect in the ossicles of the middle ear will also give a conductive hearing loss. This could be due to head trauma resulting in ossicle discontinuity, or it could be due to a disease process such as otosclerosis. Otosclerosis is an osseous dyscrasia within the temporal bone.[9] Spongy bone from the otic capsule gets replaced by sclerotic bone. This process predominantly affects the anterior oval window, resulting in calcification of the stapes or the annular ligament. Otosclerosis is twice as common in women and presents in early adulthood with a gradual onset of conductive hearing loss due to the stapes' fixation.

Epidemiology

Conductive hearing loss is common in younger patients due to conditions such as otitis media with effusion. A study on primary school children found the prevalence of hearing loss to be 15%, with 88.9% of those being conductive.[10] Another study with preschool children in a South African community showed that 19% had hearing loss, with 65% of those being conductive.[11] They found that 9% of children had impacted cerumen, causing a hearing loss in 19% of them. In a Canadian study in school children from kindergarten to grade 6, hearing loss was found in 19%, with 93% of those being conductive. They found perforations of the tympanic membrane in 37% if unilateral loss and 46% in the bilateral loss.[12]

In low-middle income countries, hearing loss secondary to otitis media can be as high as 26%.[13] Otosclerosis prevalence in the white population is 0.04% to 1% but increases to 5% in Asians, and is associated with bilateral hearing loss in up to 80% of cases.[14] In the elderly population, hearing loss is mostly attributed to presbycusis, which is sensorineural.[15]

History and Physical

A thorough history can point towards the cause of the hearing loss. When obtaining the child's pertinent history, it is essential to ask about speech and language development and whether the appropriate milestones have been reached. Whether the child had preceding or recurrent upper respiratory tract infections must be ascertained, as this may suggest an otitis media with effusion. A conductive hearing loss can manifest as inappropriate behavior or inattention in the classroom.[16] 

Other essential things in the history of children and adults include the onset of hearing loss, whether there was any trauma, and the presence of associated symptoms such as vertigo, otorrhoea, otalgia, and facial weakness. It would be prudent to ask about nasal discharge and weight loss in the older patient, indicating a postnasal space tumor. A child with a history of otitis media during the first two-three years of life are at risk for a mild-to-moderate conductive hearing loss affecting phonological production. They can have difficulty perceiving strident or high-frequency consonants, such as sibilants. During speech they typically fail to produce these consonants, since they do not perceive them. This failure of sound production is called stridency deletion.

It is important to ask about family history and birth history to exclude any familial syndromes. Otosclerosis has an autosomal dominant with an incomplete penetrance mode of inheritance. It usually presents in the third decade of life and is twice as common in women as men. It has a gradual onset, and the hearing loss is bilateral in 80% of cases.[17] The patient with otosclerosis may comment that their hearing is better with background noise (paracusis Willisii). This phenomenon can occur as well in other causes of conductive hearing loss.

A full otolaryngology examination is mandatory for patients with hearing loss. Both ears must be examined with an otoscope or microscope. The examiner can see an obstruction of the ear canal with cerumen, debris, or a foreign body. Stenosis of the canal, which may be congenital or the consequence of repeated infections, can be seen. The tympanic membranes must be visualized to exclude acute infections, effusions, perforations, hemotympanum, or the presence of a cholesteatoma. Approximately 90% of patients with otosclerosis have normal tympanic membranes, while 10% have a pink tinge called Schwartz’s sign.[18] If an adult is noted to have an effusion, then a flexible nasoendoscopy should be performed in the clinic to view the postnasal space.[19]

Weber and Rinne tuning fork tests are useful screening tests, which can be carried out in the clinic to see whether hearing loss is conductive or sensorineural.[20] They are better suited for unilateral hearing loss and when the hearing loss is not of the mixed type. Cases of bilateral hearing loss or mixed hearing losses are better assessed using pure tone audiometry rather than tuning fork tests. To perform the Weber test, a 512Hz tuning fork is struck on the clinician's knee or elbow, and the vibrating fork is placed in the vertex of the patient’s head of the midline of the forehead. A normal result is a tuning fork being heard equally in both ears. In a conductive hearing loss, the tuning fork will be heard louder in the affected ear. In a sensorineural hearing loss, the tuning fork will be heard louder in the unaffected ear. This is used in conjunction with the Rinne test, where again a vibrating 512Hz tuning fork is placed, this time on the mastoid process until the patient can no longer hear it, and then 1cm away from the external acoustic meatus. A normal result is when air conduction is heard better than bone conduction (paradoxically called Rinne positive). If bone conduction is superior to air conduction (Rinne negative), a conductive hearing loss is present.

Evaluation

Pure tone audiometry is the mainstay of investigations for hearing loss. It can confirm the presence of hearing loss, quantify the severity, and determine the nature of the hearing loss.[21] Headphones deliver sounds in varying loudness over 250 to 8000 Hz. The patient notifies the audiologist when they hear the sounds 50% of the time. This is a measure of the air conduction threshold and is recorded in decibels (dB). The bone conduction threshold is determined by placing a transducer on the mastoid process. An air-bone gap exists when bone conduction is superior to air conduction.[22] This is significant when the gap is over 10dB and marks a conductive hearing loss. Usually, an air-bone gap over 40dB indicates pathology within the ossicular chain rather than solely a tympanic membrane pathology. A Carhart notch is where there is a depression in bone conduction of around 10 to 15dB at 2kHz.[23] This is indicative of stapes fixation, as seen in otosclerosis.

Pure tone audiometry is suitable for patients over four years old. For younger children, there are alternative tests such as play and visual reinforcement audiometry. These are all subjective hearing tests. Acoustic impedance audiometry, also called tympanometry, provides some objective evidence for the examination. Tympanometry generates a graph of the tympanic membrane's compliance and gives useful information about the middle ear pressures.[24]

The work-up for a patient with a suspected cholesteatoma should include a computed tomographic scan of the petrous temporal bones. Brain and cervical magnetic resonance imaging with gadolinium may be subsequently recommended to exclude tumor pathologies of the posterior fossa, temporal bone, and neck/oropharynx areas.

Treatment / Management

The treatment of conductive hearing loss is dependent on the underlying condition. Any foreign body should be removed under direct visualization, with the aid of a microscope if required.[25] Wax and debris which is obstructing the ear canal should be amenable to micro-suction. Perforations of the tympanic membrane often heal independently and only require a clinic follow-up evaluation in 6-8 weeks to ensure total healing.[26] If the perforation has not sealed, then a myringoplasty may be necessary; however, the hearing effects are somewhat more unpredictable.

Otitis media with effusion usually resolves by itself and can just be monitored every three months. However, if persistent bilateral otitis media with effusion occurs over three months, and the hearing loss in the better ear is over 25-30dB, grommet insertion may be valuable.[27] Grommets enable ventilation of the middle ear to the external auditory canal, rather than ventilating to the nasopharynx via the Eustachian tubes. A myringotomy is performed, and any middle ear fluid is suctioned out before a grommet is placed in the anteroinferior quadrant. Adenoidectomy can also be performed if there is associated hearing loss with the effusions.[28] The most common complications of grommets are infections and rarely tympanosclerosis. Grommets are favored to tympanostomy tubes (T-tubes) as the latter have higher rates of complications.[29](A1)

Cholesteatomas require complete surgical excision. The two main approaches to a mastoidectomy are canal wall down, which involves an endaural or postaural incision, or canal wall up, which involves a postauricular incision.[30] Trauma resulting in ossicle discontinuity may require an ossiculoplasty. Management options for otosclerosis include conservative measures such as watchful waiting, hearing aids, and fluoride supplementation. Surgery may be indicated when the air-bone gap is over 20 dB and involve total/partial stapedectomy or stapedotomy.[31] Conductive hearing loss that is not amenable to medical or surgical management can be treated with hearing aids. There are various types: air conduction hearing aids, bone conduction hearing aids, and bone-anchored hearing aid.

Differential Diagnosis

The differential diagnosis for conductive hearing loss is extensive. A thorough history and examination, together with pure tone audiometry, will point towards the underlying cause. It is essential to confirm that the hearing loss is conductive rather than sensorineural, guiding subsequent investigations and management.

  • Defect in the pinna, external auditory canal, tympanic membrane, and ossicles
  • Aural atresia
  • External canal obstruction
  • Tympanic membrane perforation
  • Acute otitis media
  • Otitis media with effusion
  • Nasopharyngeal tumor
  • Cholesteatoma
  • Otosclerosis
  • Ossicle discontinuity after head trauma

Prognosis

Prognosis is very much dependent on the cause of the conductive hearing loss. Simple conditions such as wax impaction and otitis media with effusion have excellent outcomes.[32][33] Even when hearing loss is not reversible or amenable to medical or surgical management, hearing aids have a high satisfaction rate amongst patients.[34][35]

Complications

The following complications may be observed:

  • Conductive hearing loss in children can lead to disastrous speech and language delays and impact their education if not promptly diagnosed and treated.[36]
  • Cholesteatomas can have significant invasion and destruction of local structures.
  • Some conditions causing conductive hearing loss will produce a permanent hearing loss if untreated.

Consultations

Consultations from otolaryngologists, neuro otologist, and audiologist may be required.

Deterrence and Patient Education

Patients must realize that hearing loss, mainly if it is conductive, is treatable and should seek medical help if they noticed it. Hearing aids can be highly effective in cases when hearing loss is not treatable. Parents and teachers must be aware that misbehavior or inattention at school can be a sign of hearing loss, and prompt diagnosis can prevent speech and language delays. Patients should be instructed not to introduce sharp objects to clean the ear. The use of cotton swabs should be restricted to the most outer part of the external ear canal. Cotton swabs can push the wax deeper into the ear canal. In most cases, cleaning the ear canal should not be done with a cotton swab as the wax usually fall out on its own.

Enhancing Healthcare Team Outcomes

Hearing loss is a frequent problem affecting all ages. Careful diagnosis and treatment are required in many cases to prevent further complications. A multidisciplinary approach is necessary when managing conductive hearing loss, including otolaryngologists, audiologists, general practitioners, and specialty nurses. Pediatricians should closely follow patients with otitis media for recurrent episodes and problems in school learning and performance. Recommendations from all members of the team are obtained to achieve the best possible outcome for the patient. Using evidence-based information, the best results can be obtained.

References


[1]

Zahnert T. The differential diagnosis of hearing loss. Deutsches Arzteblatt international. 2011 Jun:108(25):433-43; quiz 444. doi: 10.3238/arztebl.2011.0433. Epub 2011 Jun 24     [PubMed PMID: 21776317]


[2]

Phan NT, McKenzie JL, Huang L, Whitfield B, Chang A. Diagnosis and management of hearing loss in elderly patients. Australian family physician. 2016 Jun:45(6):366-9     [PubMed PMID: 27622223]


[3]

Mamo SK, Reed NS, Price C, Occhipinti D, Pletnikova A, Lin FR, Oh ES. Hearing Loss Treatment in Older Adults With Cognitive Impairment: A Systematic Review. Journal of speech, language, and hearing research : JSLHR. 2018 Oct 26:61(10):2589-2603. doi: 10.1044/2018_JSLHR-H-18-0077. Epub     [PubMed PMID: 30304320]

Level 1 (high-level) evidence

[4]

Abdel-Aziz M. Congenital aural atresia. The Journal of craniofacial surgery. 2013 Jul:24(4):e418-22. doi: 10.1097/SCS.0b013e3182942d11. Epub     [PubMed PMID: 23851888]


[5]

Sogebi OA, Oyewole EA, Manifah TO, Ogunbanwo O. Hearing dynamics in patients with traumatic tympanic membrane perforation. Journal of the West African College of Surgeons. 2017 Apr-Jun:7(2):15-30     [PubMed PMID: 29951463]


[6]

Coleman A, Cervin A. Probiotics in the treatment of otitis media. The past, the present and the future. International journal of pediatric otorhinolaryngology. 2019 Jan:116():135-140. doi: 10.1016/j.ijporl.2018.10.023. Epub 2018 Oct 19     [PubMed PMID: 30554684]


[7]

Mills R, Hathorn I. Aetiology and pathology of otitis media with effusion in adult life. The Journal of laryngology and otology. 2016 May:130(5):418-24. doi: 10.1017/S0022215116000943. Epub 2016 Mar 15     [PubMed PMID: 26976514]


[8]

Kuo CL, Shiao AS, Yung M, Sakagami M, Sudhoff H, Wang CH, Hsu CH, Lien CF. Updates and knowledge gaps in cholesteatoma research. BioMed research international. 2015:2015():854024. doi: 10.1155/2015/854024. Epub 2015 Mar 18     [PubMed PMID: 25866816]


[9]

Quesnel AM, Ishai R, McKenna MJ. Otosclerosis: Temporal Bone Pathology. Otolaryngologic clinics of North America. 2018 Apr:51(2):291-303. doi: 10.1016/j.otc.2017.11.001. Epub 2018 Feb 3     [PubMed PMID: 29397947]


[10]

Khairi Md Daud M, Noor RM, Rahman NA, Sidek DS, Mohamad A. The effect of mild hearing loss on academic performance in primary school children. International journal of pediatric otorhinolaryngology. 2010 Jan:74(1):67-70. doi: 10.1016/j.ijporl.2009.10.013. Epub 2009 Nov 12     [PubMed PMID: 19913305]

Level 2 (mid-level) evidence

[11]

Yousuf Hussein S, Swanepoel W, Mahomed-Asmail F, de Jager LB. Hearing loss in preschool children from a low income South African community. International journal of pediatric otorhinolaryngology. 2018 Dec:115():145-148. doi: 10.1016/j.ijporl.2018.09.032. Epub 2018 Oct 3     [PubMed PMID: 30368375]


[12]

Fitzpatrick EM, McCurdy L, Whittingham J, Rourke R, Nassrallah F, Grandpierre V, Momoli F, Bijelic V. Hearing loss prevalence and hearing health among school-aged children in the Canadian Arctic. International journal of audiology. 2021 Jul:60(7):521-531. doi: 10.1080/14992027.2020.1731616. Epub 2020 Mar 17     [PubMed PMID: 32180475]


[13]

Leach AJ, Homøe P, Chidziva C, Gunasekera H, Kong K, Bhutta MF, Jensen R, Tamir SO, Das SK, Morris P. Panel 6: Otitis media and associated hearing loss among disadvantaged populations and low to middle-income countries. International journal of pediatric otorhinolaryngology. 2020 Mar:130 Suppl 1(Suppl 1):109857. doi: 10.1016/j.ijporl.2019.109857. Epub 2020 Jan 21     [PubMed PMID: 32057518]


[14]

Markou K, Goudakos J. An overview of the etiology of otosclerosis. European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery. 2009 Jan:266(1):25-35. doi: 10.1007/s00405-008-0790-x. Epub 2008 Aug 13     [PubMed PMID: 18704474]

Level 3 (low-level) evidence

[15]

Yamasoba T, Lin FR, Someya S, Kashio A, Sakamoto T, Kondo K. Current concepts in age-related hearing loss: epidemiology and mechanistic pathways. Hearing research. 2013 Sep:303():30-8. doi: 10.1016/j.heares.2013.01.021. Epub 2013 Feb 16     [PubMed PMID: 23422312]

Level 3 (low-level) evidence

[16]

Venekamp RP, Burton MJ, van Dongen TM, van der Heijden GJ, van Zon A, Schilder AG. Antibiotics for otitis media with effusion in children. The Cochrane database of systematic reviews. 2016 Jun 12:2016(6):CD009163. doi: 10.1002/14651858.CD009163.pub3. Epub 2016 Jun 12     [PubMed PMID: 27290722]

Level 1 (high-level) evidence

[17]

Crompton M, Cadge BA, Ziff JL, Mowat AJ, Nash R, Lavy JA, Powell HRF, Aldren CP, Saeed SR, Dawson SJ. The Epidemiology of Otosclerosis in a British Cohort. Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology. 2019 Jan:40(1):22-30. doi: 10.1097/MAO.0000000000002047. Epub     [PubMed PMID: 30540696]


[18]

Salomone R, Riskalla PE, Vicente Ade O, Boccalini MC, Chaves AG, Lopes R, Felin Filho GB. Pediatric otosclerosis: case report and literature review. Brazilian journal of otorhinolaryngology. 2008 Mar-Apr:74(2):303-6     [PubMed PMID: 18568213]

Level 3 (low-level) evidence

[19]

Cunniffe HA, Gona AK, Phillips JS. Should adults with isolated serous otitis media be undergoing routine biopsies of the post-nasal space? The Journal of laryngology and otology. 2020 Sep 10:():1-3. doi: 10.1017/S0022215120001887. Epub 2020 Sep 10     [PubMed PMID: 32907646]


[20]

Bayoumy AB, de Ru JA. Sudden deafness and tuning fork tests: towards optimal utilisation. Practical neurology. 2020 Feb:20(1):66-68. doi: 10.1136/practneurol-2019-002350. Epub 2019 Aug 23     [PubMed PMID: 31444233]


[21]

Musiek FE, Shinn J, Chermak GD, Bamiou DE. Perspectives on the Pure-Tone Audiogram. Journal of the American Academy of Audiology. 2017 Jul/Aug:28(7):655-671. doi: 10.3766/jaaa.16061. Epub     [PubMed PMID: 28722648]

Level 3 (low-level) evidence

[22]

Wiatr M, Wiatr A, Składzień J, Stręk P. Determinants of Change in Air-Bone Gap and Bone Conduction in Patients Operated on for Chronic Otitis Media. Medical science monitor : international medical journal of experimental and clinical research. 2015 Aug 11:21():2345-51. doi: 10.12659/MSM.894087. Epub 2015 Aug 11     [PubMed PMID: 26259623]


[23]

Wiatr A, Składzień J, Strek P, Wiatr M. Carhart Notch-A Prognostic Factor in Surgery for Otosclerosis. Ear, nose, & throat journal. 2021 May:100(4):NP193-NP197. doi: 10.1177/0145561319864571. Epub 2019 Sep 26     [PubMed PMID: 31558062]


[24]

Parlea E, Georgescu M, Calarasu R. Tympanometry as a predictor factor in the evolution of otitis media with effusion. Journal of medicine and life. 2012 Dec 15:5(4):452-4     [PubMed PMID: 23346249]


[25]

Grigg S, Grigg C. Removal of ear, nose and throat foreign bodies: A review. Australian journal of general practice. 2018 Oct:47(10):682-685. doi: 10.31128/AJGP-02-18-4503. Epub     [PubMed PMID: 31195771]


[26]

Sogebi OA, Oyewole EA, Mabifah TO. Traumatic tympanic membrane perforations: characteristics and factors affecting outcome. Ghana medical journal. 2018 Mar:52(1):34-40. doi: 10.4314/gmj.v52i1.7. Epub     [PubMed PMID: 30013259]


[27]

Rovers MM, Black N, Browning GG, Maw R, Zielhuis GA, Haggard MP. Grommets in otitis media with effusion: an individual patient data meta-analysis. Archives of disease in childhood. 2005 May:90(5):480-5     [PubMed PMID: 15851429]

Level 1 (high-level) evidence

[28]

Gates GA, Avery CA, Prihoda TJ, Cooper JC Jr. Effectiveness of adenoidectomy and tympanostomy tubes in the treatment of chronic otitis media with effusion. The New England journal of medicine. 1987 Dec 3:317(23):1444-51     [PubMed PMID: 3683478]

Level 1 (high-level) evidence

[29]

Kay DJ, Nelson M, Rosenfeld RM. Meta-analysis of tympanostomy tube sequelae. Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery. 2001 Apr:124(4):374-80     [PubMed PMID: 11283489]

Level 2 (mid-level) evidence

[30]

Karamert R, Eravcı FC, Cebeci S, Düzlü M, Zorlu ME, Gülhan N, Tutar H, Uğur MB, İriz A, Bayazıt YA. Canal wall down versus canal wall up surgeries in the treatment of middle ear cholesteatoma. Turkish journal of medical sciences. 2019 Oct 24:49(5):1426-1432. doi: 10.3906/sag-1904-109. Epub 2019 Oct 24     [PubMed PMID: 31651106]


[31]

Cheng HCS, Agrawal SK, Parnes LS. Stapedectomy Versus Stapedotomy. Otolaryngologic clinics of North America. 2018 Apr:51(2):375-392. doi: 10.1016/j.otc.2017.11.008. Epub 2018 Feb 3     [PubMed PMID: 29397948]


[32]

Wright T. Ear wax. BMJ clinical evidence. 2015 Mar 4:2015():. pii: 0504. Epub 2015 Mar 4     [PubMed PMID: 25738938]

Level 1 (high-level) evidence

[33]

Atkinson H, Wallis S, Coatesworth AP. Otitis media with effusion. Postgraduate medicine. 2015 May:127(4):381-5. doi: 10.1080/00325481.2015.1028317. Epub     [PubMed PMID: 25913597]


[34]

Kozlowski L, Ribas A, Almeida G, Luz I. Satisfaction of Elderly Hearing Aid Users. International archives of otorhinolaryngology. 2017 Jan:21(1):92-96. doi: 10.1055/s-0036-1579744. Epub 2016 Mar 9     [PubMed PMID: 28050214]


[35]

Ferguson MA, Kitterick PT, Chong LY, Edmondson-Jones M, Barker F, Hoare DJ. Hearing aids for mild to moderate hearing loss in adults. The Cochrane database of systematic reviews. 2017 Sep 25:9(9):CD012023. doi: 10.1002/14651858.CD012023.pub2. Epub 2017 Sep 25     [PubMed PMID: 28944461]

Level 1 (high-level) evidence

[36]

Tomblin JB, Oleson JJ, Ambrose SE, Walker E, Moeller MP. The influence of hearing aids on the speech and language development of children with hearing loss. JAMA otolaryngology-- head & neck surgery. 2014 May:140(5):403-9. doi: 10.1001/jamaoto.2014.267. Epub     [PubMed PMID: 24700303]

Level 2 (mid-level) evidence