| | Features |
| Conductive hearing loss |
| Conditions affecting the outer ear |
| Obstruction (eg, by cerumen or by bony growths) | - Cerumen is the most common cause of outer ear obstruction.
- Exostoses are benign broad-based osseous lesions that usually present in adolescence or early adulthood. There is often a history of chronic cold water exposure. The lesions are often multiple and bilateral.
- Osteomas are benign solitary smooth-round osseous lesions occurring inside the bony ear canal. These lesions usually present in middle age but can occur in childhood.
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| Otitis externa | - Typically develops after local trauma to the ear canal or when impacted cerumen becomes contaminated by bacteria after swimming or showering.
- Hearing loss occurs if there is considerable accumulation of debris, edema, or inflammation in the ear canal.
- Symptoms include ear pain, pruritus, and discharge.
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| Congenital malformations (eg, microtia, stenosis or atresia of the external auditory canal) | |
| Conditions affecting middle ear |
| Infection (eg, acute otitis media and otitis media with effusion) | - Most common causes of conductive hearing loss in childhood.
- Hearing loss is usually mild to moderate (approximately 25 dB on average).
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| Tympanic membrane perforation | - Can be caused by barotrauma, ear infections, foreign body injury (eg, cotton-tipped applicator), temporal bone fractures, ear infections, or blast injury.
- The degree of conductive hearing loss depends upon the size and location of the perforation.
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| Trauma (eg, temporal bone fracture) | - Middle ear injury occurs in more than one-half of patients with temporal bone basilar skull fractures; injuries can also occur after direct blunt trauma to the external auditory canal (eg, hand blow to ear).
- Findings may include hemotympanum and otorrhea (bloody or clear).
- Hearing loss is often mixed (both conductive and SNHL).
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| Tumors (eg, cholesteatoma, otosclerosis) | - A cholesteatoma is an abnormal growth of squamous epithelium in the middle ear and mastoid. It may progressively enlarge to surround and destroy the ossicles. Suggestive findings include a white mass behind an intact tympanic membrane, a deep retraction pocket, or focal granulation on the surface of the tympanic membrane.
- Otosclerosis is an abnormality of bone remodeling that produces overgrowth of sclerotic bone, particularly on the footplate of the stapes. It is uncommon in childhood.
- Malignant tumors (eg, squamous cell carcinoma) and proliferative disorders (eg, Langerhans cell histiocytosis) are rare causes of conductive hearing loss in childhood.
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| Congenital malformations of the ossicles (eg, ossicular chain fixation) | |
| Sensorineural hearing loss (SNHL) |
| Congenital SNHL |
| Genetic hearing loss | |
| Nongenetic causes of congenital SNHL |
| Congenital infection (eg, CMV) | - Congenital CMV is a major cause of pediatric SNHL. Hearing loss can occur in infants with overtly symptomatic infection and in those who lack apparent symptoms. SNHL can be progressive or delayed in onset, and it can be either unilateral or bilateral.
- Other TORCH infections that can cause SNHL include congenital toxoplasmosis, rubella, syphilis, and Zika virus.
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| Inner ear dysplasias or malformations (eg, enlarged vestibular aqueduct) | - Hearing loss can range from mild to progressive to complete deafness.
- May be associated with vestibular problems (eg, poor balance or late walking).
- Diagnosis is made with high-resolution CT or MRI.
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| Perilymph fistula | - Leak of inner ear fluid through a defect in the otic capsule permitting communication between the middle ear and the inner ear.
- Uncommon cause of SNHL.
- Typical symptoms include fluctuating severe SNHL, dysequilibrium, and aural fullness.
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| Acquired SNHL |
| Prematurity | - Prematurity is an important risk factor for SNHL, though it is not a cause per se.
- Factors that contribute to increased risk of SNHL in preterm infants include perinatal complications, hyperbilirubinemia, ambient noise, and use of ototoxic drugs.
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| Hyperbilirubinemia | - The risk of hearing loss is greatest in neonates with hyperbilirubinemia above the threshold for exchange transfusion.
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| Infection (eg, bacterial meningitis) | - SNHL occurs early in the course of bacterial meningitis, with possible recovery or worsening during the first two weeks of illness.
- Follow-up hearing assessment is important.
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| Ototoxic drugs | - Examples of ototoxic drugs include aminoglycosides, high-dose loop diuretics, certain chemotherapeutic agents (eg, cisplatin), salicylates, and antimalarial drugs (eg, quinine and chloroquine).
- SNHL associated with many of these drugs is permanent.
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| Noise exposure | - Can occur over time with constant or repeated exposure to loud noise (eg, using a personal listening device at high volume for an extended period of the day) or following a short blast of very loud noise (eg, >150 dB).
- Initially presents as high-frequency hearing loss but can progress to involve more frequencies.
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| Trauma (eg, temporal bone fracture) | - Trauma to the temporal bone can cause SNHL or mixed hearing loss.
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| Tumor (eg, vestibular schwannoma) | - Vestibular schwannoma (also called acoustic neuroma) occurs most commonly in children with neurofibromatosis type 2.
- Symptoms and signs include tinnitus, disequilibrium, dizziness, headaches, facial hyperesthesia, facial muscular twitching, and facial paresis/paralysis.
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| Heavy metals | - Lead poisoning can cause high frequency SNHL.
- Cadmium, mercury, and arsenic also may have toxic effects on cochlear cells.
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| Central auditory disorders |
| Cortical deafness | - Associated with brain injury or disease. The abnormality may be due to global brain injury or lesions in areas involved in auditory neural processing, from the cochlear nucleus of the brainstem to the primary auditory complex in the temporal lobe of the brain.
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| Central auditory processing disorder | - Refers to inefficient and/or ineffective processing and utilization of auditory information by the central nervous system.
- Patients have normal hearing sensitivity, yet have difficulty interpreting sounds in complex situations (eg, speech or with background noise).
- The diagnosis cannot be made with audiologic testing alone and usually requires a battery of behavioral tests.
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