{
 "topic": "Hearing Loss",
 "slug": "hearing-loss",
 "category_id": 15913,
 "summary": "Classification, screening, and evaluation of conductive and sensorineural hearing loss in children, including why universal newborn screening replaced risk-based screening.",
 "written_by": "claude-sonnet",
 "references": [
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 "short": [
  {
   "title": "In short",
   "content": "- Two primary types: conductive and sensorineural hearing loss (SNHL); auditory neuropathy spectrum disorder (ANSD) is a third, distinct type seen in at-risk children.\n- Severity grading: mild 26\u201340 dB, moderate 40\u201370 dB, severe 71\u201390 dB, profound >90 dB loss.\n- Congenital hearing loss is roughly 50% genetic, 50% acquired; of genetic cases, about 80% are autosomal recessive and two-thirds are nonsyndromic.\n- Newborn hearing screening uses otoacoustic emissions (OAE) and/or auditory brainstem response (ABR); ABR (but not OAE) can identify auditory neuropathy.\n- Universal newborn screening is now standard because risk factors (prematurity, persistent pulmonary hypertension, hyperbilirubinemia, mechanical ventilation/ECMO, congenital infection, meningitis, family history) are present in only about half of infants who turn out to have hearing impairment.\n- Overall prevalence of congenital hearing loss is about 1\u20133 per 1000 births.\n- Once a child can cooperate (typically by age 4), pure tone audiometry with air and bone conduction is the preferred test.\n- Otitis media is the most common acquired cause of conductive hearing loss in childhood: acute otitis media typically causes 15\u201340 dB loss (average ~27 dB with AOM or OME); permanent sensorineural loss can follow spread of infection through the round window or suppurative complications (labyrinthitis, meningitis).\n- The critical period for speech and language development is birth to 3 years \u2014 early identification and intervention prevent many of the downstream language, academic, and social consequences."
  }
 ],
 "long": [
  {
   "title": "Definition",
   "content": "Hearing loss in children is classified by the location of dysfunction along the auditory pathway (conductive, sensorineural, or mixed), with auditory neuropathy spectrum disorder (ANSD) recognized as a distinct third category of particular concern in at-risk infants. It is further described by timing (congenital vs. late-onset/acquired) and by severity: mild (26\u201340 dB loss), moderate (40\u201370 dB), severe (71\u201390 dB), and profound (>90 dB). Conductive hearing loss arises from any pathology interfering with sound conduction through the ear canal, tympanic membrane, or ossicles. Sensorineural hearing loss arises from pathology in the cochlea, auditory nerve, or central auditory pathway. Loss may be unilateral or bilateral, and either can cause significant childhood disability."
  },
  {
   "title": "Etiology",
   "content": "Congenital hearing loss is roughly half genetic and half acquired. Among genetic cases, about 80% are inherited as autosomal recessive traits, and roughly two-thirds occur without an associated syndrome (nonsyndromic); the remainder are syndromic, X-linked, autosomal dominant, or mitochondrial. Genetics consultation is valuable since it can identify a specific diagnosis, prognosis, and associated risks, and some genetic causes of hearing impairment do not manifest until later in childhood. Acquired causes recognized as neonatal risk factors include prematurity, persistent pulmonary hypertension, hyperbilirubinemia, need for mechanical ventilation or ECMO, congenital infection, and meningitis; a family history of hearing impairment is also a risk factor. Later in childhood, otitis media with effusion, tympanic membrane perforation, tympanosclerosis, and cholesteatoma are common acquired causes of conductive loss, while noise exposure (recreational vehicles, music, power tools, gunfire, firecrackers) is the leading modifiable environmental cause of acquired sensorineural loss, first producing a temporary threshold shift that can progress to permanent noise-induced hearing loss (NIHL) with repeated exposure."
  },
  {
   "title": "Clinical features",
   "content": "Because roughly half of infants who develop hearing impairment have no identifiable risk factor, hearing loss can be clinically silent in infancy and is instead detected by screening. In older children, parents may raise concerns about hearing acuity, or the child may present with speech and language delay, poor academic performance, or behavioral/social difficulties, since the birth-to-3-year window is the most critical period for speech and language development. In the context of acute otitis media or otitis media with effusion, conductive hearing loss is the most common complication; it is usually mild-to-moderate (15\u201340 dB, average ~27 dB) but can occasionally reflect reversible or permanent sensorineural involvement."
  },
  {
   "title": "Diagnostics",
   "content": "Universal newborn hearing screening has replaced screening limited to high-risk infants, since risk factors identify only about half of affected infants. The two screening methods are otoacoustic emissions (OAE) and auditory brainstem response (ABR); ABR is preferred when auditory neuropathy is a concern, since OAE can be normal in that condition. Once a child is old enough to cooperate \u2014 typically by around age 4 \u2014 pure tone audiometry with both air and bone conduction becomes the preferred test and can distinguish conductive from sensorineural components. Hearing testing should be pursued whenever language delay, learning problems, or hearing loss is suspected clinically, including after episodes of otitis media."
  },
  {
   "title": "Complications",
   "content": "Untreated hearing loss of any degree, unilateral or bilateral, can compromise speech and language development, academic performance, and social-emotional development. In acute otitis media, permanent sensorineural hearing loss can result from spread of infection or inflammatory products through the round window membrane into the labyrinth, from a perilymphatic fistula at the oval or round window, or from suppurative complications such as labyrinthitis or meningitis; reversible sensorineural loss during otitis media is attributed to increased tension and stiffness of the round window membrane. Hearing loss is now the third most common chronic physical condition in the United States, roughly twice as common as diabetes or cancer, underscoring how much of the burden is acquired and potentially preventable (e.g., noise-induced loss)."
  },
  {
   "title": "Prevention",
   "content": "Early identification through universal newborn screening allows early intervention, which has been shown to prevent many of the adverse language, academic, and social consequences of childhood hearing loss. For noise-induced hearing loss, avoiding sustained exposure to loud continuous noise (music, recreational vehicles, power tools) and brief high-intensity sounds (gunfire, firecrackers) prevents the temporary threshold shifts that can progress to permanent loss. Prompt evaluation and treatment of otitis media, and hearing testing after episodes associated with language delay or learning concerns, help catch acquired conductive or sensorineural loss early."
  }
 ],
 "clinical": [
  {
   "title": "Evaluation and referral",
   "content": "In a newborn who fails hearing screening (OAE and/or ABR), refer promptly to a multidisciplinary center for audiology, otolaryngology, and speech pathology evaluation and treatment; add a genetics consultation, since roughly half of sensorineural hearing loss has a genetic etiology and genetics can clarify diagnosis, prognosis, and associated risks. If auditory neuropathy is suspected, ABR is the appropriate screening/diagnostic modality rather than OAE alone. For a child old enough to cooperate (generally by age 4), obtain pure tone audiometry with air and bone conduction to characterize the type and degree of loss. Order hearing testing in any child with language delay, learning problems, or suspected hearing loss, including after episodes of acute otitis media or otitis media with effusion, since the associated conductive loss (typically 15\u201340 dB, average ~27 dB) can otherwise go unrecognized and compound developmental risk. When counseling families, emphasize that intervention initiated within the birth-to-3-year window has the greatest capacity to prevent downstream speech, language, academic, and social-emotional consequences, and direct them to family-facing resources (e.g., the AAP Early Hearing Detection and Intervention program, babyhearing.org) for education and support during the diagnostic and intervention process."
  }
 ]
}