What causes bilateral sensorineural hearing loss in a child?

Bilateral Sensorineural Hearing Loss in Children: Causes

Bilateral sensorineural hearing loss in children is most commonly caused by genetic factors (approximately 30% nonsyndromic, 3-4% syndromic), followed by unknown etiology (32-42%), prenatal infections (particularly cytomegalovirus), perinatal complications, and postnatal infections such as meningitis. 1, 2

Primary Etiologic Categories

Genetic Causes (Most Common Identifiable Cause)

• Nonsyndromic genetic hearing loss accounts for 27-29% of bilateral pediatric sensorineural hearing loss, representing the single largest identifiable cause 1, 3
• Approximately 77% of nonsyndromic cases follow autosomal recessive inheritance, 22% autosomal dominant, and 1% X-linked patterns 4
• Syndromic genetic hearing loss comprises 3-4% of cases, including conditions like Waardenburg syndrome, Usher syndrome, Pendred syndrome, and Jervell and Lange-Nielsen syndrome 4, 1
• Over 90% of children with autosomal recessive profound hearing loss are born to hearing parents, making family history an unreliable screening tool 4

Infectious Causes

Congenital Cytomegalovirus (Leading Infectious Cause)

• CMV is the most common infectious cause of nongenetic sensorineural hearing loss in children 5, 6
• Critically, 35-39% of children with congenital CMV pass newborn hearing screening bilaterally but develop delayed-onset hearing loss, detected at a mean age of 20 months 5
• Among children who refer unilaterally on newborn screening with CMV, 50% later develop hearing loss in the contralateral ear 5

Bacterial Meningitis

• Meningitis (infectious, inflammatory, or neoplastic) causes bilateral sudden hearing loss and is associated with headache, fever, abnormal cerebrospinal fluid, and possible other cranial nerve palsies 4, 2
• Culture-positive postnatal bacterial and viral meningitis is a well-established risk factor for delayed-onset hearing loss 4

Other Viral Infections

• Mumps, herpes simplex virus, varicella zoster virus (Ramsay Hunt syndrome), and HIV can all cause bilateral sensorineural hearing loss 4, 2
• Congenital rubella, syphilis, toxoplasmosis, and herpes are prenatal infections associated with hearing loss 4

Perinatal Complications (9-10% of Cases)

• Prematurity, asphyxia, and complicated perinatal courses account for approximately 10% of bilateral sensorineural hearing loss 1, 3
• NICU stay exceeding 5 days, ECMO, assisted ventilation, hyperbilirubinemia requiring exchange transfusion are significant risk factors 4
• Ototoxic medication exposure (aminoglycosides like gentamicin/tobramycin, loop diuretics like furosemide) during the perinatal period 4

Ototoxic Medications

• Aminoglycosides and cisplatin can cause bilateral sensorineural hearing loss, often with concurrent vestibular loss and oscillopsia 4, 7
• Ototoxin exposure was documented in 13 cases in a comprehensive pediatric bilateral sudden hearing loss review 2

Structural/Anatomic Causes

• Enlarged vestibular aqueduct was identified in 9 cases of pediatric bilateral sudden sensorineural hearing loss 2
• Craniofacial anomalies involving the pinna, ear canal, ear tags, ear pits, and temporal bone anomalies are associated with hearing loss 4

Autoimmune Causes

• Autoimmune inner ear disease presents with fluctuating bilateral hearing loss, often with vertigo 4, 7
• Cogan syndrome causes nonsyphilitic interstitial keratitis, bilateral hearing loss, and vertigo 4

Traumatic Causes

• Significant head trauma, basal skull/temporal bone fractures, and barotrauma can cause bilateral hearing loss 4

Metabolic/Mitochondrial Disorders

• MELAS (metabolic encephalopathy, lactic acidosis, and stroke-like episodes) presents with confusion, elevated lactate, MRI white matter changes, and hearing loss 4
• Other mitochondrial disorders have variable phenotypes and may account for 1-20% of cases depending on population 4

Unknown Etiology

• Despite comprehensive evaluation, 32-42% of bilateral pediatric sensorineural hearing loss remains unexplained 1, 3
• This percentage has declined in recent studies due to advances in genetic testing 1

Critical Clinical Pitfalls

• Passing newborn hearing screening does not exclude congenital CMV-related hearing loss—35% of children with CMV and normal newborn screens develop delayed-onset hearing loss 5
• Unilateral hearing loss on newborn screening warrants CMV testing and long-term audiologic monitoring, as 50% develop contralateral hearing loss 5
• Family history is present in only 28.6% of cases, making it an inadequate sole screening criterion 3
• The average age at diagnosis for bilateral moderate-to-severe hearing loss is approximately 3 years, representing a significant delay in identification 3