Nongenetic Systemic Conditions & Infectious Causes of Hearing and Balance Disorders
Key Takeaways
Congenital cytomegalovirus (CMV) is the most common nongenetic cause of congenital sensorineural hearing loss; testing must occur within 21 days of birth to confirm congenital infection, and the loss can be delayed or progressive.
Autoimmune inner ear disease causes rapidly progressive, usually bilateral and asymmetric sensorineural loss over weeks to months and may respond to corticosteroids, so it needs prompt otolaryngology referral.
Bacterial meningitis is the leading cause of acquired childhood sensorineural loss; labyrinthitis ossificans can develop within weeks, so audiologic evaluation and implant referral must not be delayed.
Herpes zoster oticus (Ramsay Hunt syndrome) combines ear pain, vesicles, and ipsilateral facial paralysis, sometimes with sensorineural loss and vertigo, and needs urgent antiviral and steroid treatment.
Severe neonatal hyperbilirubinemia damages brainstem auditory pathways and classically produces auditory neuropathy spectrum disorder, with present OAEs but an absent or abnormal ABR.
Nongenetic Systemic Conditions & Infectious Causes of Hearing and Balance Disorders
Genetic syndromes and outer, middle, and inner ear pathologies are covered elsewhere in this guide. This section covers the two remaining pathophysiology topics on the Praxis Audiology blueprint: nongenetic systemic health conditions that affect hearing and balance, and infectious pathologies. For each condition, know the typical audiologic pattern, the red flags that require medical referral, and what follow-up the audiologist should recommend.
Nongenetic Systemic Health Conditions
Diabetes Mellitus
- Adults with diabetes have roughly twice the prevalence of hearing impairment of adults without it (U.S. NHANES data).
- Proposed mechanisms include microangiopathy of the stria vascularis and cochlear vessels, and auditory neuropathy from metabolic damage.
- Typical pattern: gradual, bilateral, symmetric, high-frequency sensorineural loss. Diabetes is also a risk factor for necrotizing (malignant) otitis externa and slows healing after ear procedures.
Cardiovascular and Cerebrovascular Disease
- Hypertension, hyperlipidemia, smoking, and atherosclerosis are associated with sensorineural hearing loss, probably through reduced cochlear blood flow. The cochlea depends on a single end artery (the labyrinthine artery), so it has no collateral supply.
- Anterior inferior cerebellar artery (AICA) stroke can cause sudden hearing loss and vertigo together because AICA supplies the labyrinthine artery. Sudden hearing loss with vertigo and any neurologic sign is an emergency.
Renal Disease
- Chronic kidney disease is associated with sensorineural loss. Shared risk factors include hypertension and diabetes, and treatment can involve ototoxic drugs such as loop diuretics and aminoglycosides.
- Alport syndrome links kidney disease and hearing loss, but it is genetic (collagen IV genes) and belongs with the syndromes.
Autoimmune Inner Ear Disease (AIED)
- Primary AIED: rapidly progressive, usually bilateral and often asymmetric sensorineural loss that worsens over weeks to months. It may fluctuate and may include tinnitus, aural fullness, and vestibular symptoms.
- It is uncommon (well under 1% of hearing loss), but it matters because it can respond to corticosteroids and other immunosuppressive treatment. Progression over weeks to months distinguishes it from sudden sensorineural loss (within 72 hours) and from slow presbycusis.
- Secondary autoimmune disease affecting the ear includes systemic lupus erythematosus, rheumatoid arthritis, granulomatosis with polyangiitis (which often presents with otitis media with effusion and sensorineural loss), relapsing polychondritis, and Cogan syndrome (interstitial keratitis with audiovestibular dysfunction).
Thyroid Disorders
- Untreated congenital hypothyroidism can cause sensorineural hearing loss, one reason newborn thyroid screening matters.
- Pendred syndrome (goiter with enlarged vestibular aqueduct) is genetic; an enlarged thyroid in a child with fluctuating or progressive hearing loss should prompt referral.
Multiple Sclerosis (MS)
- Demyelination of brainstem auditory and vestibular pathways can cause sudden or fluctuating hearing loss, vertigo, and central eye-movement signs.
- Typical findings: abnormal ABR (prolonged interpeak latencies or poor waveform morphology) with near-normal pure-tone thresholds, abnormal acoustic reflexes, and central auditory processing deficits.
Hyperbilirubinemia and Kernicterus
- Severe neonatal hyperbilirubinemia damages brainstem auditory nuclei and the auditory nerve. It is a classic cause of auditory neuropathy spectrum disorder (ANSD): present OAEs or cochlear microphonic, but absent or abnormal ABR.
- JCIH lists hyperbilirubinemia requiring exchange transfusion as a risk factor for hearing loss.
Other Nongenetic Conditions
- Paget disease of bone: temporal bone remodeling can cause mixed hearing loss in older adults.
- Temporal bone fracture: fractures that spare the otic capsule more often cause conductive loss (hemotympanum, ossicular disruption); fractures that violate the otic capsule cause severe sensorineural loss, vertigo, and often facial nerve injury.
- Vitamin B12 deficiency and anemia have been associated with hearing loss and imbalance in some studies.
Infectious Pathologies
Congenital Infections
| Infection | Hearing and Balance Effects | Key Facts |
|---|---|---|
| Cytomegalovirus (CMV) | Sensorineural loss that may be present at birth or appear later and progress; can be unilateral or bilateral | Most common nongenetic cause of congenital sensorineural loss. About 1 in 200 newborns is infected; about 10% have symptoms at birth. Hearing loss occurs in roughly one-third or more of symptomatic infants and about 10% of asymptomatic infants. |
| Rubella | Sensorineural loss, often severe; most common feature of congenital rubella syndrome | Also cataracts and heart defects (patent ductus arteriosus); risk is highest with first-trimester infection; now rare where MMR vaccination is routine |
| Toxoplasmosis | Sensorineural loss | Part of the TORCH group; also chorioretinitis and hydrocephalus |
| Syphilis | Progressive or fluctuating sensorineural loss and vertigo | Congenital syphilis can produce Hutchinson's triad (notched incisors, interstitial keratitis, sensorineural loss); U.S. cases rose sharply in the 2020s |
| Herpes simplex virus | Sensorineural loss | Neonatal infection |
| Zika virus | Sensorineural loss | Congenital Zika syndrome includes microcephaly; listed by JCIH with other in utero infections |
CMV testing: Because CMV can be treated, many programs test infants who do not pass newborn hearing screening for CMV. Testing (saliva or urine PCR) must be done within the first 21 days of life to tell congenital infection from infection acquired after birth. Antiviral treatment (valganciclovir) started within the first month can improve hearing outcomes for infants with symptomatic congenital CMV. Infants with congenital CMV need regular audiologic monitoring because the loss can be delayed or progressive.
Acquired Infections
- Bacterial meningitis: the most common cause of acquired sensorineural loss in childhood. Streptococcus pneumoniae carries the highest risk; Hib and pneumococcal vaccines have reduced cases. Inflammation can cause labyrinthitis ossificans (new bone in the cochlea) within weeks, so children need audiologic evaluation as soon as they are medically stable. Children with severe-to-profound loss need urgent cochlear implant evaluation before ossification blocks electrode insertion.
- Mumps: classically causes sudden, unilateral, often profound sensorineural loss.
- Measles: can cause bilateral sensorineural loss, and complications of measles can include encephalitis.
- Herpes zoster oticus (Ramsay Hunt syndrome): reactivation of varicella-zoster virus in the geniculate ganglion causes ear pain, vesicles on the pinna or ear canal, and facial paralysis on the same side. Sensorineural loss and vertigo can also occur. Treatment is antiviral medication with corticosteroids, so prompt medical referral is essential.
- Labyrinthitis versus vestibular neuritis: viral labyrinthitis causes acute vertigo with hearing loss, whereas vestibular neuritis causes acute vertigo without hearing loss. Bacterial (suppurative) labyrinthitis can follow otitis media or meningitis and can destroy cochlear function.
- Otitis media: acute otitis media is usually caused by S. pneumoniae, nontypeable Haemophilus influenzae, or Moraxella catarrhalis. Complications include perforation, mastoiditis, and, rarely, labyrinthitis or meningitis.
- Otitis externa: commonly caused by Pseudomonas aeruginosa or Staphylococcus aureus; fungal infection (otomycosis) is also common. Necrotizing otitis externa in older adults with diabetes or immunosuppression causes severe pain and granulation tissue in the canal and can spread to the skull base and facial nerve, so it requires urgent referral.
- HIV: associated with sensorineural and conductive loss, from the infection, opportunistic infections, or treatment.
Clinical Pearls for the Exam
- Sensorineural loss that progresses over weeks to months suggests AIED; ask about other autoimmune symptoms and refer to otolaryngology.
- Congenital CMV should be considered for any infant who does not pass newborn screening, and testing must happen within 21 days.
- Hearing loss after bacterial meningitis requires prompt evaluation because ossification can rule out implantation later.
- Ear pain, vesicles, and facial weakness together suggest Ramsay Hunt syndrome, a medical emergency for the facial nerve.
A 42-year-old reports that hearing in both ears has worsened over the past 6 weeks, with fluctuating fullness and occasional imbalance. Audiometry shows a moderate sensorineural loss in the right ear and a mild sensorineural loss in the left ear, both worse than an audiogram from 2 months ago. Which condition and action are most consistent with these findings?
Presbycusis; recommend bilateral hearing aids and annual monitoring without medical referral
Noise-induced hearing loss; counsel on hearing protection and repeat testing in one year
Autoimmune inner ear disease; refer promptly to otolaryngology because treatment may preserve hearing
Otosclerosis; schedule tympanometry and acoustic reflex testing, then counsel about a hearing aid trial
A 9-year-old was hospitalized two weeks ago with Streptococcus pneumoniae meningitis and is now medically stable. Parents report that the child no longer responds to speech. Why is prompt audiologic evaluation especially important for this child?
New bone can form in the cochlea within weeks, so any needed cochlear implant evaluation must not be delayed.
Meningitis causes temporary conductive loss that resolves within days and needs only tympanometry to confirm.
Hearing loss from meningitis always recovers by six months, so early testing is mainly used to reassure parents.
Testing must wait at least one year after meningitis, because earlier results are invalid and unreliable.
A 67-year-old presents with severe right ear pain, a rash of small blisters in the concha, and new weakness of the right side of the face. Which action is most appropriate?
Perform cerumen removal and tympanometry, then schedule a routine hearing aid evaluation for next month
Diagnose Bell's palsy and recommend facial exercises before scheduling routine audiometric follow-up
Begin vestibular rehabilitation exercises, because facial weakness is a common side effect of vertigo
Refer the same day for treatment of probable Ramsay Hunt syndrome, then complete audiologic testing
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