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BASICS

Description

  • Decreased ability to perceive and comprehend sound (>25 dB deficit)
  • Types:
  • Conductive hearing loss (CHL): outer/middle ear dysfunction, air-bone gap on audiometry
  • Sensorineural hearing loss (SNHL): inner ear, auditory nerve, or brainstem pathology
  • Mixed hearing loss: combined conductive and sensorineural
  • Sudden hearing loss: rapid subjective hearing impairment over hours to days

Epidemiology

  • Affects all ages, more common with age
  • Prevalence:
  • 20.6% in adults aged 48-59 years
  • Up to 90% in adults >80 years
  • Sudden sensorineural hearing loss (SSHL): 5-27 per 100,000/year
  • Hearing loss linked to cognitive decline and dementia in elderly

Etiology and Pathophysiology

Conductive Hearing Loss (CHL)

  • Causes: middle ear effusion, eustachian tube dysfunction, cerumen impaction, tumors, otosclerosis, TM perforation, ossicular discontinuity
  • Pathophysiology: impaired sound conduction to cochlea

Sensorineural Hearing Loss (SNHL)

  • Causes: noise-induced damage (outer hair cells), vascular/metabolic insults, infections, acoustic trauma
  • Syndromes: large vestibular aqueduct, superior canal dehiscence
  • Genetics: nonsyndromal (connexin 26 mutations common), congenital syndromes (Alport, Stickler)
  • Otosclerosis: familial component

Risk Factors

  • Loud noise exposure
  • Ototoxic medications (aminoglycosides, cisplatin, loop diuretics, NSAIDs, aspirin)
  • Tobacco, alcohol use
  • Skull base tumors (vestibular schwannoma)
  • Ear surgeries
  • Pediatric factors: prematurity, congenital infections (TORCH), hyperbilirubinemia, temporal bone anomalies

General Prevention

  • Limit noise exposure; use hearing protection
  • Avoid ototoxic drugs when possible

Commonly Associated Conditions

  • Tinnitus often coexists

DIAGNOSIS

History

  • Insidious onset, difficulty hearing, especially in noisy environments
  • Rapid onset hearing loss (<3 days) is a medical emergency
  • Associated symptoms: tinnitus, vertigo, ear pain, otorrhea
  • History of ear infections, surgeries, trauma, noise exposure, family history

Physical Exam

  • Whispered voice test (screen for intact hearing)
  • Tuning fork tests (512 Hz):
  • Weber test lateralizes to unaffected ear in SNHL
  • Weber lateralizes to affected ear in CHL
  • Rinne test positive (AC > BC) in normal or SNHL
  • Rinne test negative (BC > AC) in CHL
  • Otoscopy: TM integrity, canal patency, masses
  • Cranial nerve exam
  • Nasopharyngoscopy if unilateral serous effusion in adults

Differential Diagnosis

  • CHL: cerumen impaction, TM perforation, acoustic neuroma
  • SNHL: presbycusis, noise-induced, Ménière disease, viral labyrinthitis, ototoxicity, CPA tumor, temporal bone fracture, metabolic, vasculitis

Diagnostic Tests

  • Audiometry (pure tone air/bone, speech, impedance)
  • Tympanometry (fluid/retraction assessment)
  • MRI brain with gadolinium for asymmetric or sudden SNHL
  • CT temporal bones for CHL evaluation
  • Newborn screening with OAE/ABR
  • Genetic testing for connexin 26 and mitochondrial disorders in pediatric cases
  • Serologic tests: TORCH, RPR/VDRL with FTA-ABS, Lyme titer, ANA, ESR as indicated

TREATMENT

Medical

  • Sudden SNHL: high-dose oral corticosteroids (prednisone 1 mg/kg/day or dexamethasone 12-16 mg/day for 7-14 days with taper)
  • Intratympanic steroid injections for refractory cases
  • Hyperbaric oxygen therapy (HBOT) within 2 weeks of onset as adjunct or salvage
  • Avoid antivirals, thrombolytics, vasodilators, antioxidants in idiopathic SSHL

Surgical

  • CHL: tympanostomy tubes, tympanoplasty, mastoidectomy, ossicular reconstruction, stapedectomy
  • SNHL: cochlear implantation for profound bilateral loss

Additional Therapies

  • Auditory rehabilitation including hearing aids, speech therapy
  • Multidisciplinary approach with audiologists and speech pathologists

ONGOING CARE

Follow-Up

  • Monitor audiogram and clinical status
  • Counsel on noise avoidance and hearing protection
  • Salt restriction and alcohol reduction for Ménière disease

Patient Education

Prognosis

  • SNHL generally permanent and progressive
  • SSHL spontaneous recovery 32-70% with treatment improving outcomes

Complications

  • Chronic middle ear disease (perforations, cholesteatoma)
  • Progressive hearing loss impacting cognition and quality of life

Clinical Pearls

  • Sudden hearing loss with Weber test lateralizing to unaffected ear suggests sensorineural etiology requiring urgent evaluation.
  • Hearing loss is prevalent in elderly and contributes to cognitive decline; screening and rehabilitation are critical.
  • Noise-induced hearing loss is preventable with proper ear protection.

References

  1. Michels TC, Duffy MT, Rogers DJ. Hearing loss in adults: differential diagnosis and treatment. Am Fam Physician. 2019;100(2):98-108.
  2. Bisogno A, Scarpa A, Di Girolamo S, et al. Hearing loss and cognitive impairment: epidemiology, common pathophysiological findings, and treatment considerations. Life (Basel). 2021;11(10):1102.
  3. Shapiro SB, Noij KS, Naples JG, et al. Hearing loss and tinnitus. Med Clin North Am. 2021;105(5):799-811.
  4. Mitchell CO, Morton CC. Genetics of childhood hearing loss. Otolaryngol Clin North Am. 2021;54(6):1081-1092.
  5. Rahne T, Plontke S, Keyßer G. Vasculitis and the ear: a literature review. Curr Opin Rheumatol. 2020;32(1):47-52.