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Hearing Loss
Scott A. Wiltz, MD, MPH, FAAFP
image BASICS
DESCRIPTION
  • Decrease in the ability to comprehend sound. It can be partial, complete, unilateral, or bilateral.
  • Types of hearing loss include conductive hearing loss (CHL or air-bone gap), sensorineural hearing loss (SNHL), or mixed hearing loss.
  • System(s) affected: auditory; external and middle ear (CHL) or inner ear (SNHL)
EPIDEMIOLOGY
  • All ages affected; common in children (CHL) and elderly (SNHL)
  • Usually more severe at an earlier age in men
Incidence
  • 37% of people >60 years of age
  • At least 1.4 million children (≤18 years of age)
  • Sudden sensorineural hearing loss (SSHL) occurs in 5 to 20 per 100,000 persons.
Prevalence
Hearing loss has increased in individuals aged ≥3 years from 13.2 million in 1971 to 37.5 million in 2004.
Geriatric Considerations
  • ˜80% of people aged >85 years have hearing loss.
  • Hearing aids are underused.
  • Loss of communication is a source of emotional stress and a physical risk for the elderly.
Pediatric Considerations
  • Congenital hearing loss
    • 1 to 6/1,000 infants have hearing loss.
    • Mandatory screening in >97% of newborns with otoacoustic emission (OAE) and auditory brainstem response (BR) testing
  • Audiologic testing after major intracranial infection (meningitis)
Pregnancy Considerations
  • Otosclerosis can worsen during pregnancy.
  • Maternal infections cause permanent pediatric hearing loss.
ETIOLOGY AND PATHOPHYSIOLOGY
  • CHL: Hearing loss can result from middle ear effusion, obstruction of canal (cerumen/foreign body, osteomas/exostoses, cholesteatoma, tumor), loss of continuity (ossicular discontinuity), stiffening of the components (myringosclerosis, tympanosclerosis, and otosclerosis), and loss of the pressure differential across the tympanic membrane (TM) (perforation).
  • SNHL: damage along the pathway from oval window, cochlea, auditory nerve, and brainstem. Examples include vascular/metabolic insult, mass effect, infection and inflammation, and acoustic trauma.
    • Noise-induced hearing loss is caused by acoustic insult that affects outer hair cells in the organ of Corti, causing them to be less stiff. Over time, severe damage occurs with fusion and loss of stereocilia; eventually may progress to inner hair cells and auditory nerve as well.
  • Large vestibular aqueduct or superior canal dehiscence: Third mobile window shunts acoustic energy away from cochlea.
Genetics
  • Connexin 26 (13q11-13q12): most common cause of nonsyndromic genetic hearing loss
  • Mitochondrial disorders (may predispose to aminoglycoside ototoxicity)
  • Otosclerosis: familial
  • Most common congenital syndromes
    • Hemifacial microsomia
    • Stickler syndrome
    • Congenital cytomegalovirus
    • Usher syndrome
    • Branchio-oto-renal syndrome
    • Pendred syndrome
    • CHARGE association
    • Neurofibromatosis type 2
    • Waardenburg syndrome
RISK FACTORS
  • Conductive
    • Chronic sinusitis; allergy
    • Cigarette smoking
    • Sleep apnea with continuous positive airway pressure (CPAP) use
    • Adenoid hypertrophy; nasopharyngeal mass
    • Eustachian tube dysfunction
    • Neuromuscular disease
    • Family history/heredity
    • Prematurity and low birth weight
    • Craniofacial abnormalities (e.g., cleft palate, Down syndrome)
    • Third mobile window (superior canal dehiscence or large vestibular aqueduct)
  • Sensorineural
    • Aging/older age
    • Loud noise/acoustic trauma
    • Dizziness/vertigo: especially Ménière disease or history of labyrinthitis
    • Medications (aminoglycosides, loop diuretics, quinine, aspirin, chemotherapeutic agents)
    • Bacterial meningitis
    • Head trauma
    • Atherosclerosis
    • Vestibular schwannoma/skull base neoplasm
    • Previous ear surgery
  • Sensorineural, pediatric specific
    • Postnatal asphyxia
    • Mechanical ventilation lasting ≥5 days
    • In utero infections (toxoplasmosis, other agents, rubella, cytomegalovirus, herpes simplex [TORCH] syndrome)
    • Toxemia of pregnancy
    • Maternal diabetes
    • Rh incompatibility
    • Prematurity or birth weight < 1,500 g
    • Hyperbilirubinemia; exchange transfusions
    • Anomalous temporal bone (Mondini or large vestibular aqueduct)
    • Infectious diseases: chickenpox, measles, encephalitis, influenza, mumps
GENERAL PREVENTION
  • Limit noise exposure; use hearing protection.
  • Avoid ear canal instrumentation (e.g., cotton swabs).
  • Limit ototoxic medications.
image DIAGNOSIS
PHYSICAL EXAM
  • A simple 512-Hz tuning fork test lateralizes to unaffected ear in sudden SNHL (emergency) and lateralizes to the affected ear in CHL (not an emergency).
  • Whispering screen: A whisper heard from ˜2 feet away is a good screen for intact hearing. Patients with SNHL have difficulty with this because their hearing loss is usually in the high frequency range.
  • 512-Hz tuning fork tests:
    • Sensorineural loss
      • Placed on the forehead: lateralizes to nonaffected ear (Weber test)
      • Base of tuning fork placed on the mastoid and then fork end placed next to ear; heard louder next to ear (Rinne test)
    • Conductive loss
      • Placed on the forehead or teeth lateralizes to affected or symptomatic ear
      • Placed on the mastoid and then next to ear; heard louder behind the ear on the side of conductive deficit
  • Otoscopy: Assess for deformity, canal patency, and otorrhea; TM integrity/retraction/mobility with insufflation, canal, or middle ear mass.
  • Facial symmetry
  • Cranial nerve exam
  • Nasopharyngoscopy: adenoid hypertrophy or nasopharyngeal mass (mandatory in adult patient with new unilateral serous effusion)
  • Pediatric: Survey for syndromic anomalies.
P.445

DIFFERENTIAL DIAGNOSIS
  • Conductive
    • Cerumen impaction/foreign body
    • Perforation of TM
    • Middle ear fluid (serous otitis media)
    • Acute otitis media/adhesive otitis media
    • Ossicular erosion (infection, cholesteatoma)
    • Myringosclerosis/tympanosclerosis
    • Temporal bone fracture
    • Otosclerosis
    • Glomus tumor
  • Sensorineural
    • Presbycusis (hearing loss related to aging)
    • Noise-induced (recreational, occupational)
    • Ménière disease
    • Ototoxicity (aspirin, aminoglycosides)
    • Viral labyrinthitis
    • Cerebellopontine angle tumor
    • Large vestibular aqueduct syndrome
    • Syndromic hearing loss
    • Congenital cochlear malformation
    • Syphilis
    • Cytomegalovirus; rubella
    • Temporal bone fracture
    • Metabolic (hyper-/hypothyroidism)
    • Paget disease
    • Perilymphatic (inner ear) fistula
DIAGNOSTIC TESTS & INTERPRETATION
Often, labs are not needed. If indicated
  • MRI of the brain and brainstem with gadolinium to evaluate SNHL in congenital, early onset, and asymmetric hearing loss
  • Fine-cut CT temporal bones without contrast may help in the evaluation of CHL.
  • Any pediatric patient with SNHL: Consider genetic testing for connexin 26, mitochondrial studies.
  • TORCH screening (congenital infection)
  • Rapid plasma reagin (RPR) or Venereal Disease Research Laboratory (VDRL) confirmed by fluorescent treponemal antibody absorption (FTA-ABS)
  • Lyme titer in endemic areas
  • Antinuclear antibodies and sedimentation rate as a screen for autoimmune disease
  • Pendred syndrome (goiter, mental retardation + SNHL): perchlorate test, thyroid function tests
  • Alport syndrome (nephritis + SNHL): urinalysis, renal function tests
  • Jervell and Lange-Nielsen syndrome (syncope, family history of sudden death + profound SNHL): ECG
Diagnostic Procedures/Other
  • Audiometry: pure tone (air and bone), speech testing, and impedance (middle ear pressure) testing
  • Tympanometry: Type B or C tympanograms indicate fluid or retraction, respectively. Negative middle ear peak pressures were seen even with normal (type A) tympanograms.
  • Other tests
    • Auditory brainstem response
    • OAEs: “echo” of the cochlea
    • Behavioral (visual reinforcement) audiometry; used in children 6 months to 5 years old
  • Myringotomy and tubes can be considered for persistent fluid with hearing loss.
Test Interpretation
Varies depending on etiology
image TREATMENT
Hearing rehabilitation:
  • Personal amplifiers, situation-specific amplification (e.g., amplified phone), or personal hearing aids can be considered for any individual who has significant communication difficulties due to hearing loss.
  • Cochlear implants for patients with bilateral severe to profound hearing loss who no longer derive benefit from hearing aids
MEDICATION
  • Depends on cause
  • Any sudden SNHL (usually unilateral) is a medical emergency; obtain a hearing testing and start steroid therapy.
  • Treatment should begin ASAP, ideally within 1 to 2 weeks of onset with high-dose oral steroids: 1 mg/kg or 60 to 100 mg/day prednisone or 12 to 16 mg/day dexamethasone for 7 to 14 days, followed by a taper: For patients who cannot tolerate systematic steroids, intratympanic steroids are equally effective (1)[A].
    • Clinical practical guidelines for sudden hearing loss include the following (2)[C]:
      • Distinguishing SNHL from CHL; testing for bilateral sudden hearing loss in patients with unilateral sudden hearing loss; obtaining an MRI, auditory brainstem response, or audiometric follow-up to evaluate for retrocochlear pathology; offer intratympanic steroid perfusion for refractory cases after initial management fails to treat idiopathic sudden SNHL (ISSNHL) and follow-up within 6 months of diagnosis.
      • May offer corticosteroids as initial therapy to patients with ISSNHL and hyperbaric oxygen within 3 months of ISSNHL diagnosis
      • Recommended against prescribing antivirals, thrombolytics, vasodilators, vasoactive substances, or antioxidants to patients with ISSNHL
      • Also recommended against routine laboratory tests in patients with ISSNHL
ISSUES FOR REFERRAL
  • Audiology: If hearing loss is suspected, refer to audiology for formal evaluation. Audiologists also provide hearing aid options and maintenance.
  • Genetics: if congenital syndrome or familial hearing loss is suspected
  • Speech therapist: if speech delay or speech impediment is present
  • Endocrinology: Pendred syndrome, other associated endocrine disorder (hypo-/hyperthyroidism)
  • Cardiology: Jervell and Lange-Nielsen syndrome
  • Ophthalmology: Usher syndrome
  • Neurology and neurosurgery: cerebellopontine angle (CPA) lesion, intracranial complication of middle ear disease
SURGERY/OTHER PROCEDURES
  • CHL often has surgical options for repair.
    • Tympanostomy and tube placement
    • Tympanoplasty
    • Mastoidectomy
    • Ossicular chain reconstruction
    • Stapedectomy/stapedotomy
    • Canaloplasty
  • Those with profound bilateral SNHL may qualify for cochlear implantation.
image ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
Patient Monitoring
Audiogram and clinical exam are the primary means of monitoring patient. Patients with hearing assistive devices benefit from audiology involvement.
DIET
Salt restriction to 2 g/day is helpful for patients with Ménière disease.
PATIENT EDUCATION
National Institute on Deafness and Other Communication Disorders (NIDCD): http://www.nidcd.nih.gov/health/hearing/Pages/Default.aspx
PROGNOSIS
  • SNHL is usually permanent and may be progressive. However, amplification devices (e.g., hearing aids) may help improve functionality.
  • ISSNHL may recover spontaneously in 32-70% of cases, but urgent referral and treatment is recommended to maximize recovery. No factors have been proven to predict recovery (3).
REFERENCES
1. Spear SA, Schwartz SR. Intratympanic steroids for sudden sensorineural hearing loss: a systematic review. Otolaryngol Head Neck Surg. 2011;145(4):534-543.
2. Stachler RJ, Chandrasekhar SS, Archer SM, et al. Clinical practice guideline: sudden hearing loss. Otolaryngol Head Neck Surg. 2012;146(3 Suppl): S1-S35.
3. Walling AD, Dickson GM. Hearing loss in older adults. Am Fam Physician. 2012;85(12):1150-1156.
Codes
&NA;
ICD10
  • H91.90 Unspecified hearing loss, unspecified ear
  • H90.2 Conductive hearing loss, unspecified
  • H90.5 Unspecified sensorineural hearing loss
Clinical Pearls
&NA;
  • In sudden hearing loss, if a 512-Hz tuning fork test (Weber test) lateralizes to the unaffected ear, suspect sensorineural causes (emergent evaluation needed), but if it lateralizes to the affected ear, the diagnosis is CHL (not an emergency).
  • ~80% of people aged >85 years have hearing loss, encourage screening and treatment, especially in patients with early dementia.