Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android

For further information, see CMDT Part 8-01: Hearing Loss

Key Features

Essentials of Diagnosis

  • Two main types of hearing loss

    • Conductive

    • Sensorineural

  • Most commonly caused by cerumen impaction, transient eustachian tube dysfunction, or age-related hearing loss

General Considerations

Conductive hearing loss

  • Results from a mechanical disruption of the external auditory canal or middle ear

  • Four mechanisms, each resulting in impairment of the passage of sound vibrations to the inner ear

    • Obstruction (eg, cerumen impaction)

    • Mass loading (eg, middle ear effusion)

    • Stiffness (eg, otosclerosis)

    • Discontinuity (eg, ossicular disruption)

  • Causes include

    • Cerumen impaction

    • Transient eustachian tube dysfunction due to upper respiratory tract infection

    • Chronic ear infection

    • Trauma

    • Otosclerosis

    • Perforations of the tympanic membrane

  • Often correctable with medical or surgical therapy, or both

Sensorineural hearing loss

  • Common in adults and generally results from deficits of the inner ear or central (brain) auditory pathway

  • Age-related hearing loss

    • Most common form of sensorineural hearing loss

    • Manifests as a gradually progressive, predominantly high-frequency hearing loss

  • Rate of hearing loss

    • Hearing loss may be gradual or sudden

    • Sudden (idiopathic) sensorineural hearing loss is an otologic emergency

  • Causes are either sensory or central and include

    • Deterioration of the cochlea, usually due to loss of sensory hair cells within the organ of Corti

    • Excessive noise exposure

    • Head trauma

    • Ototoxic medications (eg, cisplatin-based chemotherapy)

    • Systemic diseases

    • Deficits at the level of the central auditory pathway (eg, lesions involving the eighth cranial nerve, auditory nuclei, ascending tracts, or auditory cortex)

      • Acoustic neuroma

      • Multiple sclerosis

      • Auditory neuropathy

Clinical Findings

Symptoms and Signs

  • Reduction in hearing level

  • Weber test

    • Tuning fork is placed directly on the forehead or front teeth

    • In conductive hearing losses, the sound appears louder in the poorer-hearing ear, whereas in sensorineural hearing losses it radiates to the better-hearing ear

  • Rinne test

    • Tuning fork is placed alternately on the mastoid bone (bone conduction) and in front of the ear canal (air conduction)

    • In conductive losses > 25dB, bone conduction sounds louder than air conduction

Differential Diagnosis

Conductive (external or middle ear)

  • Cerumen (ear wax) impaction

  • Transient auditory tube dysfunction

  • Acute or chronic otitis media

  • Mastoiditis

  • Otosclerosis

  • Disruption of ossicles

  • Trauma or barotrauma

  • Glomus tympanicum (middle ear tumor)

  • Paget disease


  • Presbycusis (age related)

  • Excessive noise exposure

  • Ménière disease (endolymphatic hydrops)

  • Labyrinthitis

  • Head trauma

  • Ototoxicity

  • Occlusion of ipsilateral auditory artery

  • Hereditary hearing loss

  • Autoimmune

    • Systemic lupus erythematosus

    • Granulomatosis with polyangiitis

    • Cogan syndrome

  • Other systemic causes

    • Diabetes mellitus

    • Hypothyroidism

    • Hyperlipidemia

    • Chronic kidney disease

    • Infections


  • Acoustic neuroma

  • Multiple sclerosis

  • Cerebrovascular disease


Diagnostic Procedures


Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.