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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 or transient auditory tube dysfunction from upper respiratory tract infection

General Considerations

Conductive loss

  • 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 effect (eg, otosclerosis)

    • Discontinuity (eg, ossicular disruption)

  • Generally more correctable than sensory and neural losses

Sensorineural loss

  • Sensory and neural causes of hearing loss are difficult to differentiate due to testing methodology, thus often referred to as "sensorineural"

  • Sensory loss

    • Most common form is a gradually progressive, predominantly high-frequency loss with advancing age (presbyacusis)

    • Other common causes include

      • Excessive noise exposure

      • Head trauma

      • Systemic diseases

    • Sensory hearing loss is usually not correctable but may be prevented or stabilized

    • However, sudden sensory hearing loss may respond to corticosteroids if delivered within several weeks of onset

  • Neural loss

    • Occurs with lesions involving the eighth nerve, auditory nuclei, ascending tracts, or auditory cortex

    • It is the least common clinically recognized cause of hearing loss

    • Causes include

      • Acoustic neuroma

      • Multiple sclerosis

      • Cerebrovascular disease

Clinical Findings

Symptoms and Signs

  • Reduction in hearing level

  • Weber test

    • Tuning fork is placed on the forehead or front teeth

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

  • Rinne test

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

    • In conductive losses > 25dB, bone conduction exceeds air conduction, whereas in sensorineural losses, the opposite is true

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

  • Formal audiometric studies are performed in a soundproofed room

  • Pure-tone thresholds in decibels (dB) are obtained over the range of 250–8000 Hz for both air and bone conduction

  • In conductive losses, there is a gap between the air and bone thresholds

  • In sensorineural losses,...

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