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Ossicular chain disruption

Ossicular chain disruption (or ossicular discontinuity) is loss of normal alignment between the three ossicles. The condition is a cause of conductive hearing loss.

Epidemiology

Exact incidence and prevalence are not known. Hearing loss associated with temporal bone fractures in children occurs in 75%, but persists beyond 1 month in less than 15%.

Causes are:

Clinical presentation

Sudden conductive hearing loss in traumatic cases. The hearing loss may be due to ossicular chain disruption or middle ear haemorrhage. Sensorineural hearing loss may coexist, e.g. in temporal bone fractures that have a transverse component.

Ancillary features include haemotympanum and/or otorrhoea.

Imaging

Temporal bone CT

Loss of normal joint alignments: 

  • incus and malleus are normally closely apposed, resembling a scoop of ice cream in a cone with the malleus representing the ice cream and the incus represents the cone
CT - virtual endoscopy

3D reconstruction aids surgical planning.

Management

A conductive hearing loss of more than 30 dB persisting  6 months post injury is considered an indication of reconstruction of the ossicular chain:

  • surgical (acute or delayed) - relocation; reconstruction with hydroxyapatite prosthese; cartilage allografts
  • conservative - hearing aids

See also

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