Ossicular chain disruption

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

Epidemiology

Exact incidence ~~and~~ 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%.

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. intemporal bone fractures that have a transverse component.

Ancillary features include haemotympanum and/or otorrhoea.

Pathology

Causes are:

traumatic
- temporal bone fracture, especiallly longitudinal type
- blast injuries
- rare causes e.g. lightning strike ²
atraumatic
- congenital
- erosive disease
  - cholesteatoma
  - chronic middle ear infection

Radiographic features

CT

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.

Treatment and prognosis

Conductive hearing loss of more than 30 dB persisting six ~~months~~ 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

-<p><strong>Ossicular chain disruption</strong> (or <strong>ossicular discontinuity</strong>) is loss of normal alignment between the three <a title="Inner ear" href="/articles/inner-ear">inner ear</a> <a href="/articles/middle-ear-ossicles">ossicles</a>. The condition is a cause of <a href="/articles/conductive-hearing-loss">conductive hearing loss</a>.</p><h4>Epidemiology</h4><p>Exact incidence and prevalence are not known. Hearing loss associated with <a href="/articles/temporal-bone-1">temporal bone</a> fractures in children occurs in 75%, but persists beyond 1 month in less than 15%.</p><h4>Clinical presentation</h4><p>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 <a href="/articles/temporal-bone-fractures-1">temporal bone fractures</a> that have a transverse component.</p><p>Ancillary features include haemotympanum and/or otorrhoea.</p><h4>Pathology</h4><p>Causes are:</p><ul>
+<p><strong>Ossicular chain disruption</strong> (or <strong>ossicular discontinuity</strong>) is loss of normal alignment between the three <a href="/articles/inner-ear">inner ear</a> <a href="/articles/middle-ear-ossicles">ossicles</a>. The condition is a cause of <a href="/articles/conductive-hearing-loss">conductive hearing loss</a>.</p><h4>Epidemiology</h4><p>Exact incidence and prevalence are not known. Hearing loss associated with <a href="/articles/temporal-bone-1">temporal bone</a> fractures in children occurs in 75%, but persists beyond 1 month in less than 15%.</p><h4>Clinical presentation</h4><p>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 <a href="/articles/temporal-bone-fractures-1">temporal bone fractures</a> that have a transverse component.</p><p>Ancillary features include haemotympanum and/or otorrhoea.</p><h4>Pathology</h4><p>Causes are:</p><ul>
-<a href="/articles/incus">incus</a> and <a href="/articles/malleus">malleus</a> 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</li></ul><h6>CT - virtual endoscopy</h6><p>3D reconstruction aids surgical planning.</p><h4>Treatment and prognosis</h4><p>Conductive hearing loss of more than 30 dB persisting six months post injury is considered an indication of reconstruction of the ossicular chain:</p><ul>
+<a href="/articles/incus">incus</a> and <a href="/articles/malleus">malleus</a> 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</li></ul><h6>CT - virtual endoscopy</h6><p>3D reconstruction aids surgical planning.</p><h4>Treatment and prognosis</h4><p>Conductive hearing loss of more than 30 dB persisting six months post injury is considered an indication of reconstruction of the ossicular chain:</p><ul>

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