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Purulent labyrinthitis is characterized by the
presence of large numbers of inflammatory
cells. Bacteria may invade
the inner ear during acute or chronic otitis media or meningitits, from
distant or systemic infections, or following planned or inadvertent
opening of the inner ear during surgery.
Other pathologic changes of the inner ear include: severe
necrosis of the cochlear structures, vasodilatation, and hemorrhage.
Clinically, nystagmus is often toward the unaffected side and
permanent hearing loss is
likely.
Higher power view of the basal turn shows
inflammatory cells in the
scala tympani (ST), scala vestibuli (SV), and internal auditory canal (IAC). Reissner’s membrane (arrow) is collapsed with inflammatory
infiltration of the scala media.
This high power view demonstrates the presence of
inflammatory cells in the scala tympani (ST) and scala media (SM). There is severe atrophy of the organ of Corti (O of C).
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Polymorphonuclear leukocytes can be seen scala
tympani (ST) of this high power view of the basal turn.
There is loss of hair cells (arrows).
SM = scala media.
Fibrous labyrinthitis
When labyrinthitis researches the
chronic stage, fibroblasts and fibrous tissue predominate.
Fibrous tissue progressively replaces the cochlear spaces and
structures. This stage
begins two to three months after the onset of infection and may continue
to progress for many years.
Enlarged view of the basal turn
shows fibrous tissue (F) and total loss of the organ of Corti (arrow).
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