Case 4
History:
23-year-old man with profound bilateral sensorineural hearing loss
Findings:
Axial CISS sequence show loss of normal T2 hyperintensity signal of the labyrinth bilaterally, replaced by hypointensity signal suggestive of fibrosis or ossificatin. Corresponding axial T1 before and after contrast showing abnormal enhancement of the labyrinth.
Diagnosis:
Discussion:
Labyrinthitis is defined as the combination of the symptoms of vestibular neuritis with the addition of hearing symptoms. It may be due to a process that affects the inner ear as a whole or due to a process that affects the 8th nerve as a whole. Labyrinthitis is also always attributed to an infection. LO is the pathologic ossification of spaces within the lumen of the bony labyrinth and cochlea that occurs in response to an inflammatory process most often bacterial infection of the inner ear that results in suppurative labyrinthitis.
There are typically 3 characteristic stages of the evolution of labyrinthitis ossificans–acute, fibrous, and ossifying:
- The acute stage is characterized by purulence that fills the perilymphatic spaces and spares the endolymphatic space. Discharge of serofibrinous exudate ensues.
- The fibrous stage is marked by fibroblastic proliferation within the perilymphatic spaces. This proliferation begins approximately 2 weeks following the onset of infection. Angiogenesis is also present.
- The ossifying stage is characterized by bone formation, which can develop in the basal turn of the cochlea as early as 2 months after the onset of infection. CT can show calcifications but typically late in the disease.
