Hypothesis: Otosclerosis is a disease of unknown etiology causing conductive or sensorineural hearing loss. Persistent measles virus infection of the otic capsule is considered to be one of the etiologic factors in otosclerosis.
Background: Determinants of measles virus infection and reactive inflammation were studied in otosclerosis. The presence of measles virus was shown in otosclerotic patients by reverse-transcription polymerase chain reaction (RT-PCR) amplification of the viral RNA. No report is available, however, on the types and features of paracrine cytokines in otosclerosis.
Methods: Nucleic acid was extracted from stapes footplate samples of clinically otosclerotic patients. Measles virus nucleoprotein RNA was amplified by seminested RT-PCR. Tumor necrosis factor (TNF)-alpha mRNA expression was detected by RT-PCR in otosclerotic bone and was correlated with preoperative audiologic findings and measles virus positivity.
Results: Among 154 clinically otosclerotic patients, 99 stapes footplate specimens contained measles virus RNA. TNF-alpha mRNA was detectable in 88 virus-positive and in 6 virus-negative stapes footplates. There was no detectable TNF-alpha mRNA expression in virus negative cases.
Conclusion: The etiologic role of measles virus in the pathogenesis of otosclerosis should be considered. Detection of TNF-alpha mRNA demonstrates activated osteoclast functions and inflammatory pathways in otosclerotic stapes footplates associated with measles virus presence. Virus-associated and virus-negative pathomechanisms of otosclerosis should be distinguished.