Intracochlear Bleeding Enhances Cochlear Fibrosis and Ossification: An Animal Study

Area of Science:

• Otolaryngology
• Neurosurgery
• Immunology

Background:

• Cochlear implantation is a common procedure for hearing restoration.
• Potential complications include intracochlear bleeding, which may affect surgical outcomes.
• The impact of intracochlear bleeding on cochlear inflammation and healing remains unclear.

Purpose of the Study:

• To investigate the effects of intracochlear bleeding during cochleostomy on cochlear inflammation and residual hearing.
• To evaluate the role of inflammatory cytokines in response to intracochlear bleeding.
• To assess the long-term histopathological consequences of intracochlear bleeding.

Main Methods:

• A guinea pig model was used to simulate intracochlear bleeding during cochleostomy.
• Auditory brainstem response (ABR) was measured to assess hearing thresholds.
• Cytokine levels (Interleukin-1β, Interleukin-10, Tumor Necrosis Factor-α, Nitric Oxide Synthase 2) were quantified.
• Histopathological examination assessed hair cell damage, fibrosis, and ossification.

Main Results:

• Blood-injected ears showed significantly greater ABR threshold shifts compared to control ears (p<0.05).
• Key inflammatory cytokines were significantly elevated in blood-injected ears one day post-surgery, with IL-1β sustained for three days (p<0.05).
• More severe hair cell damage, fibrosis, and ossification were observed in ears with intracochlear bleeding.

Conclusions:

• Intracochlear bleeding during cochleostomy exacerbates cochlear inflammation in an animal model.
• This inflammation contributes to increased hearing loss, hair cell damage, and adverse histopathological changes like fibrosis and ossification.
• Minimizing intracochlear bleeding during cochlear surgery may be crucial for preserving hearing and improving outcomes.