Hearing loss and pneumococcal meningitis: an animal model

Area of Science:

• Otolaryngology
• Infectious Diseases
• Neuroscience

Background:

• Clinical studies on hearing loss from bacterial meningitis have yielded inconsistent findings regarding predisposing factors.
• A precise animal model is needed to investigate the relationship between meningitis and secondary hearing loss.

Purpose of the Study:

• To develop and validate an animal model for studying meningogenic labyrinthitis and associated hearing loss.
• To investigate the correlation between meningitis duration and the incidence/severity of hearing loss.
• To explore the role of the cochlear aqueduct in the progression of hearing impairment.

Main Methods:

• Rabbits were intrathecally inoculated with *Streptococcus pneumoniae* to induce meningitis.
• Auditory-evoked responses were used to measure hearing thresholds before infection and every 12 hours post-infection.
• Temporal bone histology was performed to examine cochlear and surrounding structures.

Main Results:

• All subjects developed profound deafness by an average of 48 hours post-infection.
• Hearing loss incidence and severity strongly correlated with the duration of meningitis.
• Histology revealed acute inflammation in perilymphatic spaces, including the cochlear aqueduct.

Conclusions:

• The developed rabbit model effectively replicates hearing loss secondary to bacterial meningitis.
• Prolonged meningitis duration increases the risk and severity of hearing loss.
• The cochlear aqueduct serves as a potential pathway for infection spread to the cochlea, impacting hearing.