Tuberculous meningitis-induced unilateral sensorineural hearing loss: a temporal bone study

Area of Science:

• Otolaryngology
• Neurology
• Infectious Diseases

Background:

• The link between meningitis and sensorineural hearing loss (SNHL) is established, particularly for bacterial meningitis.
• Pathophysiology of SNHL in tuberculous meningitis remains poorly understood.

Observation:

• A temporal bone study of a 22-year-old patient with tuberculous meningitis and unilateral SNHL was conducted.
• Histopathology revealed inflammation in the internal auditory canal, modiolus, and Rosenthal's canal, extending to the osseous spiral ligament.
• Severe degeneration of the organ of Corti, cochlear nerve, and spiral ganglion cells was noted, primarily in the basal and middle cochlear turns.

Findings:

• Inflammation predominantly affected the modiolus and internal auditory canal, suggesting these as primary routes of inner ear infection.
• The contralateral ear showed no inner ear inflammation but had middle ear granulomas.
• Damage to neural and sensory structures indicates a retrocochlear component to the hearing loss.

Implications:

• The modiolus and cochlear aqueduct are identified as key pathways for tuberculous meningitis to affect the inner ear.
• The hearing loss progression mirrors that seen in bacterial meningitis, highlighting similarities in SNHL mechanisms.
• Findings contribute to understanding SNHL in tuberculous meningitis and inform potential diagnostic and therapeutic strategies.