Bacterial meningitis in adults: demonstration of inner ear involvement using high-resolution MRI

To visualize the sites involved in audiovestibular dysfunction during bacterial meningitis in adults and to relate these findings to the extent of hearing impairment and vestibular dysfunction.

Hearing impairment is among the most frequent complications of bacterial meningitis.

High-resolution MRI (HR-MRI) of the inner ear was performed in seven adult patients with hearing loss as a complication of bacterial meningitis.

Five patients had unilateral (n = 1) or bilateral (n = 4) contrast enhancement of vestibulocochlear structures. The structures most frequently involved were the cochlear nerve (n = 9), the first cochlear turn (n = 9), the vestibulum (n = 9), and the semicircular canals (n = 7). There was a significant correlation between clinical and MRI findings: all nine ears with cochlear enhancement were deaf (hearing loss >90 dB), whereas none of the five ears with normal MRI findings had hearing losses of more than 90 dB (range, 30 to 70 dB; p = 0.0005). Vestibular dysfunction as revealed clinically and by quantitative vestibular function testing was found in six of seven patients (11 of 14 ears). Five of these patients (nine ears) also demonstrated enhancement of the vestibular organ on high-resolution MRI of the inner ear.

High-resolution MRI can visualize the involvement of vestibulocochlear structures in bacterial meningitis in both cooperative and consciously impaired patients. These findings suggest a correlation between abnormalities on MRI and the extent of cochlear dysfunction.