Correlation of hearing loss and radiologic dimensions of vestibular schwannomas (acoustic neuromas)

A retrospective analysis was performed of pure-tone audiograms, speech-discrimination scores, and gadolinium-enhanced magnetic resonance imaging scans of 75 patients with vestibular schwannomas (acoustic neuroma). Sensorineural hearing loss was analyzed for low frequencies (250-500 Hz), midfrequencies (1,000-2,000 Hz), and high frequencies (4,000-8,000 Hz). The largest tumor diameter in the cerebellopontine angle and the lateral extent of invasion by tumor into the internal auditory canal were calculated from magnetic resonance images. There were statistically significant correlations between the largest tumor diameter and the severity of low-frequency sensorineural heaing loss (p = 0.001). However, no significant correlations were found between the following: largest tumor diameter and the severity of mid-frequency or high-frequency sensorineural hearing loss or speech-discrimination scores and lateral extent of invasion of the internal auditory canal and sensorineural hearing loss at all frequencies or speech-discrimination scores (p greater than or equal to 0.05). The findings suggest that nerve compression is not the only cause of hearing loss in vestibular schwannoma.