Relationships between imaging characteristics and hearing levels in patients with vestibular schwannomas treated by stereotactic radiosurgery

Background

This study aimed to investigate the correlation between the imaging characteristics and audiological features in patients with vestibular schwannomas and to analyze hearing outcomes following stereotactic radiosurgery.

Methods

This was a retrospective study of 100 patients who underwent stereotactic radiosurgery for vestibular schwannomas between January 2002 and January 2012. The demographic data, clinical presentation, imaging characteristics, pure-tone audiogram, speech discrimination, stapedial reflex, auditory brainstem response, oculomotor control, caloric test, and hearing outcome following radiosurgery were reviewed. Image characteristics, including tumor size and location, fundus involvement, brainstem compression, and internal auditory canal (IAC) dilatation, were studied.

Results

Tumors were classified by their location as extracanalicular (8%), intracanalicular (19%), and intracanalicular and extracanalicular (73%). Tumors may be localized, without occupying the fundus of the IAC (63%), or they may extend to the fundus (37%). Dilatation of IAC was noted in 82 cases (82%). The tumors were in contact with the brainstem in 15 cases (15%); the brainstem was compressed by the tumors in 45 cases (45%). Abnormalities in the stapedial reflex, oculomotor control, and caloric tests were not significantly associated with tumor size. Tumor size was positively correlated with the pure-tone average (PTA; p = 0.0005), and there was a significant correlation between fundus involvement and deterioration of the PTA (p = 0.0073). The other imaging characteristics analyzed were not associated with hearing loss. The wave I-V interaural latency difference was significantly affected in patients with larger tumors. Our study showed an accelerated rate of deterioration of the serial PTA in the first 3 years, followed by a more gradual decline.

Conclusions

Imaging characteristics, including fundus involvement and tumor size, are correlated with the PTA before radiosurgery and are not associated with hearing preservation following radiosurgery. An accelerated rate of hearing loss in the first 3 years after radiosurgery was observed.

Clinical trial identification

Legal entity responsible for the study

China Medical University Hospital

Funding

China Medical University

Disclosure

All authors have declared no conflicts of interest.