Correlating the cochleovestibular deficits with tumor size of acoustic neuroma.

CONCLUSION: The tumor size of acoustic neuroma correlates with cochleovestibular deficits. Those tumors with global frequency hearing loss, bilateral gaze nystagmus, or absent caloric and VEMP responses may indicate a tumor size >2.5 cm.

OBJECTIVE: This study aimed to investigate the correlation between cochleovestibular deficits and the size of acoustic neuroma.

PATIENTS AND METHODS: A total of 44 patients with acoustic neuroma were enrolled in this study. Pure tone audiometry, electronystagmography, caloric test, vestibular evoked myogenic potential (VEMP) test, and MRI were conducted.

RESULTS: There is a trend of correlation between tumor size and audiographic configuration, with small-sized tumor in normal and rising types, medium-sized tumor in mid- and high-frequency hearing loss, and large-sized tumor in flat and deafness types. Five patients with bilateral gaze nystagmus had significantly larger tumor size than those without nystagmus. When 1 and 0 are used to represent abnormal and normal responses, respectively, the relationship between tumor size and vestibular function can be expressed as: tumor size (cm)=1.43 (caloric response)+1.35 (VEMP response), indicating that the estimated tumor size for those with abnormal caloric or VEMP responses increased by 1.43 or 1.35 cm, respectively.