The prevalence and clinical course of patients with 'incidental' acoustic neuromas

Conclusions. This study suggests that among patients diagnosed with 'incidental' acoustic neuromas ( ANs), a substantial portion are discovered incidentally. Small and medium-sized ANs that are found incidentally may have a more benign nature, and may be less likely to require interventions. Objective. To estimate the prevalence of ANs, and to compare the prognosis and progression of the disease between those diagnosed incidentally verse symptomatically with an AN. Patients and methods. This was a retrospective evidence-based case series of patients with AN treated at a tertiary medical center between November 1999 and January 2005. An MRI with gadolinium was performed on all patients to establish the diagnosis of AN. A medical chart review of these patients was searched for sex distribution, age, presenting symptoms, hearing loss, speech discrimination scores, tumor characteristics by imaging, intervention performed, and time between diagnosis and intervention. The studied population was divided into those patients with pre-imaging audiovestibular symptoms provoking a clinical suspicion of AN ( symptomatic group) and those without a pre-imaging suspicion of AN ( incidental group). Results. The charts of 120 patients with ANs were analyzed and categorized as either incidentally or symptomatically discovered. Incidentally discovered ANs accounted for 12% of patients with the diagnosis of AN in our population. The average age at diagnosis was 55.7 and 52.8 years ( p = 0.50) in the symptomatic and incidental groups, respectively. The gender distribution was not different between the groups ( p = 0.08). Audiometry revealed a speech discrimination score asymmetry greater in the symptomatic group ( p < 0.0001). Tumor size by imaging performed at diagnosis in the incidental population was 1.09 cm on average, compared with 1.5 cm in the symptomatic patients ( p = 0.08). A greater proportion of patients with symptomatically discovered AN underwent intervention by surgical resection, stereotactic radiosurgery, or radiation compared with patients with incidentally discovered AN ( 76% versus 47%, p = 0.02).