Risk factors associated with vestibular nerve schwannomas.

INTRODUCTION: Vestibular nerve schwannoma is a benign tumor that originates in the sheath of Schwann of the eighth cranial nerve. It is considered one of the most common benign intracranial tumors, and its cause is unclear. OBJECTIVE: To identify the risk factors associated with vestibular nerve schwannomas. METHODS: A hospital-based exploratory case-control study was conducted between 2006 and 2010 in 2 municipalities in the northeast region of Brazil. We included individuals with unilateral vestibular nerve schwannomas confirmed by imaging. The controls, selected from the same institutions as the cases, exhibited unilateral hearing loss or tinnitus and had undergone investigatory examinations similar to those of the cases, but the presence of tumor had been excluded. A pretested structured questionnaire, administered by trained interviewers who were blind to the condition of the individual being interviewed, was used to obtain sociodemographic data and data on potential risk factor exposure. We performed a multivariate analysis using unconditional logistic regression. RESULTS: A total of 44 patients with vestibular nerve schwannomas and 104 controls participated in the study. A history of chicken pox (odds ratio, 6.59; 95% confidence interval, 2.07-20.9) and the exposure to more than 1 cranial x-ray procedure (odds ratio, 4.55; 95% confidence interval, 1.10-19.2) were identified as potential risk factors. CONCLUSION: This exploratory study brings new hypotheses to be tested and thus works toward clarifying the causes and mechanisms involved in the cause and development of vestibular nerve schwannoma.