Epidemiology and Environmental Risk Factors Associated with Vestibular Schwannoma.

OBJECTIVE: Vestibular schwannomas (VS) are tumors originating from the eighth cranial nerve. The etiology and environmental risk factors for VS remain unclear. The goal of this study was to explore some potential environmental risk factors associated with vestibular schwannoma (VS). METHODS: A hospital-based case-control study with 1:1 matching based on age and sex was designed. A written questionnaire was administered. Multiple conditional logistic regression models were created to determine odds ratio (OR). RESULTS: There were 353 matched pairs with an average age at diagnosis of 53 years (SD ± 12), 50% of participants were female, and >90% were white. Multivariate models revealed significantly increased OR with a history of hay fever (OR = 3.91, 95% confidence interval [CI] = 1.35-11.30) and managerial/professional occupations (OR = 4.41, 95% CI = 2.07-9.40). Tobacco use had a decreased association with VS (<20 pack-years OR = 0.10, 95% CI = 0.04-0.28; ≥ 20 pack-years OR = 0.03, 95% CI = 0.01-0.12). CONCLUSIONS: The profile of patients with VS includes white race, age 50-60 years, either sex, and working in a professional occupation. Better access to health care and diagnostic imaging likely plays a role in the diagnosis of this tumor. Hay fever is strongly associated with VS. Tobacco use demonstrates an inverse relationship with VS, but the possible biologic mechanism for this is poorly understood, and tobacco remains a significant public health problem.

Clinical evaluation of CyberKnife in the treatment of vestibular schwannomas.

OBJECTIVE: This study assessed the posttreatment tumor control and auditory function of vestibular schwannoma (VS) patients after CyberKnife (CK) and analyzed the possible prognostic factors of hearing loss. METHODS: We retrospectively studied 117 VS patients, with Gardner-Robertson (GR) classification grades I to IV, who underwent CK between 2006 and 2012. Data including radiosurgery treatment parameters, pre- and postoperative tumor size, and auditory function were collected and examined. RESULTS: With CK, 117 patients had excellent tumor control rates (99.1%), with a mean imaging followup of 61.1 months. Excluding 52 patients (GR III-IV pretreatment), 53 (81.5%) of the remaining 65 patients (initial GR I-II) maintained GR I or II hearing after CK, with a mean audiometric followup of 64.5 months. Twelve patients experienced hearing degradation (91.6% were GR II pretreatment); they appeared to have significantly larger tumor sizes, significantly smaller cochlear sizes, and higher prescribed cochlear doses, compared to the patients with preserved hearing. CONCLUSION: Our data showed that CK treatment provided an excellent tumor control rate and a comparable hearing preservation rate in VS patients. Patients with pretreatment GR II hearing levels, larger tumor volumes, smaller cochlear sizes, and higher prescribed cochlear doses may have poor hearing prognoses.

Therapeutic profile of single-fraction radiosurgery of vestibular schwannoma: unrelated malignancy predicts tumor control.

Radiosurgery has become an accepted treatment option for vestibular schwannomas. Nevertheless, predictors of tumor control and treatment toxicity in current radiosurgery of vestibular schwannomas are not well understood. To generate new information on predictors of tumor control and cranial nerve toxicity of single-fraction radiosurgery of vestibular schwannomas, we conducted a single-institution long-term observational study of radiosurgery for sporadic vestibular schwannomas. Minimum follow-up was 3 years. Investigated as potential predictors of tumor control and cranial nerve toxicity were treatment technology; tumor resection preceding radiosurgery; tumor size; gender; patient age; history of cancer, vascular disease, or metabolic disease; tumor volume; radiosurgical prescription dose; and isodose line. Three hundred eighty-six patients met inclusion criteria. Treatment failure was observed in 27 patients. History of unrelated cancer (strongest predictor) and prescription dose significantly predicted tumor control. The cumulative incidence of treatment failure was 30% after 6.5 years in patients with unrelated malignancy and 10% after ≥15 years in patients without such cancer (P < .02). Tumor volume was the only predictor of trigeminal neuropathy (observed in 6 patients). No predictor of facial nerve toxicity was found. On the House and Brackmann scale, 1 patient had a permanent one-level drop and 7 a transient drop of 1 to 3 levels. Serviceable hearing was preserved in 75.1%. Tumor hearing before radiosurgery, recurrence, and prescription isodose predicted ototoxicity. Unrelated malignancy is a strong predictor of tumor control. Tumor recurrence predominantly predicts ototoxicity. These findings potentially will aid future clinical decision making in ambiguous cases.

Role of tobacco use in the etiology of acoustic neuroma.

Two previous studies suggest that cigarette smoking reduces acoustic neuroma risk; however, an association between use of snuff tobacco and acoustic neuroma has not been investigated previously. The authors conducted a case-control study in Sweden from 2002 to 2007, in which 451 cases and 710 population-based controls completed questionnaires. Cases and controls were matched on gender, region, and age within 5 years. The authors estimated odds ratios using conditional logistic regression analyses, adjusted for education and tobacco use (snuff use in the smoking analysis and smoking in the snuff analysis). The risk of acoustic neuroma was greatly reduced in male current smokers (odds ratio (OR) = 0.41, 95% confidence interval (CI): 0.23, 0.74) and moderately reduced in female current smokers (OR = 0.70, 95% CI: 0.40, 1.23). In contrast, current snuff use among males was not associated with risk of acoustic neuroma (OR = 0.94, 95% CI: 0.57, 1.55). The authors' findings are consistent with previous reports of lower acoustic neuroma risk among current cigarette smokers than among never smokers. The absence of an association between snuff use and acoustic neuroma suggests that some constituent of tobacco smoke other than nicotine may confer protection against acoustic neuroma.

Long-term control of vestibular schwannoma after a translabyrinthine complete removal.

OBJECTIVE: The goal of this study was to determine the rate of recurrent vestibular schwannoma after a total removal via the translabyrinthine approach. PATIENTS: Between 1973 and 1995, 346 patients were operated on by a translabyrinthine approach. Ninety-one patients were included in a retrospective study for follow-up of 5 years or longer. RESULTS: The mean follow-up period for magnetic resonance imaging (MRI) examination was obtained after mean of 11 years in 91 patients. None of the 91 patients experienced a recurrent vestibular schwannoma on MRI. CONCLUSION: The translabyrinthine approach is a safe procedure for total definitive removal of a vestibular schwannoma and permitted the absence of tumoral recurrence in our series of 91 patients. A single gadolinium-enhanced MRI scan 5 years after surgery is advised in case of total removal. In case of any doubt about the quality of the tumoral removal, a proposed MRI follow-up schedule within 2 years and 5 years of surgery is an initial baseline pattern, and possibly thereafter repeated MRI examinations on clinical grounds.

The burden of screening for acoustic neuroma: asymmetric otological symptoms in the ENT clinic.

The rising numbers of legal cases relating to delay in the diagnosis of acoustic neuroma, combined with the increasing availability of magnetic resonance, is increasing pressure on otologists to make an early definitive diagnosis of cerebellopontine angle tumours. Unilateral or asymmetrical otologic symptoms not explained by external or middle ear disease are elicited in 16.6% of 500 consecutive attenders to an otolaryngology clinic. An agreed policy of risk stratification of patients with unexplained asymmetric otological symptoms is required if expense is to be limited and litigation minimized.