Incidence, seasonality and comorbidity in vestibular neuritis.

Aims of the present study were: (1) to assess the incidence of vestibular neuritis (VN) in the adult population in two cities in Croatia, (2) to identify distribution of new VN cases in the different months and seasons by years, and (3) to identify comorbidities associated with VN. This is a prospective, population-based study conducted in the cities of Zagreb and Velika Gorica, Croatia in the 2011-2012 period. All diagnoses were confirmed either with caloric test or vestibular evoked myogenic potentials within 7 days of symptom onset. Following clinical parameters were collected from all patients: age, gender, side of the lesion, month and season of symptoms onset and comorbidities. We identified 79 new cases of VN (34 in 2011, 45 in 2012). The male to female ratio was 1.1:1. The mean age at the onset of the disease was 52.3 (range 20-86) years. The average annual incidence was 11.7 per 100,000 (95 % CI 7.8-15.6) in the 2011 period and 15.5 per 100,000 (95 % CI 11.0-20.0) in the 2012 period. For both years there was no statistically significant uneven distribution in the different months or seasons by years. The most frequent comorbidities present in VN patients were hypertension (30.4 %), diabetes mellitus (8.9 %), hyperlipidemia (7.5 %) and hypothyreosis (6.3 %). Our study has shown higher incidence of VN than previously reported. We have found no evidence of seasonality of VN and significant proportion of VN patients older than 50 years who had vascular risk factors present.