Seasonal pattern of spontaneous cervical artery dissection

Object. The etiology of spontaneous cervical artery dissection is poorly understood; however, it may involve genetic and environmental factors. The purpose of this study was to determine whether seasonality of spontaneous cervical artery dissection exists. Methods. The seasonal pattern of spontaneous cervical artery dissection was analyzed in a group of 200 consecutive patients (104 females and 96 males with a mean age of 44.9 years) who were evaluated using the Rayleigh test during the period from 1970 to 1990. The majority of patients resided in the midwestern section of the United States, where large seasonal fluctuations in climate occur. A circannual periodicity was found in the frequency of spontaneous cervical artery dissections with a peak occurring in October (p < 0.02). The seasonal variation was substantial, with approximately 53% more patients suffering a cervical artery dissection during autumn than during other seasons. Conclusions. A seasonal pattern of' spontaneous cervical artery dissection exists with a peak occurring in October. The cause of the seasonality remains to be explained; however, weather- or infectious disease-related factors may pro vide etiological leads.