Environmental factors and cervical artery dissection.

A history of a minor precipitating event is frequently elicited in patients with a spontaneous dissection of the carotid or vertebral artery. Other precipitating events associated with hyperextension or rotation of the neck include practicing yoga, painting a ceiling, coughing, vomiting, sneezing, the receipt of anesthesia, and the act of resuscitation. Chiropractic manipulation of the neck has been associated with carotid artery dissection and, particularly, vertebral artery dissection. Another risk factor for spontaneous dissections seems to be a recent history of a respiratory tract infection. The possibility of an infectious trigger is supported by the finding of a seasonal variation in the incidence of spontaneous dissections, with a peak incidence in fall. A potential link with common risk factors for vascular disease, such as tobacco use, hypertension, and the use of oral contraceptives, has not been systematically evaluated, but atherosclerosis appears to be distinctly uncommon in patients with a dissection of the carotid or vertebral arteries. In conclusion, although any hypotheses on the pathogenic mechanisms linking environmental factors and dissection remain speculative at present, we believe that these hypotheses may contribute to better define the spectrum of pathogenic conditions predisposing a cervical artery to dissection and provide arguments to better investigate the single or combined effect of such susceptibility factors in future studies.