I thank Drs Norris and Beletsky for their comments and for sharing some data from their ongoing prospective study of cervical artery dissection (CAD). It is, of course, possible that the association of dissection with preceding varicella-zoster virus infection is coincidental1; however, several facts make it reasonable to postulate that a constellation of predisposing factors acting in synergy lead to CAD. First, it is precisely the fact that a substantial proportion of patients have only minor trauma such as sneezing and coughing, highly frequent phenomena, that suggests that a certain predisposition is required. Second, anatomical abnormalities of blood vessels, including redundancy,2 fibromuscular dysplasia, and inherited connective tissue diseases,3 increase the risk of dissection. Disruption of the internal elastic lamina is a shared feature of dissected arteries4 and varicella-zoster virus vasculitis.5 Implicating such changes in facilitating an arterial dissection, probably in combination with trauma, is plausible. Third, additional predisposing factors may be involved. For example, there is a seasonal pattern of spontaneous CAD that suggests environmental influences.6 Last, attributing the role of infection solely to the coughing and vomiting induced by it does not explain the occurrence of dissection after varicella-zoster infection, which did not cause such symptoms.
Constantinescu CS. Carotid Dissection and Viral Illness—Reply. Arch Neurol. 2000;57(11):1659. doi: