Pourfour du Petit syndrome: a case following a traffic accident with severe cranioencephalic trauma.

Poufour du Petit syndrome is an extraordinarily unusual clinical condition produced by hyperactivity of the sympathetic cervical chain as a consequence of irritation of these nerves. It causes an ipsilateral mydriasis, which, in patients suffering a head injury as in the case reported here, can confuse the diagnosis and disconcert physicians.