To the Editor.—
As noted by Vijayan and Dreyfus in their recent, excellent report, "Posttraumatic Dysautonomic Cephalalgia: Clinical Observations and Treatment" (Arch Neurol 32:649, 1975), paroxysmal, unilateral, vascular headache (migraine) may have its onset following trauma, independent of the site of injury.1Because of the association of injury site and dysautonomic changes among their five patients, a cause and effect relationship is assumed. That the vascular headache is secondary to third-order neuronal injury is also an assumption.It should be noted that the negative results from the sweat test and positive results from the pupillary function tests correctly place the lesion in the pericarotid sympathetic plexus, which anatomically begins superior to the hyoid cartilage. As described by the authors, possibly one (case 1) of the five patients was injured in this area. In fact, injury in two patients (cases 3 and 5) is due to a "whiplash" injury. By