The internal carotid artery siphon in children and adolescents.

We observed significant lesions of the carotid artery siphon in two young subjects with fatal stroke. Because stroke in children and adolescents is uncommon and poorly understood, we examined the internal carotid artery in the 'siphon' of the skull in 24 unselected, but nearly consecutive autopsies. The age range was 10 days to 38 years, with 11 males and 13 females, six blacks, and 18 whites. In no case was stroke the cause of death. Intimal lesions of two types were found in the carotid siphon of all cases. (1) The first was focal splitting and/or duplication of the internal elastic lamina with variable proliferation of smooth muscle. The resulting 'fibrous' plaques or cushions, when severe, were usually found at natural bends in the artery. The number and severity of this type of lesion increased with age, but there were no differences in severity or distribution when compared by sex, race, or mode of death. (2) The second was internal elastic calcification which was found in all cases older than 9. This was increasingly severe with age. Although the frequency of the vascular lesions was surprisingly high, the relationship of either type to dissecting aneurysm or other stroke lesion remains unclear.