Familial occurrence of spontaneous dissection of the internal carotid artery.

Spontaneous dissections of the extracranial internal carotid artery are diagnosed more frequently as their clinical and angiographic features are more widely recognized. Familial occurrence of spontaneous dissection of the internal carotid artery has not been previously reported. We describe the occurrence of this entity in a mother and daughter and also in a father and son. The familial occurrence of spontaneous dissection of the internal carotid artery raised the possibility of an inherited disorder of the blood vessel wall that predisposes the artery to this disorder. Fibromuscular dysplasia is suspected to be the underlying arterial disease, but other unknown arteriopathies cannot be excluded.