Quint D J, Silbergleit R, Young W C
Department of Radiology, University of Michigan Hospitals, Ann Arbor 48109-0030.
Radiology. 1992 Feb;182(2):477-81. doi: 10.1148/radiology.182.2.1732967.
Congenital absence of one or both internal carotid arteries (ICAs) has a high association with circle of Willis aneurysm formation. Since the carotid canals in the skull base form secondary to the presence of the embryonic ICA, absence or hypoplasia of a carotid canal on a computed tomographic (CT) scan through the skull base should suggest a congenital ICA abnormality and prompt a search for associated intracranial vascular abnormalities. Of four patients with carotid canal underdevelopment evident at CT, two had associated circle of Willis aneurysms and a third had an extensive skull base rete mirabile supplying an abnormal tangle of vessels in the basal cisterns. Only two patients (one with an aneurysm, one with the skull base rete mirabile) presented with subarachnoid hemorrhage. One patient presented with monocular decreasing vision due to an enlarging aneurysm, and one patient was essentially asymptomatic. If asymmetry or absence of the carotid canals is evident on CT scans of the head, further evaluation to rule out a potentially life-threatening intracranial vascular abnormality such as those found in these patients should be seriously considered, even in a young or asymptomatic patient.
一侧或双侧颈内动脉先天性缺如与 Willis 环动脉瘤形成高度相关。由于颅底的颈动脉管继发于胚胎期颈内动脉的存在而形成，因此通过颅底的计算机断层扫描（CT）显示颈动脉管缺如或发育不全应提示先天性颈内动脉异常，并促使进一步检查是否存在相关的颅内血管异常。在 CT 上显示颈动脉管发育不全的 4 例患者中，2 例伴有 Willis 环动脉瘤，第 3 例有广泛的颅底奇异网，为脑基底池内异常的血管团供血。仅 2 例患者（1 例有动脉瘤，1 例有颅底奇异网）出现蛛网膜下腔出血。1 例患者因动脉瘤增大出现单眼视力下降，1 例患者基本无症状。如果头部 CT 扫描显示颈动脉管不对称或缺如，即使是年轻或无症状患者，也应认真考虑进一步评估以排除这些患者中发现的潜在危及生命的颅内血管异常。
