Four Cases of Carotid-Basilar Anastomosis Associated With Central Nervous System Dysfunction

Various anomalous anastomoses between the carotid and basilar arteries have been reported. Krayenbuhl and Yasargil (1957) classify three types. The first and by far the most frequent type is a persistent primitive trigeminal artery. The second in frequency is a persistent hypoglossal artery. The third type is a persistent primitive acoustic artery. We have found only the first type in our angiographic review. Persistence of the primitive trigeminal artery was first reported by Quain (1844). The first report of angiographic demonstration was not until 1950 (Sutton). In a review of the literature in 1960 (Jackson and Garza-Mercado), only 33 case reports were found. Krayenbuhl and Yasargil in their book on angiography describe four cases demonstrated by angiography. Their first case may be an anomaly other than a persistent trigeminal artery, since the vessel appears to originate at the junction of the C1 to C2 portion of the carotid artery. The vessel illustrated in their last case, described in a discussion of an arteriovenous malformation, may be a branch of the external carotid artery. Lindgren (1954) also reproduced angiograms of two cases. The incidence of this lesion reported in the litera-ture has varied from 1 % to 0-001 % (Jackson and Garza-Mercado, 1960). As pointed out by Harrison and Luttrell (1953), the true incidence of this lesion is very difficult or impossible to ascertain. We found an incidence of approximately 01 % at the Indiana University Medical Center, and in a series of 76 angiograms at the New Castle State Hospital, three cases were demonstrated for an incidence of 4%.