Persistent primitive trigeminal artery: analysis of anatomical characteristics and clinical significances

The purpose of this study was to evaluate the classification of persistent primitive trigeminal artery (PPTA) based on computed tomography (CT) angiography, magnetic resonance (MR) angiography, and cerebral angiography and to review the clinical significance.

Images obtained by CT angiography performed between January 2011 and August 2013, MR angiography between January 2005 and January 2013, and cerebral angiography between January 2003 and November 2012 were analyzed for the presence of a PPTA. The diagnostic criterion for a PPTA was an artery that arises from the cavernous internal carotid artery and then joins the basilar artery (BA). We classified each PPTA by two different methods. First, the PPTA was classified as type 1, 2, 3, or 4 according to Weon et al.'s classification. Second, the classification of the PPTA was also made according to Salas et al.'s proposal, as a medial or lateral type.

Eighteen of 8,900 patients (0.2%) had a PPTA. Of all 18 patients with a PPTA, nine were classified as type 1, two as type 2, six as type 3, and one as type 4. Seventeen PPTAs were a lateral type, and one was a medial type. Regarding the degree of BA hypoplasia, no hypoplasia was seen in six cases, moderate hypoplasia was identified in six cases, and severe hypoplasia was seen in six cases.

This study revealed four types of PPTA according to Weon et al.'s classification. The presence of a PPTA should be considered by both the clinician and the radiologist who interprets the CT angiography, MR angiography, and conventional angiograms.