Persistent trigeminal artery: a cross-sectional study based on over 3 years conventional angiography, CT angiography and MR angiography images.

Purpose: The trigeminal artery is one of the four primitive anastomosis established between the internal carotid artery and the vertebrobasilar system that regresses at the sixth week of embryonic development. Its persistence in adult life (PTA) is usually found incidentally. The aim of this study is to determine its prevalence, main characteristics and clinical significance.

Methods: A cross-sectional study was performed over the last 3 years, 2012-2014, to analyze images performed on conventional angiography, CT angiography and MR angiography of patients who attended the Neuroradiology Department of the Hospital Universitario Doce de Octubre in Madrid, Spain, to control their underlying pathology.

Results: Nine cases of PTA were found (prevalence 0.37 %, two men, seven women; three right, six left; age range 13-88 years). Eight PTA emerged from the cavernous ICA and one from the petrous segment. Six cases were lateral or petrosal type and one was medial or sphenoidal type. The whole PTAs anastomosed the BA, six at the middle third and three at the distal third. Weon et al.'s type 3 was predominant. CVD incidence was 55.6 % and aneurysm incidence was 22 %.

Conclusions: PTA prevalence was similar to those previously reported, being commonly left-sided, Salas et al.'s lateral or petrosal type, Weon et al.'s type 3 and with no gender predominance. CVD and aneurysms incidence in the presence of a PTA were higher than in general population. Its anatomical relations make it essential to consider its presence and directional blood flow when planning endovascular and neurosurgical treatments.