Magnetic resonance angiographic study of the variations in the branching pattern of external carotid artery

Knowledge of anatomy of the branching pattern of external carotid artery (ECA) is needed for head and neck surgeries and diagnostic purposes. Previously knowledge regarding this was obtained from dissecting specimens. But with magnetic resonance angiograms being done widely, data from these may be taken for a better understanding of the branching pattern of ECA. To study the branching pattern of external carotid artery using MR angiograms taken for other purposes. A cross-sectional study was carried out in our institution, which is a tertiary care centre, between September 2013 and September 2015 in which we studied the MR angiograms of 50 patients. Out of the 50 MR angiograms studied, variations were seen in 5 cases. In two cases, the ascending pharyngeal artery was seen to arise from the lateral side instead of the medial side on the left side. In another two, the ascending pharyngeal artery was seen to arise from the occipital artery on the left side. In one case the superior laryngeal artery arose from the external carotid artery. MR angiogram taken for other purposes is an inexpensive, ionizing radiation free method which can be used to study the branching pattern of external carotid artery.

Variant ascending pharyngeal artery maintaining flow in a subocclusive internal carotid artery

Ectopic branches of the external carotid artery are rare but have critical diagnostic and therapeutic implications. We present a case involving a 70-year-old man who presented with recurrent left hemispheric strokes in the setting of a subocclusive left internal carotid stenosis. A left ascending pharyngeal artery with variant origin from the internal carotid artery helped maintain flow distal to the area of stenosis and allowed for safe and successful internal carotid artery stenting. Identification of this variant and recognition of the anastomotic network involving this connection were crucial to determine the safety of stenting. The patient had no further recurrent events and had sustained improvement on his 90-day follow-up.