A rare aberrant distal branch preventing complete internal carotid artery occlusion.

A 72-year-old man presented with a 3-day history of recurrent transient ischaemic attacks comprising slurred speech, left arm weakness and paresthesia. Carotid Doppler revealed total occlusion of the right internal carotid artery (ICA). Computed tomography angiography demonstrated occlusion of the proximal right ICA over a length of 1.5 cm. The ICA distal to the occlusion was entirely normal. In view of the normal distal ICA, a decision was made to proceed with surgical exploration and right carotid endarterectomy, on the basis that there must have been some flow through the lesion. Intra-operatively, there was an extensive plaque in the carotid bulb and proximal ICA causing 80-90% stenosis. Fresh thrombus completed the occlusion. An aberrant branch of the ICA was identified distal to the plaque, the backflow through which maintained patency of the distal ICA. A standard endarterectomy was performed. The patient recovered uneventfully, being discharged on the second post-operative day.