An Unusually Benign Course of Extensive Posterior Circulation Occlusion

Acute basilar artery occlusion is associated with poor outcome. In a few cases, occlusion occurs over a period allowing adequate collateral circulation to the posterior fossa. We describe a rare presentation with transient loss of consciousness (LOC) in a patient with extensive occlusion of the posterior circulation.

Case report.

We describe a 70-year-old right-handed man with a history significant for atrial fibrillation and dolichoectasia of the basilar artery. Fourteen years ago, he had a small infarction in the pons resulting in right hemiparesis. Magnetic resonance angiogram at that time showed mild intracranial atherosclerosis. He was treated with warfarin for secondary stroke prevention. He presented to our emergency department after a witnessed spell of LOC after a large meal. On regaining consciousness, he had 2 episodes of emesis. Examination revealed only a spastic right hemiparesis from the old stroke in the pons. Cerebral angiogram showed absent flow in the mid and distal basilar arteries, both posterior cerebral arteries, and both posterior communicating arteries with bilateral stenoses of internal carotid arteries. His international normalized ratio in the emergency department was 1.1. He was treated with intravenous heparin and did well. Three months later, he underwent stent treatment of the worsening stenosis (90%) of the right internal carotid artery.

Occasionally, collateral circulation has the potential to maintain adequate perfusion to the posterior fossa in severe cases of posterior circulation occlusion and diffuse intracranial atherosclerotic disease. Careful patient selection is essential before planning any endovascular intervention.