Hyperdense Basilar Artery

Acute thrombosis of the basilar artery either due to primary atheromatous disease in the vessel or from an embolus is a devastating neurological event. The diagnosis of this condition has to be early enough for planning direct therapeutic interventions or for expediting supportive care. Non enhanced computed tomographic scans may show a hyperdense basilar artery (HDBA) sign before a brainstem infarct is visualized. This sign should assist stroke team in diagnosis of basilar artery thrombosis. This holds true especially in the patients with signs of posterior circulation abnormalities.1 In the anterior circulation detection of “hyperdense middle cerebral artery (MCA) sign” has a high specificity for MCA occlusion. The application of similar sign in the posterior circulation is difficult due to inherent limitations of CT in evaluating posterior fossa and lack of conclusive evidence in applying HDBA sign for basilar thrombosis. Isolated studies have shown the benefit of using this sign in suspected cases of brainstem infarction. 1, 2 The pitfalls of CT like beam hardening artefacts in the posterior fossa and dual helical CT of posterior fossa may make the use of this sign unreliable.3 The identification of acute basilar thrombosis early may prompt interventional therapies like direct intra-arterial thrombolysis or mechanical clot retrieval and stenting of vertebral artery dissection when present. The presence of HDBA sign should at least prompt a emergency MR brain +/- MR angiography or a CT angiography of the brain to exclude basilar thrombosis as in the present case.