A 19-year-old man was admitted to the emergency department for sudden onset of headache, right hemiparesis and dysarthria during sexual activity. Anisocoria was also present at neurological examination. Subarachnoid haemorrhage (SAH) was suspected and a CT scan was performed.
The unenhanced CT scan excluded SAH and revealed the presence of a hyperdensity of the distal segment of the basilar artery (Fig. 1). For further definition a CT angiography was performed. CT angiography showed a filling defect of 7 mm within the distal segment of the basilar artery (Fig. 2), consistent with acute thrombosis. Angiography confirmed the presence of the filling defect within the basilar artery (Fig. 3). Thromboaspiration through an aspiration pump was performed and a large thrombus was removed (Fig. 4). Final angiography showed complete recanalisation of the basilar artery (Fig. 5). Brain MRI, performed ten days later, showed subacute ischaemic lesions in the pons and in both cerebellar hemispheres (Fig. 6). During hospitalisation the patient underwent ultrasonography of the lower extremity veins and transoesophageal ecochardiography, and deep vein thrombosis of the right leg and patent foramen ovale (PFO) were found. In addition, blood tests revealed the presence of lupus anticoagulant. The young patient recovered well and was discharged after two weeks of hospitalisation.
Basilar artery occlusion (BAO) is a rare event, accounting for about 1% of all strokes, associated with high mortality and morbidity . The most frequent causes of BAO are atherosclerotic occlusions resulting from local thrombosis due to severe stenosis and embolic occlusions from cardiac and large artery sources. Rare causes of BAO include arteritis and dissections . A PFO is a highly prevalent finding in cryptogenic ischaemic strokes, particularly in young adults. A PFO is postulated to serve as a conduit for paradoxical embolism to the brain from deep vein thrombosis . Clinical symptoms and signs depend on the location of occlusion in the basilar artery and on the anatomical regions affected by the resulting ischaemia. Occlusions of the proximal or middle segments of the basilar artery usually result in large pontine strokes with either hemiplegia or quadriplegia; other symptoms include reduced consciousness, dysarthria and dysphagia. Occlusions in the distal segment of the basilar artery cause stroke bilaterally in the mesencephalon and thalamus with decreased consciousness, quadriparesis, and nuclear or supranuclear oculomotor and pupillomotor dysfunctions . A hyperdense basilar artery sign at unenhanced CT, representing acute thrombus or clot within the vessel, is seen in 50-70% of patients with basilar artery thrombosis. CT angiography is a useful method in the diagnosis of BAO in the acute setting, allowing demonstration of a filling defect within the vessel . CT has a low sensitivity for early parenchymal ischaemia, due to significant artifacts caused by the bony structures surrounding the brain stem and cerebellum. MRI is superior to CT in detection of early ischaemia, notably through demonstration of restricted diffusion using diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps . Treatment options include intravenous thrombolysis and endovascular recanalisation techniques (mechanical thrombectomy with stent retriever or thromboaspiration). Written informed patient consent for publication has been obtained.
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