Acute basilar artery occlusion
Updates to Article Attributes
Acute occlusion of the basilar artery may cause brainstem or thalamic ischaemia or infarction. It is a true neurointerventialneuro-interventional emergency and, if not treated early, brainstem infarction results in rapid deterioration in conscious level of consciousness and ultimately death.
Epidemiology
Occlusions of the posterior circulation arteries are related to a fifth of all strokes, and basilar artery occlusion is rare ( ~1% of all strokes) 9.
Clinical presentation
Patients with acute occlusion of the basilar artery will present with sudden and dramatic neurological impairment, the exact characteristics of which will depend on the site of occlusion:
- sudden death/loss of consciousness
-
top of the basilar syndrome
- visual and oculomotor deficits
- behavioural abnormalities
- somnolence, hallucinations and dreamlike behaviour
- motor dysfunction is often absent
- proximal and mid portions of the basilar artery (pons) can result in patients being 'locked in' 7-8
- complete loss of movement (quadriparesis and lower cranial dysfunction)
- preserved consciousness
- preserved ocular movements (often only vertical gaze) 8
Pathology
Acute occlusion of the basilar artery can be due to either thromboembolism (e.g. top of the basilar syndrome) or thrombosis due to atherosclerosis or propagation of intracranial dissection.
Radiographic features
Angiography (DSA)
It remains as theRemains the gold standard for the diagnosis of basilar artery occlusion diagnosis, however DSA is used only after non-invasive imaging for therapeutic recanalisation 9 (see case 1). Images demonstrate a filling defect within the vessel.
US
- transcranial Doppler:
- absence of signal in the basilar artery
- indirect signs such as abnormal waveforms in the vertebral arteries and collateral flow
CT
- non-contrast CT
- hyperdense basilar artery (the basilar artery equivalent of the hyperdense MCA sign), present in ~ 65% 9. A high index of suspicion is needed in the correct clinical setting as the diagnosis can easily be missed (often only present on 1 or 2 slices). Additionally it is well recognised that acute clots are of lower attenuation than chronic clots 5-6.
- hypoattenuation delineates tissue with ischaemic damage (limitations due beam-hardening artifacts limit the visualization of the brainstem on CT)
-
contrasted CTcontrast CT- CTA: filling defect within the vessel
- CT perfusion: distinguish penumbra area from
aan irreversibly damaged area (core)
MRI
- loss of flow void
onwithin the basilar artery on spin-echo and FLAIR images -
DWI:
restrictsrestricted diffusionof protonswithin infarcted tissue -
FLAIR/T2: hyperintense signal
(final infarct)within infarcted tissue
Treatment and prognosis
Acute occlusion of the basilar artery is a life threatening event, which carries a terrible prognosis: ~ 90% mortality depending on the location, and high morbidity in the survivors 3.
Treatment usually involves catheter-directed intra-arterial thrombolysis and intravenous heparin, which carries a risk of haemorrhage of up to 15%. Mechanical embolectomy with a clot retrieval device has been used in selected cases.
-<p><strong>Acute occlusion of the basilar artery</strong> may cause brainstem or thalamic ischaemia or infarction. It is a true neurointervential emergency and, if not treated early, brainstem infarction results in rapid deterioration in conscious level and death.</p><h4>Epidemiology </h4><p>Occlusions of the posterior circulation arteries are related to a fifth of all strokes, and basilar artery occlusion is rare ( ~1% of all strokes) <sup>9</sup>. </p><h4>Clinical presentation</h4><p>Patients with acute occlusion of the <a href="/articles/basilar-artery">basilar artery</a> will present with sudden and dramatic neurological impairment, the exact characteristics of which will depend on the site of occlusion:</p><ul>- +<p><strong>Acute occlusion of the basilar artery</strong> may cause brainstem or thalamic ischaemia or infarction. It is a true neuro-interventional emergency and, if not treated early, brainstem infarction results in rapid deterioration in level of consciousness and ultimately death.</p><h4>Epidemiology </h4><p>Occlusions of the posterior circulation arteries are related to a fifth of all strokes, and basilar artery occlusion is rare ( ~1% of all strokes) <sup>9</sup>. </p><h4>Clinical presentation</h4><p>Patients with acute occlusion of the <a href="/articles/basilar-artery">basilar artery</a> will present with sudden and dramatic neurological impairment, the exact characteristics of which will depend on the site of occlusion:</p><ul>
-<li>preserved ocular movements (often only vertical gaze) <sup>8</sup>- +<li>preserved ocular movements (often only vertical gaze) <sup>8</sup>
-</ul><h4>Pathology</h4><p>Acute occlusion of the basilar artery can be due to either thromboembolism (e.g. <a href="/articles/top-of-the-basilar-syndrome">top of the basilar syndrome</a>) or thrombosis due to <a href="/articles/arteriosclerosis-hypertension">atherosclerosis</a> or propagation of <a href="/articles/intracranial-dissection">intracranial dissection</a>. </p><h4>Radiographic features</h4><h5>Angiography (DSA)</h5><p>It remains as the gold standard for basilar artery occlusion diagnosis, however DSA is used only after non-invasive imaging for therapeutic recanalisation <sup>9 </sup>(see case 1). Images demonstrate filling defect within the vessel.</p><h5>US</h5><ul><li>transcranial Doppler:<ul>- +</ul><h4>Pathology</h4><p>Acute occlusion of the basilar artery can be due to either thromboembolism (e.g. <a href="/articles/top-of-the-basilar-syndrome">top of the basilar syndrome</a>) or thrombosis due to <a href="/articles/arteriosclerosis-hypertension">atherosclerosis</a> or propagation of <a href="/articles/intracranial-dissection">intracranial dissection</a>. </p><h4>Radiographic features</h4><h5>Angiography (DSA)</h5><p>Remains the gold standard for the diagnosis of basilar artery occlusion, however DSA is used only after non-invasive imaging for therapeutic recanalisation <sup>9 </sup>(see case 1). Images demonstrate a filling defect within the vessel.</p><h5>US</h5><ul><li>transcranial Doppler:<ul>
-<li>contrasted CT <ul>- +<li>contrast CT <ul>
-<li>CT perfusion: distinguish penumbra area from a irreversibly damaged area (core)</li>- +<li>CT perfusion: distinguish penumbra area from an irreversibly damaged area (core)</li>
-<li>loss of flow void on spin-echo and FLAIR images </li>- +<li>loss of flow void within the basilar artery on spin-echo and FLAIR images </li>
-<strong>DWI</strong>: restricts diffusion of protons</li>- +<strong>DWI</strong>: restricted diffusion within infarcted tissue</li>
-<strong>FLAIR/T2</strong>: hyperintense signal (final infarct)</li>- +<strong>FLAIR/T2</strong>: hyperintense signal within infarcted tissue</li>
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