Acute basilar artery occlusion

Acute occlusion of the basilar artery may cause brainstem or thalamic ischemia or infarction. It is a true neuro-interventional emergency and, if not treated early, brainstem infarction results in rapid deterioration in the level of consciousness and ultimately death. It is one of the posterior circulation infarctions.

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.

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
    • behavioral abnormalities
    • somnolence, hallucinations and dream-like behavior
    • 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

Acute occlusion of the basilar artery can be due to either thromboembolism,  atherosclerosis or propagation of intracranial dissection. Although these may occur anywhere, each of these have predilections for different segments of the basilar artery:

  • vertebrobasilar junction
    • thromboembolism (e.g. cardioembolic)
    • atherosclerosis with thrombosis
    • propagation of vertebral arterial dissection (rare)
  • midsegment
    • atherosclerosis with thrombosis
  • distal third or basilar tip

Remains the gold standard for the diagnosis of basilar artery occlusion. However, DSA is used only after non-invasive imaging for therapeutic recanalization 9 (see case 1). Images demonstrate a filling defect within the vessel.

  • transcranial Doppler
    • absence of signal in the basilar artery
    • indirect signs such as abnormal waveforms in the vertebral arteries and collateral flow
  • 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 recognized that acute clots are of lower attenuation than chronic clots 5-6
    • hypoattenuation delineates tissue with ischemic damage (limitations due beam-hardening artifacts limit the visualization of the brainstem on CT)
  • contrast CT
  • loss of flow void within the basilar artery on spin-echo and FLAIR images
  • DWI: restricted diffusion within infarcted tissue
  • FLAIR/T2: hyperintense signal within infarcted tissue

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 hemorrhage of up to 15%. Mechanical embolectomy with a clot retrieval device has been used in selected cases.

Stroke and intracranial haemorrhage

Article information

rID: 971
Synonyms or Alternate Spellings:
  • Basilar artery occlusion
  • Thrombosis of basilar artery
  • Thrombosis of the basilar artery
  • Basilar arterial thrombosis
  • Basilar artery thrombosis

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Cases and figures

  • Figure 1: vascular territories
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  • Case 1: hyperdense artery
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  • Case 2: endovascular clot retrieval
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  • Case 3: infarct
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  • Case 4
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  • Case 5
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  • Case 6
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  • Case 7
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  • Case 8
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  • Case 9
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  • Case 10
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