Posterior circulation infarction
Posterior circulation infarction (POCI), also referred as posterior circulation stroke, corresponds to any infarction occurring within the vertebrobasilar vascular territory, which includes the brainstem, cerebellum, midbrain, thalami, and areas of temporal and occipital lobes.
Please, refer to each specific article for a more precise discussion on the subject:
- posterior cerebral artery (PCA) infarct
- brainstem infarct
- cerebellar infarction
- thalamic infarct
- occipital lobe infarct
Posterior circulation infarctions correspond to around 20% of all ischaemic strokes 1,2.
Symptoms and the clinical syndromes are related to each common site of arterial blood flow occlusion. Common symptoms and signs include dizziness/vertigo, dysarthria, dysphagia, unilateral limb weakness, ataxia, gaze palsy / diplopia, and/or visual field deficits. Less than 1% of patients present with one symptom 4.
It is important to emphasise that the face arm speech test (FAST), a prehospital stroke screening tool, is less sensitive in posterior circulation infarctions and it may be one cause of delay on the diagnosis 1.
Both the anterior and posterior circulation have embolism from the heart, aorta, and proximal arteries as the main cause of infarction. These two systems share the same vascular coats and are under the same arterial pressures 3.
When comparing the amount of blood carried by each system, ~40% of brain blood flow goes into each ICA (totalising ~80% of brain blood flow provided by the anterior circulation) and only 20% into the vertebrobasilar system. So, just by chance we could expect around 1/5th of cardiac origin emboli going to the posterior circulation 3.
Other causes are arterial stenosis, in situ thrombosis, and vertebral artery dissection (this one especially in young patients) 1.
CT, which is the main brain imaging modality in hyperacute stroke, unfortunately, has a known limited sensitivity to assess strokes involving the posterior circulation, especially in the posterior fossa structures 1-3.
Treatment and prognosis
Patients with anterior and posterior circulation disease should be treated in the same way 3.
- 1. Nouh A, Remke J, Ruland S. Ischemic posterior circulation stroke: a review of anatomy, clinical presentations, diagnosis, and current management. Front Neurol. 2014;5: 30. doi:10.3389/fneur.2014.00030 - Free text at pubmed - Pubmed citation
- 2. Merwick Á, Werring D. Posterior circulation ischaemic stroke. BMJ. 2014;348 (may19 33): g3175. doi:10.1136/bmj.g3175 - Pubmed citation
- 3. Caplan L, Chung CS, Wityk R et-al. New England medical center posterior circulation stroke registry: I. Methods, data base, distribution of brain lesions, stroke mechanisms, and outcomes. J Clin Neurol. 2005;1 (1): 14-30. doi:10.3988/jcn.2005.1.1.14 - Free text at pubmed - Pubmed citation
- 4. Savitz SI, Caplan LR. Vertebrobasilar disease. N. Engl. J. Med. 2005;352 (25): 2618-26. doi:10.1056/NEJMra041544 - Pubmed citation