What are the characteristics of a posterior circulation stroke (Posterior Circulation Infarction)?

From the Guidelines

Patients with suspected posterior circulation stroke should be immediately sent to an emergency department with capacity for advanced stroke care, where urgent brain imaging and non-invasive vascular imaging should be completed as soon as possible within 24 hours. Posterior circulation stroke affects the vertebrobasilar arterial system, which supplies blood to the brainstem, cerebellum, and occipital lobes. The symptoms of posterior circulation stroke can be distinct and include vertigo, ataxia, visual field defects, and cranial nerve abnormalities, making them challenging to diagnose compared to anterior circulation strokes [ 1 ].

Some key points to consider in the management of posterior circulation stroke include:

• Urgent brain imaging (computed tomography (CT) or magnetic resonance imaging (MRI)) and non-invasive vascular imaging (CT angiography (CTA) or MR angiography (MRA) from aortic arch to vertex) should be completed as soon as possible within 24 hours [ 1 ].
• An electrocardiogram (ECG) should be completed without delay [ 1 ].
• Patients who present within 48 hours of a suspected transient ischemic attack (TIA) or nondisabling ischemic stroke with symptoms such as transient, fluctuating, or persistent unilateral weakness, language/speech disturbance, or fluctuating or persistent symptoms without motor weakness or language/speech disturbance are considered at highest risk of first or recurrent stroke [ 1 ].
• Intravenous thrombolysis appears appropriate as first-line therapy for posterior circulation stroke, and alteplase can be given to patients with cervical artery dissection, seizure at onset, and evidence of acute ischemia on brain imaging [ 1 ].

The goal of treatment is to minimize morbidity, mortality, and improve quality of life, and therefore, prompt recognition and management of posterior circulation stroke are crucial. After acute treatment, secondary prevention includes antiplatelet therapy, anticoagulation for patients with atrial fibrillation, high-dose statin therapy, and blood pressure management [ 1 ].

From the Research

Presentation and Diagnosis of Posterior Circulation Stroke

• Posterior circulation stroke presents most commonly with dizziness or vertigo and must be distinguished from more benign diagnoses 2
• Neurologic examination for focal neurologic deficit, dysmetria, dysarthria, ataxia, and truncal ataxia is essential 2
• The HINTS (head impulse, nystagmus, and test of skew) examination can be useful for identifying dizziness presentations concerning for stroke when performed by those with appropriate training 2

Imaging and Diagnostic Techniques

• Contrast tomography (CT), CT angiography, and CT perfusion have limited sensitivity for identifying PC strokes 2
• Magnetic resonance imaging is the gold standard, but it may miss some PC strokes early in their course 2
• Recent advances in imaging of posterior stroke, including diffusion-weighted and diffusion tensor imaging (DWI and DTI), perfusion-weighted imaging (PWI), vascular imaging, and susceptibility weighted imaging (SWI), have improved diagnostic and prognostic capabilities 3

Treatment and Management

• Thrombolysis is recommended in patients presenting within the appropriate time window for thrombolytic therapy 2, 4
• Endovascular therapy, including thrombectomy, may be beneficial for basilar artery and posterior cerebral artery infarcts, but its applicability for all PC strokes remains to be determined 2, 4, 5
• Secondary prevention of posterior circulation strokes includes aggressive treatment of cerebrovascular risk factors with both drugs and lifestyle interventions and short-term dual anti-platelet therapy 4
• Decompressive craniectomy may be beneficial for ischemic and hemorrhagic space-occupying cerebellar strokes 4

Prognosis and Outcomes

• Successful recanalization and shorter time from stroke onset to the start of the procedure are significant predictors of favorable clinical outcome at 90 days 6
• Time to the start of the procedure is an important predictor of clinical success after thrombectomy in patients with posterior circulation strokes 6
• Favorable clinical outcome at 3 months (modified Rankin Scale score ≤2) was achieved in 35% of patients in one study 6