How do the localization of lesions in the brain and blood circulation, specifically the carotid and vertebrobasilar systems, affect stroke symptoms and outcomes?

From the Guidelines

The localization of lesions in the brain and the affected blood circulation, specifically the carotid and vertebrobasilar systems, significantly determine stroke symptoms and outcomes, with carotid-related strokes often being disabling or fatal due to a larger clot burden and poor response to thrombolytic therapy 1.

Blood Circulation and Stroke Symptoms

The carotid system, which supplies the anterior brain including frontal and parietal lobes, typically causes contralateral weakness or numbness, language deficits (if in the dominant hemisphere), visual field cuts, and cognitive changes when affected by a stroke.

• The vertebrobasilar system, affecting the posterior circulation that supplies the brainstem, cerebellum, and occipital lobes, often presents with dizziness, ataxia, diplopia, bilateral weakness, visual field defects, and sometimes altered consciousness.
• Brainstem lesions can be particularly dangerous as they may affect vital functions like breathing and heart rate regulation.

Lesion Location and Outcome

The size and precise location of the lesion determine symptom severity and recovery potential.

• Small, localized lesions may cause specific deficits with better recovery prospects,
• while large vessel occlusions affecting major territories typically result in more severe symptoms and poorer outcomes.

Importance of Collateral Circulation

Collateral circulation plays a crucial role in outcome determination; patients with good collateral networks often experience less severe damage even with major vessel occlusions.

Time-Sensitive Treatment

Time is critical in stroke management, as brain tissue dies rapidly without blood flow, making prompt treatment with thrombolytics (like IV alteplase within 4.5 hours) or mechanical thrombectomy (within 24 hours for selected patients) essential for preserving brain function and improving outcomes, with recent evidence suggesting that emergency carotid lesion treatment should be performed both in ‘isolated’ carotid (sub)occlusions and in tandem lesions 1.

Recent Evidence on Carotid-Related Strokes

Recent evidence shows that tandem strokes, defined as acute ischaemic events in a carotid territory presenting with an extra-cranial ICA stenosis or occlusion and a co-incident ipsilateral large vessel occlusion, account for 20–30% of all ischaemic stroke cases, and carotid-related strokes are often disabling or fatal due to a larger clot burden and poor response to thrombolytic therapy 1.

Mechanical Reperfusion Therapies

Mechanical reperfusion therapies are a powerful therapeutic option for carotid-related strokes, with endovascular extracranial carotid revascularization (with intra-cranial MT, in case of co-existing intra-cranial large vessel occlusion) associated with higher recanalization rates and markedly improved functional outcomes compared with thrombolysis 1.

From the Research

Strokes Based on Localization of Lesion in the Brain

The localization of lesions in the brain plays a crucial role in determining stroke symptoms and outcomes. Strokes can occur in various parts of the brain, including:

• The internal carotid artery, which supplies blood to the anterior circulation of the brain 2, 3, 4
• The middle cerebral artery, which supplies blood to the lateral surface of the brain 2, 4
• The basilar artery, which supplies blood to the posterior circulation of the brain 2, 4
• The vertebrobasilar system, which supplies blood to the brainstem and cerebellum 2

Blood Circulation of the Area

The blood circulation of the brain is complex and involves two main systems:

• The carotid system, which includes the internal carotid artery and its branches 2, 3, 4
• The vertebrobasilar system, which includes the vertebral arteries and the basilar artery 2, 4 The carotid system supplies blood to the anterior two-thirds of the brain, while the vertebrobasilar system supplies blood to the posterior one-third of the brain.

Effect of Localization on Stroke Symptoms and Outcomes

The localization of lesions in the brain can affect stroke symptoms and outcomes in several ways:

• Lesions in the internal carotid artery can cause symptoms such as weakness, numbness, and vision changes in the face and arm 3
• Lesions in the middle cerebral artery can cause symptoms such as weakness, numbness, and vision changes in the face and arm, as well as language and cognitive deficits 2, 4
• Lesions in the basilar artery can cause symptoms such as weakness, numbness, and vision changes in the face and arm, as well as balance and coordination problems 2, 4
• Lesions in the vertebrobasilar system can cause symptoms such as weakness, numbness, and vision changes in the face and arm, as well as balance and coordination problems, and can also affect the brainstem and cerebellum 2

Treatment Options

Treatment options for strokes depend on the localization of the lesion and the severity of the symptoms. Some common treatment options include:

• Intravenous thrombolysis with alteplase or tenecteplase 2, 5, 4
• Mechanical thrombectomy 2, 3, 4, 6
• Dual antiplatelet therapy 5
• Carotid angioplasty and stenting 3
• Middle cerebral artery angioplasty 3

Key Findings

Some key findings from the studies include:

• Tenecteplase may be more effective than alteplase in achieving reperfusion and improving functional outcomes in patients with acute ischemic stroke 2, 4
• Dual antiplatelet therapy may be noninferior to intravenous thrombolysis in patients with minor nondisabling acute ischemic stroke 5
• Mechanical thrombectomy can be effective in achieving reperfusion and improving functional outcomes in patients with acute ischemic stroke, especially when used in combination with advanced neuroimaging 3, 6
• Advanced neuroimaging can help select patients who are most likely to benefit from mechanical thrombectomy and improve clinical outcomes 6