Introduction

When COVID-19 first appeared, most people thought of it as a lung disease: you might cough, feel breathless, or need oxygen. However, research over the last few years has shown that the virus that causes COVID-19, SARS-CoV-2, can affect many parts of the body, including the brain and its blood vessels. Problems involving the brain’s blood vessels are known as neurovascular complications. These can include strokes, bleeding in the brain, or blood clots in the veins. Even if someone survives the initial infection, these conditions can cause lasting damage, sometimes affecting movement, speech, vision, or thinking.

Understanding these complications is important for patients, so they can spot warning signs; for healthcare professionals, so they can act early; and for public health planning, because some patients may need long-term care. This article explains how COVID-19 can affect brain vessels, the types of complications it can cause, how doctors detect and treat them, and what patients might expect over time.

How COVID-19 can affect the brain’s blood vessels

COVID-19 can damage the blood vessels in the brain through several mechanisms.

Endothelial dysfunction and vascular injury

The endothelium is the thin lining inside all blood vessels. It helps blood vessels stay flexible, control clotting, and maintain a protective barrier. SARS-CoV-2 can infect endothelial cells through ACE2 receptors, leading to inflammation and damage. This condition, called endotheliopathy, makes vessels leaky and more likely to form clots¹,². When the endothelium is disrupted, blood vessels struggle to regulate dilation, permeability, and clotting.

Hypercoagulability (increased tendency to clot)

COVID-19 often triggers a strong immune response, sometimes called a “cytokine storm.” This causes the blood to become more likely to clot. Doctors can see this in blood tests showing high D-dimer or fibrinogen levels.³^,⁴ Clots can form in large arteries, small vessels, or veins. The combination of clotting and endothelial damage increases the risk of stroke or other brain vessel problems.

Blood-brain barrier disruption

The blood-brain barrier (BBB) protects the brain by keeping harmful substances out. COVID-19-related inflammation and endothelial damage can make the BBB leaky.⁵ Once the barrier is compromised, immune cells, inflammatory molecules, or even blood components can enter the brain, causing further damage.

Other contributing mechanisms

• Autoimmune effects: In some patients, antibodies made in response to the virus may attack the body’s own blood vessels
• Hypoxia: Severe lung infection reduces oxygen in the blood, which can stress brain tissue
• Pre-existing conditions: Diabetes, high blood pressure, and other chronic illnesses make vessels more vulnerable³

Types of neurovascular complications

COVID-19 can lead to several kinds of neurovascular problems.

Ischaemic stroke

An ischaemic stroke occurs when a blood vessel supplying the brain becomes blocked, depriving that area of oxygen. This is one of the most common brain-vessel complications of COVID-19. Patients with COVID-19 who undergo mechanical thrombectomy (removal of clots from brain arteries) often have worse outcomes than non-COVID stroke patients, including lower success in reopening vessels and higher complication rates⁶. Risk is especially high in those with other conditions like hypertension or obesity.⁷

Haemorrhagic stroke and spontaneous bleeding

A haemorrhagic stroke involves bleeding in or around the brain. It is less common than ischaemic stroke in COVID-19, but it can occur due to damaged vessel walls, use of blood thinners, or clotting problems. Cases of spontaneous brain bleeding in post-COVID patients without trauma or blood-thinning medication suggest inflammation and endothelial damage can weaken vessels.⁷^,⁸

Cerebral venous sinus thrombosis (CVST)

CVST occurs when clots form in the veins that drain blood from the brain. This can lead to increased pressure in the brain, swelling, and sometimes haemorrhage. COVID-19 has been linked to venous clots, even in younger patients with severe illness.⁷

Microvascular injury and long-term changes

Even without a major stroke or bleeding, small blood vessels in the brain may be damaged. This can show up on MRI as tiny infarcts or microbleeds. Chronic endothelial dysfunction and inflammation can contribute to cognitive problems, “brain fog,” and other neurological symptoms seen in long COVID.⁶^,⁹

Clinical manifestations and diagnosis

Signs and symptoms

Patients may notice:

• Sudden weakness or numbness in one side of the body
• Difficulty speaking or understanding speech
• Sudden vision changes
• Dizziness, loss of balance, or coordination problems
• Severe headache, especially with haemorrhagic events
• Confusion, altered consciousness, or seizures

Because COVID-19 can already cause fatigue and general illness, these warning signs may be overlooked. Prompt recognition is crucial.

How it is diagnosed

• Neuroimaging: CT scans (quick, detect bleeding), MRI (detect smaller lesions), angiography (view arteries), venography (view veins)
• Laboratory tests: D-dimer, fibrinogen, platelet counts, coagulation profile, inflammatory markers
• Clinical assessment: Neurological exams, assessing symptom onset, severity, and risk factors

Management and treatment

Treatment follows standard care for strokes and bleeding but must be adapted due to COVID-19 risks.

Ischaemic stroke: Clot-busting drugs (thrombolysis) and thrombectomy are used when appropriate, balancing bleeding risk.

Haemorrhagic stroke/bleeding: Supportive care includes controlling blood pressure, reducing intracranial pressure, and sometimes surgery. Anticoagulants must be managed carefully.

CVST: Blood thinners are used even if some bleeding risk exists, as preventing clot spread is critical.

Supportive and multidisciplinary care: Recovery often requires rehabilitation for movement, speech, and cognitive skills. Specialists include neurologists, physiotherapists, occupational therapists, and speech-language therapists.

Management of risk factors: Blood pressure, diabetes, inflammation, and clotting tendencies should be optimised.

Long-term implications

Many COVID-19 survivors with neurovascular complications experience persistent deficits, including weakness, speech difficulties, or vision problems. Cognitive problems such as memory and attention deficits are common in long COVID, likely due to microvascular injury, inflammation, and BBB disruption.⁹ Those who had neurovascular events may also have a higher risk of future strokes or vessel problems. Healthcare systems must plan for rehabilitation and long-term follow-up, including vascular monitoring months after infection.

FAQs

Can COVID-19 cause a stroke in young, healthy people?

Even younger individuals without traditional risk factors may have ischaemic strokes due to virus-induced clotting and endothelial damage.

How soon after infection can neurovascular complications appear?

They can occur during the acute illness (days to weeks) or after recovery. Some clotting or vessel damage may persist, so risk may continue beyond initial recovery.

Are vaccinated people at lower risk?

Vaccination reduces severity of illness and inflammation, which lowers the risk of serious neurovascular complications. Severe breakthrough infections may still pose risks.

What are the warning signs to seek urgent care?

Use “FAST” – Face drooping, Arm weakness, Speech difficulty, Time to call. Also seek help for sudden severe headache, confusion, vision changes, or loss of coordination, especially if there is a recent COVID-19 infection.

How do treatments differ from non-COVID strokes?

Primary treatments are similar (thrombolysis, thrombectomy, anticoagulation), but COVID-19 may increase bleeding risk or affect other organs, requiring careful monitoring and adjustments.

Do these complications contribute to “long COVID”?

Yes. Cognitive deficits, fatigue, and memory problems in long COVID may result from microvascular injury and ongoing inflammation, even in patients without overt strokes.

Summary

COVID-19 is more than a respiratory illness. Its effects on the brain’s blood vessels can lead to serious neurovascular complications, including strokes, venous thrombosis, and microvascular damage. Early recognition of warning signs, timely imaging and laboratory tests, and multidisciplinary treatment are essential. Long-term monitoring and rehabilitation are vital to improving outcomes for survivors.