If you or a loved one are suffering from neurological symptoms or you’ve been told that an MRI scan has revealed abnormalities in your brain tissue, you’re likely to be very concerned about your brain health. But what does it mean if an MRI shows lesions on the brain?

Lesions can appear as areas of damage or abnormal change in the brain's tissues, but they can vary widely in their causes, how severe they are and what they mean for your health. This guide explores what brain lesions are, the potential causes of brain lesions, and what steps you can take if an MRI scan reveals lesions in the brain.

What Are Brain Lesions?

Brain lesions are areas of damaged or abnormal tissue in the brain and can be caused by many different factors, including problems with blood flow, benign or malignant growths, or injuries to the brain.

You might think that brain lesions are the same as brain tumours, but they’re not. A lesion is a broad term that covers any area of damaged or abnormal tissue, and lesions are not always harmful. However, depending on their size, location, and cause, they can sometimes disrupt normal brain function and lead to symptoms like headaches or cognitive difficulties, or neurological problems.

Brain tumours are a specific type of lesion and can be benign (non-cancerous) or malignant (cancerous). So while all tumours are lesions, not all brain lesions are tumours, if that makes sense.

Lesions will appear as white spots on an MRI scan, which uses magnetic resonance imaging to create detailed maps of the brain and spinal cord. They can occur in different parts of the brain, including the white matter, which transmits signals between different areas of the brain and the central nervous system.

What Types of Lesions Are There?

Brain lesions can be categorised into different types depending on how and where they appear and the underlying cause:

Benign and malignant brain tumours.
Demyelination lesions caused by conditions such as multiple sclerosis.
Inflammatory or infectious lesions caused by autoimmune diseases or infections.
Vascular lesions caused by problems with blood flow from strokes or aneurysms.
Traumatic lesions caused by injury to the brain.
Neurodegenerative lesions caused by progressive diseases such as Alzheimer’s disease or Parkinson’s disease.
Congenital lesions, which are present from birth and are caused by abnormal brain development, for example, in cerebral palsy.

What Are the Common Causes of Brain Lesions?

Brain lesions can develop for several reasons, from infections to injuries. Understanding their causes can help your doctors diagnose and treat you more effectively. Here are some of the most common causes:

Infections: Certain infections can lead to brain damage by causing inflammation, swelling or pus-filled areas of the brain called abscesses. Bacterial infections such as Streptococcus and Staphylococcus can create abscesses while viruses, such as those causing encephalitis, can cause swelling and damage to the brain. Fungal or parasitic infections can also form lesions.
Tumours: As well as benign and malignant tumours causing lesions, metastatic tumours (cancer that spreads from other parts of the body) can often cause multiple brain lesions.
Blood flow problems: If blood can’t reach part of the brain it can cause damage.
Head trauma: Head injuries can cause bruises on the brain (contusions), bleeding inside the skull (haematomas), and swelling that can damage the brain tissues.
Autoimmune and inflammatory conditions: MS can damage the brain’s protective coating (myelin), causing multiple lesions, while lupus and sarcoidosis can cause inflammation and strokes in the brain.
Lack of oxygen: Lack of oxygen (hypoxia), such as that experienced after a drowning, heart attack or breathing problems, can lead to brain damage.
Degenerative brain conditions: Alzheimer’s disease causes shrinking (atrophy) of the brain, while rare genetic disorders (leukodystrophies) can damage the brain’s white matter.

Which Medical Conditions Are Associated With Brain Lesions?

Neurological Disorders

Multiple Sclerosis (MS) - MS is a chronic autoimmune disease that affects the central nervous system, including the brain and spinal cord. In MS, the immune sstem attacks the protective coating of the nerve fibres which causes lesions to form in the brain’s white matter. These lesions can disrupt the signals between the brain and the rest of the body, causing symptoms including fatigue, muscle weakness and vision problems.
Epilepsy - Epilepsy is a neurological disorder that causes common seizures. Sometimes brain lesions cause of these seizures, especially if they are located in the areas of the brain that are responsible for electrical activity.
Parkinson’s Disease - Parkinson's is a progressive neurological disorder that causes problems with movement. While it’s usually associated with the loss of dopamine-producing cells in the brain, some people with Parkinson’s may also have brain lesions that contribute to their symptoms.
Alzheimer’s and Other Dementias - Dementias like Alzheimer’s disease can cause damage to the brain tissue, shrinking the brain and causing damage to the blood vessels. Inflammation can also cause damage.

Vascular Conditions

Strokes and Mini-Strokes (TIAs) - Strokes and mini-strokes (transient ischemic attacks or TIAs) can interrupt blood flow to the brain, leading to damage in the affected areas.
Cerebral Small Vessel Disease - This condition affects the brain’s small blood vessels, reducing blood flow and increasing the development of white matter lesions. It’s a common cause of cognitive decline in older people.
Brain Aneurysm - A brain aneurysm is a bulge in a blood vessel that can rupture and cause bleeding in the brain, leading lesions to form with potentially life-threatening complications.

Inflammatory and Autoimmune Diseases

Lupus - Lupus is an autoimmune disease affecting multiple organs, including the brain. In some cases, it can lead to the development of brain lesions.
Vasculitis - Vasculitis is an inflammation of the blood vessels that can disrupt blood flow to the brain and cause lesions.
Sarcoidosis - Sarcoidosis is an inflammatory disease that can affect the brain and spinal cord, causing mini-strokes that can form lesions.

Infections

Encephalitis - Encephalitis is an inflammation of the brain that can be caused by infections. It can lead to the formation of lesions and severe neurological symptoms.
Meningitis - Meningitis is an infection of the membranes surrounding the brain and spinal cord. In severe cases, it can cause brain lesions.
Progressive Multifocal Leukoencephalopathy (PML) - PML is a rare but serious infection of the white matter of the brain, often seen in people with weakened immune systems.

Trauma and Degenerative Conditions

Traumatic Brain Injury (TBI) - TBI can result from a blow to the head or an injury, leading to brain lesions and long-term neurological issues.
Chronic Traumatic Encephalopathy (CTE) - CTE is a degenerative brain condition that can affect people with a history of repeated head trauma, such as footballers. It is associated with the development of brain lesions.
Leukodystrophies - Leukodystrophies are a group of genetic disorders that affect the brain's white matter, leading to the formation of lesions.

Tumours and Growths

Benign Brain Tumours (e.g., Meningiomas) - Benign tumours like meningiomas can grow in the brain and appear as lesions on an MRI scan. While they’re not cancerous, they can still cause symptoms depending on where they are in the brain and their size.
Malignant Brain Tumours (e.g., Glioblastoma) - Malignant tumours like glioblastoma are cancerous and can grow rapidly, causing significant damage to brain tissue.
Metastatic Cancer - Cancer that spreads to the brain from other parts of the body can also appear as lesions on an MRI scan.

Metabolic and Toxic Conditions

Hypoxic-Ischemic Brain Injury - This type of injury occurs when the brain is deprived of oxygen, leading to damage and the formation of lesions.
Wilson’s Disease - Wilson’s disease is a genetic disorder that causes copper to build up in the brain and other organs, leading to brain lesions.
Vitamin B12 Deficiency - A deficiency in vitamin B12 can lead to neurological issues, including the development of brain lesions.

What Are My Next Steps After an MRI Shows Lesions?

Finding out that your MRI scan shows brain lesions can feel overwhelming, but it’s important to remember that not all lesions are serious. They can have many causes, some more serious than others. Your clinician can guide you through the next steps depending on what’s causing the lesions.

Further Testing and Diagnosis

Your doctor will recommend more tests to find out what’s behind the lesions. This could include blood tests to check for autoimmune conditions or infections, a lumbar puncture (spinal tap) to examine the spinal fluid for signs of disease, or more detailed imaging scans to look at the brain from different angles. In some cases, your doctor may recommend a biopsy of the affected tissue for testing. Each test and scan will help to form a bigger picture of what’s happening in your brain.

Treatment Options

What treatment you have next will depend on what’s causing the lesions. However, here are some common treatments based on cause:

Multiple Sclerosis: Medications can help slow the disease’s progression and manage your symptoms.
Infections: If bacteria or viruses are to blame, antibiotics or antiviral treatments may be needed and your doctor may recommend surgery to drain pus-filled abscesses.
Tumours: Your options may include surgery, radiation, or chemotherapy, depending on the type of tumour you have.
Vascular conditions: Treatments may involve medications to improve blood flow or, in some cases, surgery.
Inflammatory conditions: Your doctor may recommend corticosteroids or other immunosuppressive medications to reduce inflammation and prevent more lesions from forming.

What Are the Risk Factors for Developing Brain Lesions?

Certain factors can make brain lesions more likely, including:

Age: Older people have a higher risk, especially for vascular-related brain changes.
Family history: Neurological conditions can sometimes run in families.
Past head injuries: Repeated damage from concussions or trauma can lead to brain changes over time.
Autoimmune conditions or chronic infections: These can contribute to inflammation in the brain.
Lifestyle habits: Smoking, a poor diet and a lack of exercise may increase your risk.

While some risk factors can’t be changed, others - like maintaining a healthy lifestyle and making sure you have regular appointments with your doctor - are within your control.

Don't hesitate to ask your doctor questions if you have any concerns about your MRI results.

In any case, all Scan.com bookings include two clinical consultations. One happens before the scan to ensure your clinician recommends the best scan for you based on your medical history and any symptoms. The second consultation takes place after the scan, where your clinician will clearly explain the results and the next steps.

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Sources:

Brain lesions. (2022). https://my.clevelandclinic.org/health/symptoms/17839-brain-lesions

Brain tumours. (2024). https://www.uhcw.nhs.uk/download/clientfiles/files/Patient%20Information%20Leaflets/Trauma%20and%20Neuro%20services/Neurosurgery/Brain%20Tumours%20-%20a%20guide%20for%20patients%20and%20carers.pdf

Brain Tumors and Brain Cancer. (N.D.) https://www.hopkinsmedicine.org/health/conditions-and-diseases/brain-tumor

Space-occupying lesions of the brain. (2024). https://patient.info/doctor/space-occupying-lesions-of-the-brain

What Do Lesions on a Brain MRI Mean?