What Diseases Can Cause Lesions On The Brain? What Is The Most Common Cause Of Lesions In The Brain?

A brain lesion has a characteristic appearance that will help your doctor determine its cause. Sometimes the cause of the abnormal-appearing area cannot be diagnosed by the image alone, and additional or follow-up tests may be necessary. Follow this article to learn about what diseases can cause lesions on the brain?

Brain lesions are areas of brain tissue that show damage from injury or disease. The most common way to detect brain lesions is with diagnostic imaging scans. Depending on the cause, some types of brain lesions will heal on their own or are treatable. However, some brain lesions are permanent or happen for reasons that can’t be treated or cured.

Brain lesions are areas of damaged brain tissue. This kind of damage happens because of brain injuries or medical conditions. A stroke, for example, is a type of brain lesion. Lesions can disrupt the way your brain works, causing a wide range of symptoms, such as weakness, disruption of one or more senses and confusion.

When it comes to your brain, communication is everything. Your brain uses electrical and chemical signals to communicate inside your brain itself and with areas throughout your body. When you have a brain lesion, the damage can disrupt communication in the affected brain area(s). The more severe the damage, the greater the disruption. Follow this article to learn more about what diseases can cause lesions on the brain.

What is a brain lesion?

A brain lesion is an abnormality seen on a brain-imaging test, such as magnetic resonance imaging (MRI) or computerized tomography (CT). On CT or MRI scans, brain lesions appear as dark or light spots that don’t look like normal brain tissue. Usually, a brain lesion is an incidental finding unrelated to the condition or symptom that led to the imaging test in the first place. A brain lesion may involve small to large areas of your brain, and the severity of the underlying condition may range from relatively minor to life-threatening.

An intracranial lesion or brain lesion is damage to the brain tissue because of illness, injury, disease or infection, or some other cause. The cause of a brain lesion is sometimes unknown. The lesions are often found during an MRI or CT scan being performed to test for or diagnose some other condition. The lesion shows up as a light or dark area on the brain.

A lesion is an area of tissue that has been damaged through injury or disease. So a brain lesion is an area of injury or disease within the brain. While the definition sounds simple, understanding brain lesions can be complicated. That’s because there are many types of brain lesions. They can range from small to large, from few to many, from relatively harmless to life threatening.

When you scrape your elbow, it leaves an area of inflamed skin, or a lesion. But what are lesions in the brain? And what causes them? How serious are brain lesions and how are they treated? Here is information about this confusing and unsettling health concern.

What are the types of brain lesions?

Although they share a common definition – injury or damage to tissue within the brain, brain lesions vary greatly. Here are some common brain lesions:

  • Abscesses
  • Arteriovenous malformations (AVMs)
  • Cerebral infarction
    • Cerebral palsy
    • Multiple sclerosis
  • Tumors


Brain abscesses are areas of infection, including pus and inflamed tissue. They are not common, but they are life threatening. Brain abscesses often occur after an infection, usually in a nearby area, such as an ear, sinus, or dental infection. They can also appear after injury or surgery to the skull. Read more about the causes of abscesses.

Arteriovenous malformations (AVMs):

An AVM is a type of brain lesion that occurs during early development. Arteries and veins in the brain grow in a tangle and become connected by tube-like structures called fistulae. The arteries are not as strong as normal arteries. The veins are often enlarged because of the constant flow of blood directly from the arteries through the fistulae to the veins. These fragile vessels may rupture, leaking blood into the brain. In addition, the brain tissue may not receive enough blood to function properly. Damage to the brain may cause seizures as the first symptoms of an AVM.

Cerebral infarction:

Infarction refers to death of tissue. A cerebral infarction, or stroke, is a brain lesion in which a cluster of brain cells die when they don’t get enough blood. Recognize the signs and symptoms of a stroke.

Cerebral palsy:

This type of brain lesion occurs when a baby is still in the mother’s womb, or during delivery. Cerebral palsy does not progress over time. The brain lesions affect the child’s ability to move, which can also make communication and related skills difficult. However, many children with cerebral palsy have normal intellectual functioning.

Multiple sclerosis:

With this condition, the immune system attacks and damages the nerve linings (myelin) in the brain and spinal cord. These lesions make it difficult for messages to be sent and received properly between the brain and the rest of the body.


Tumors are clumps of cells that grow abnormally from normal tissue. Some tumors in the brain are noncancerous, or benign. Others are cancerous. They may start in the brain, or they may spread from elsewhere in the body (metastatic). They may grow quickly or they may remain stable.

What are the causes of brain lesions?

Brain lesions can be caused by injury, infection, exposure to certain chemicals, problems with the immune system, and more. Following are some of the main causes of brain lesion:

  • Trauma
  • Inflammation with brain tissue
  • Autoimmune diseases
  • Certain diseases
  • Cerebral infarction
  • Bleeding
  • Tumors
  • Pituitary adenomas


Trauma is the most widely recognized cause of acute brain injury. Bleeding or swelling within the skull can directly damage brain cells or the pressure that can build within the skull can compress the brain and compromise its ability to function. Trauma can also damage the brain on a microscopic level. Shear injuries describe damage to the synapse connections between brain cells decreasing their ability to communicate with each other.

Inflammation with brain tissues:

Inflammation within brain tissue can affect function. This inflammation may be due to infections that cause meningitis and encephalitis. Other infections may cause discrete changes within the brain tissue. Neurocysticercosis, for example, is the most common cause of epilepsy in the developing world; the parasite causes small calcifications that are scattered throughout the brain. Infections may also form abscesses within the brain that can lead to symptoms.

Autoimmune diseases:

Inflammatory and autoimmune diseases that may affect brain function include sarcoidosis, amyloidosis, inflammatory bowel disease, and rheumatoid arthritis. Some of the brain damage may be caused by inflammation of the blood vessels in the brain, which causes strokes.

Certain diseases:

Certain diseases affect only specific cells within the brain. For example, the symptoms of multiple sclerosis are caused by damage to the glial cells that manufacture and maintain the myelin sheath that insulates axons. Without this normal nerve covering, electrical transmission is compromised and symptoms may occur. Alzheimer’s disease and other dementias occur when neuron cells are affected and die prematurely.

Cerebral infarction:

Stroke or cerebral infarction (cerebral=brain + infarction=loss of blood supply) describes the condition where the blood supply to part of the brain is lost and the brain stops functioning. There are numerous reasons for blood supply to decrease. There may be a gradual narrowing of an artery to part of the brain, a blockage may occur should debris from a diseased carotid artery break loose, or a clot may travel or embolize from the heart.


Bleeding may occur from a cerebral aneurysm or arteriovenous malformation or because of uncontrolled hypertension (high blood pressure).


Tumors that originate from brain cells or those that metastasize from other organs can affect brain function in two ways. The tumor can destroy brain cells so that their function is lost, or the tumor can take up space and cause pressure and swelling that affects brain cell function. This may occur with benign or cancerous tumors. Common tumors that arise from the brain include meningiomas, adenomas, and gliomas.

Pituitary adenomas:

Pituitary adenomas are common benign tumors that grow in the sella turcica, where the pituitary gland sits and near where the optic nerves travel from the eyes to the occiput in the back of the brain. As the tumor grows it can push on the optic nerve and cause visual changes and blindness.

What are the symptoms of brain lesions?

Symptoms of a brain lesion depend upon what part of the brain is affected. Large parts of the brain can be involved in some diseases and there may be relatively few symptoms. Alternatively, very tiny lesions may be catastrophic if they occur in a critical part of the brain. For example, the reticular activating system (RAS) is a tiny area located within the brainstem that is effectively the master on/off switch of the brain.

If a midbrain stroke affects this area, the result is a permanent coma. A patient needs the RAS and one functioning hemisphere of the cortex to be awake. If the patient is unconscious, then the RAS isn’t working or there is significant damage to both sides of the brain. Initial signs and symptoms of a brain lesion are often non-specific and may include:

  • Headache
  • Nausea
  • Neck pain
  • Affected vision
  • Affected speech
  • Paralysis
  • Seizures
  • Memory loss
  • Personality changes


Individuals should seek medical care for new-onset headaches or if headaches are associated with brain lesions, stiff neck, weakness, change in sensation on one side of the body, change in vision, vomiting, or change in behavior that may be caused by the development of serious infections.


Positional vomiting is an important alerting sign for the presence of a brainstem central nervous system (CNS) lesion. Failure to identify another cause of protracted vomiting should prompt consideration of a CNS cause.

Neck pain:

Neck pain can come from common infections, such as virus infection of the throat, leading to lymph node (gland) swelling and neck pain. Neck pain can also come from rare infections, such as tuberculosis of the neck, infection of the spine bones in the neck (osteomyelitis and septic discitis), and meningitis (often accompanied by neck stiffness).

Affected vision:

Although eye problems typically stem from conditions unrelated to brain tumors—such as astigmatism, cataracts, detached retina and age-related degeneration—they can sometimes be caused by tumors within the brain.

Affected speech:

Aphasia is a language disorder caused by damage to parts of the brain that control speech and understanding of language. Depending on which areas of the brain are affected, a person might have different levels of ability to speak and understand others.


Certain areas of the brain send signals to the muscles, making movement possible. When these areas are damaged with traumatic brain injury, the signals are interrupted, the muscles are unable to respond, and a portion of the body becomes paralyzed.


Some types of lesions — such as cavernous malformations (blood vessel abnormality) and tumors — are prone to cause seizures. When the pre-operative testing indicates that these lesions are the cause of the epilepsy, they can be removed surgically.

Memory loss:

If lesions develop on parts of the brain that process memories, it can lead to memory loss. Memory loss is one of the most common cognitive changes in people with MS. Brain lesions can also affect other cognitive functions, such as attention, concentration, and ability to process information.

Personality changes:

Brain lesions often cause personality changes and sudden mood swings. Although these mood changes and their severity will vary from one person to another, it’s relatively common for someone with a brain tumor to experience increased: Aggression.

What diseases can cause lesions on the brain?

The different types of diseases are each associated with brain lesions with certain causes and risk factors. Following are some of the main diseases that can cause brain lesions:

  • Stroke
  • Demyelination
  • Infection
  • Inflammation
  • Cancer
  • Vascular malformations
  • Contusion
  • Hemorrhage
  • Ventricular dilatation
  • Congenital malformation


An interruption in blood flow within the brain can cause a stroke, which is a small or large area of brain damage. Risk factors include heart disease, high blood pressure, uncontrolled diabetes, and high cholesterol. This lesion usually consists of a central area of ischemia (death of cells due to deficient blood supply).

Right after a stroke occurs, the lesion may be surrounded by swelling and inflammation, which subside within a few weeks. The ischemic part of the lesion remains, with permanent damage to the affected area of the brain.


Some conditions, such as multiple sclerosis (MS), are caused by temporary or lasting demyelination—loss of the protective myelin coating that surrounds nerves in the brain. This causes one or more demyelinating brain lesions. The condition is usually idiopathic (without a known cause).

A more serious condition, progressive multifocal leukoencephalopathy (PML), is considered a demyelinating inflammatory response to a virus that is usually harmless. PML generally affects people who are severely immunocompromised, and it has a high mortality rate.


Bacterial, fungal, viral, or parasitic brain infections can cause one or more areas of damage and inflammation. Many types of brain infections can resolve with appropriate treatment.


Inflammatory lesions in the brain can develop due to conditions like lupus, sarcoidosis, therapeutic brain radiation, and more.


Brain tumors and metastatic tumors from elsewhere in the body can cause one or more lesions throughout the brain. The cause of brain tumors is usually unknown. Tumors that metastasize and cause lesions in the brain may have known risk factors. For example, smoking increases the risk of lung cancer, which can spread to the brain.

Vascular malformations:

Vascular malformations such as brain aneurysms and arteriovenous malformations (AVMs) are usually idiopathic. They can be congenital (present from birth) or develop later in life. These lesions can cause focal neurological deficits when they are small, but they may cause rapid bleeding and severe swelling in the brain if the malformed blood vessels bleed—and could lead to death.


Head trauma can lead to a bruise in the brain, which may cause a combination of generalized and focal effects. Contusions in the brain usually partially or fully heal over time. However, repeated blows to the head with multiple lesions can cause chronic traumatic encephalopathy (CTE), with persistent changes.


Bleeding in the brain can cause a hemorrhagic lesion. These lesions are more life-threatening than non-hemorrhagic lesions. A number of problems can lead to hemorrhagic lesions, including a bleeding vascular malformation, hemorrhagic conversion of an ischemic stroke, brain tumors that bleed, and head trauma.

Ventricular dilatation:

Sometimes the brain can shrink in size due to damage or dying of the brain cells. This is usually a result of dementia or extensive strokes.1 This can lead to enlarged spaces within the skull, often noted as atrophic lesions.

Congenital malformation:

Developmental compromise during fetal development can lead to lesions in which areas of the brain are shaped differently than they would be in a healthy brain. Sometimes these malformations lead to impaired physical and cognitive deficits and seizures. Congenital malformation of the brain can result from genetics or issues such as toxins or insufficient oxygen supply during fetal growth.

What is the most common cause of lesions in the brain?

Strokes are one of the most common causes of brain lesions, and you can often prevent a stroke, or at least delay when you have one or limit how severe it is. A stroke, sometimes called a brain attack, occurs when something blocks blood supply to part of the brain or when a blood vessel in the brain bursts. In either case, parts of the brain become damaged or die. A stroke can cause lasting brain damage, long-term disability, or even death.

If you or someone you’re with may be having a stroke, pay particular attention to the time the symptoms began. Some treatment options are most effective when given soon after a stroke begins.

Signs and symptoms of stroke include:

  • Trouble speaking and understanding what others are saying. You may experience confusion, slur words or have difficulty understanding speech.
  • Paralysis of face, arm, or leg. You may develop sudden numbness, weakness or paralysis in the face, arm or leg. This often affects just one side of the body. Try to raise both your arms over your head at the same time. If one arm begins to fall, you may be having a stroke. Also, one side of your mouth may droop when you try to smile.
  • Problem seeing from one or both eyes. You may suddenly have blurred or blackened vision in one or both eyes, or you may see double.
  • A sudden, severe headache, which may be accompanied by vomiting, dizziness or altered consciousness, may indicate that you’re having a stroke.
  • Trouble walking. You may stumble or lose your balance. You may also have sudden dizziness or a loss of coordination.

Seek immediate medical attention if you notice any signs or symptoms of a stroke, even if they seem to come and go or they disappear completely. Think fast and do the following:

  • Ask the person to smile, see if one side of the face drops.
  • Ask the person to raise both arms, look if one arm drifts downward or is one arm unable to rise.
  • Ask the person to repeat a phrase and see if their speech is slurred or strange.

How are brain lesions treated?

Treatment depends on the type of brain lesion. The goals of treatment may be to provide a cure, relieve symptoms, or improve the quality or length of life. Common approaches for treating brain lesions include the following:

  • Wait and see if the lesion is not causing problems and is not growing, you may only need periodic checkups.
  • Surgical removal of the lesion, if possible; new surgical techniques may make it possible to remove even hard-to-reach lesions.
  • Chemotherapy and radiation therapy for lesions that are cancerous.
  • Medication to fight infections, such as antibiotics or other antimicrobial drugs.
  • Medication to calm the immune system or otherwise change the immune system’s response.
  • Medication or other therapies to relieve symptoms associated with the brain lesion.

Brain lesions can happen for many reasons, which means there are many ways to treat them. Your provider will base their treatment recommendations on the underlying cause of your brain lesion. Some conditions that cause brain lesions, like a mild concussion, go away on their own. If the lesion isn’t severe, treatments are unnecessary. Rest and reduced activity are often all that you’ll need.

Other conditions that cause brain lesions are treatable in different ways. Infections are often treatable with antibiotics or supportive care. Growths or tumors — especially easy-to-reach ones — may be removable with surgery. Some lesions are very small and don’t cause symptoms or harm.

Unfortunately, there are also times when brain lesions aren’t treatable. This is most likely with lesions that cause severe damage. The same is true for incurable conditions like Alzheimer’s disease. Because the treatment options can vary, your healthcare provider is the best person to tell you which one(s) they recommend and why.

How can brain lesions be prevented?

Brain lesions are sometimes preventable, depending on the cause. The types of lesions that are most preventable are those that happen because of concussions and traumatic brain injuries. Treating infections in your body promptly can also prevent an infection from spreading to your brain and causing damage.

Some of the most helpful things you can do to prevent brain lesions, or at least reduce your risk of developing them, include:

  • Eat a balanced diet. Your diet plays a key role in your circulatory health. Strokes are one of the most common causes of brain lesions, and you can often prevent a stroke, or at least delay when you have one or limit how severe it is.
  • Stay physically active and maintain a weight that’s healthy for you. Your weight and activity level can prevent or delay conditions that affect your brain, especially circulatory problems like high blood pressure. Your healthcare provider can tell you the ideal weight range for you and help you plan out how to reach and maintain it.
  • Wear safety equipment as needed. Head injuries, especially concussions and traumatic brain injuries, are very common causes of brain lesions. Wearing safety equipment especially helmets or head-protecting gear is vital. Seat belts (or similar safety restraints) are also crucial to preventing head injuries. Use these whenever recommended, regardless of whether you’re at work or on your own time.
  • Manage your chronic conditions. Many conditions that cause brain lesions are often manageable. An example of this is epilepsy, which you can often manage with medication. Preventing seizures or reducing their severity can help avoid damage to your brain tissue.


Brain lesions can happen for many reasons, making them a very common sign of a brain-related condition. Some lesions are minor and need little or no treatment to heal. Others are more severe and may need medical care, such as surgery. Unfortunately, some lesions are severe, permanent or happen for reasons that aren’t treatable.

Advances in medical imaging mean healthcare providers are better able to detect and analyze brain lesions. These imaging technologies are also key in planning out possible treatments and predicting your case’s possible or likely outcomes. Advances in medicine’s understanding of the brain also offer new possibilities for treatment or recovery from brain lesions and the conditions that cause them.