Encephalitis MRI: Info and Get a Scan

Encephalitis is a rare but serious condition that causes inflammation in the brain. It often starts with a virus or an overactive immune response, but with the right treatment, many people go on to make a full recovery.

If you’ve been feeling confused, unwell, or not quite yourself, an MRI scan can help uncover what’s going on. It’s one of the best tools we have to detect encephalitis and guide treatment decisions quickly and safely.

Key Takeaways:

• Encephalitis is a rare but serious condition that causes inflammation in the brain.

• It’s often triggered by viruses or autoimmune reactions, but many people make a full recovery with treatment.

• An MRI scan is one of the best ways to confirm encephalitis and guide your treatment.

• Symptoms can range from mild confusion to seizures or changes in personality.

• If you’re worried about your symptoms, an MRI scan can offer peace of mind and help you take the next step.

What is encephalitis?

Encephalitis is the medical term for inflammation in the brain. It’s an uncommon but serious medical condition, often triggered by an infection or an abnormal immune response. Around 6,000 people in the UK develop encephalitis every year. 

It can be frightening and overwhelming to hear the phrase “inflammation of the brain,” especially if you or a loved one has just been diagnosed or referred for further tests. Unfortunately, the condition can be life-threatening, and often needs urgent treatment, but it’s important to remember that many people with encephalitis recover completely, especially when it’s diagnosed early and treated quickly. 

An early MRI (magnetic resonance imaging) scan and the right diagnosis can make all the difference to your treatment and outlook.

While people of all ages can develop encephalitis, it’s more common in children, older adults, and people with weakened immune systems.

What causes encephalitis and what types of encephalitis are there?

Encephalitis isn’t just one condition. It’s a reaction that can be triggered in several different ways. The causes of encephalitis usually fall into three main categories:

1. Infections, especially viral infections.

2. Autoimmune responses, where your immune system mistakenly attacks your brain tissue.

3. Unknown causes, which are sometimes called idiopathic encephalitis.

Viral encephalitis

This is the most common type. It happens when a virus directly infects the brain and causes swelling and damage. Common viruses that cause encephalitis include:

• Herpes simplex virus (HSV): A common virus that causes severe encephalitis without treatment, but responds well to antiviral treatment if it’s caught early.

• Varicella-zoster virus: The virus that causes chickenpox and shingles.

• Enteroviruses: More common in children, enteroviruses can spread easily in groups. Encephalitis itself cannot be spread by human contact though.

• Mosquito and tick-borne viruses: Tick-borne encephalitis (TBE) virus is spread through the bites of infected ticks. West Nile virus and St. Louis encephalitis virus can be transmitted via mosquito bites and can also cause encephalitis.

• Measles, mumps, rubella: Now rare due to vaccinations, but still possible if unvaccinated, and on the rise in the UK.

While bacterial or fungal infections can also cause encephalitis, this is much rarer than viral infections.

Autoimmune encephalitis

Autoimmune encephalitis happens when your immune system goes into overdrive and starts attacking healthy brain tissue by mistake. It can be triggered by an infection, or a tumour, or sometimes it just happens without a clear reason.

In many cases, this type of encephalitis is linked to specific antibodies, which are proteins your immune system makes when it’s trying to fight something off. One of the most well-known is called the NMDA (N-methyl-D-aspartate) receptor antibody. These antibodies target NMDA receptors, which are found on brain cells and play a big role in memory, behaviour, and how your brain communicates.

Finding these antibodies in your blood or spinal fluid helps confirm the diagnosis. It also guides treatment. For example:

• You may be given steroids or immunotherapy to calm down the immune response.

• You might need plasma exchange or IV immunoglobulin (IVIG) to help remove or block the harmful antibodies.

• If a tumour is causing the immune reaction, it may need to be surgically removed.

Getting the right diagnosis quickly, especially if specific antibodies are involved, can dramatically improve your chances of recovery.

Acute disseminated encephalomyelitis (ADEM)

This type is more common in children and often appears after a viral illness. It causes a short burst of inflammation in the brain and spinal cord. It usually responds well to steroids.

Limbic encephalitis

This type affects the limbic system - the part of your brain responsible for emotions, behaviour, and memory. It may be linked to certain types of cancer or autoimmune responses, and can cause symptoms such as confusion, memory problems, or changes in personality.

What symptoms of encephalitis should I look out for?

Symptoms can vary widely and change from person to person. Encephalitis affects the central nervous system, which includes the brain and spinal cord. Because these areas control so many important functions like movement, memory, and feeling, inflammation here can affect each individual very differently.

Some people experience mild flu-like symptoms at first, while others may suddenly become confused, disoriented, or unconscious, with no warning at all.

Common symptoms of encephalitis include:

• Fever and headache

• Confusion or difficulty speaking

• Seizures or fits

• Sensitivity to light

• Drowsiness or loss of consciousness

• Personality or behavioural changes

• Weakness or lack of coordination

• Nausea and vomiting

Symptoms can appear over a few days or come on suddenly. In some cases, people may seem fine one day and confused or drowsy the next. That’s why it’s so important to trust your instincts. If something feels wrong, don’t wait. Get advice as soon as possible and dial 999.

The clinical presentation of encephalitis can also vary depending on which parts of your brain are affected. For example, if you have inflammation in the frontal lobes of the brain, you may experience changes in personality or behaviour. If a group of structures inside the brain, called the basal ganglia, are affected, you may experience difficulties with movement and coordination.

In babies and toddlers, signs may include a bulging soft spot on the skull (fontanelle), poor feeding, irritability, or stiffness. In children, it may even look like a viral illness at first. If your child has a high fever and becomes unusually sleepy, floppy, or difficult to wake, get urgent medical help. It’s always better to get checked than to wait and see.

How will my doctor diagnose encephalitis?

Diagnosing encephalitis can be tricky for doctors, especially in the early stages. That’s why they’ll use a combination of tests to build a full picture and rule out any other possible causes.

1. Clinical history and physical exam - Your doctor will ask about recent illnesses, your travel history, any vaccinations you’ve had, and what symptoms you’re experiencing. They’ll also give you a neurological examination to check how well your memory, reflexes, coordination, and speech are working.

2. Lumbar puncture (spinal tap) - A spinal tap involves taking a sample of cerebrospinal fluid (CSF) from your spine. This is the clear liquid that surrounds your brain and spinal cord. Your doctor tests this for signs of infection or inflammation.

3. MRI scan of the brain - MRI is one of the most useful imaging tools for detecting encephalitis. MRI images can show areas of swelling and inflammation in the brain that could be caused by encephalitis. It can also show other  abnormalities that aren’t visible with other scans, such as brain aneurysms or subtle injuries to the brain.

4. EEG (electroencephalogram) - An EEG records the electrical activity in your brain and can show abnormal patterns that may be linked to encephalitis or seizures.

5. Blood and antibody tests - These can help identify viruses, bacteria, or autoimmune antibodies that may be responsible for encephalitis, or explain your symptoms better.

6. Additional scans - In some cases, your doctor might request extra tests and scans, such as a chest X-ray, CT scan, or even an ultrasound to look for underlying causes or differential diagnoses, including cancer or hidden infections.

How can an MRI scan help with diagnosing encephalitis?

MRI scans are one of the best tools for spotting encephalitis. Unlike X-rays or CT scans, MRI provides detailed images of your brain’s soft tissues, allowing doctors to spot even subtle changes. They don’t involve any radiation and are completely non-invasive. This makes them safe for pregnant women, children and babies. 

The scan uses a strong magnetic field and radio waves to create detailed images of your brain. You may be given a contrast dye (called gadolinium) through a small injection in your arm to help highlight inflammation more clearly.

An MRI can show:

• Areas of the brain which are inflamed.

• Abnormal signals in specific parts of the brain (such as the temporal lobes, which are often affected in herpes encephalitis).

• Lesions or signs of damage from autoimmune conditions.

• Whether the inflammation is widespread or just in one part of your brain.

This helps your doctor confirm which type of encephalitis you have, identify the likely cause, and tailor your treatment much more effectively.

For example, if an MRI shows inflammation in the medial temporal lobes, your doctor might suspect herpes simplex virus. If it shows widespread changes across the brain, they may think that ADEM is more likely to be the cause.

Neuroimaging methods like magnetic resonance imaging (MRI), especially T2-weighted scans, play an important role in spotting any swelling or damage in the soft tissues of the brain. These scans help doctors tell encephalitis apart from other similar conditions when making a differential diagnosis.

What does treatment for encephalitis involve?

Treatment can depend on what’s causing the encephalitis, but the goal is always the same: to reduce inflammation and pain, fight the underlying cause, and support the brain as it heals.

If the cause is a virus:

• You’ll likely receive antiviral medication, such as aciclovir, as well as painkillers.

• You’ll have care in hospital, including fluids, oxygen or medication to reduce symptoms such as a raised temperature, swelling and seizures. 

If the cause is autoimmune:

• You may be given steroids, plasma exchange, or immunosuppressants to calm your immune system sometimes. 
• Your medical team may need to give you IV immunoglobulin (IVIG) to help neutralise harmful antibodies.

Recovery in hospital can take several weeks or even months. You may need rehabilitation or speech therapy to rebuild any skills affected by the inflammation. It’s completely normal to feel tired, foggy or low during this time. It’s important to share any changes with your healthcare provider and keep in touch with friends and family for moral support.

What’s the outlook for people with encephalitis?

Some people recover fully within weeks or months. Others may have long-term complications. The overall outlook depends on several factors, including:

• The cause of encephalitis

• How quickly treatment started

• Your age and overall health

• Which parts of your brain were affected

This sounds scary, but early treatment often leads to better outcomes. So getting an MRI scan early is the right thing to do if you’re worried.

Unfortunately, many people with encephalitis do experience long-lasting or permanent complications that may include: 

• Problems with memory, concentration and problem-solving

• Seizures or fits

• Behavioural or personality changes

• Feeling frequently tired

If you or your child is recovering from encephalitis, you’re not alone. Even with long-term complications, many people go on to have full and active lives. But they might need a bit of extra support or therapy along the way. The truth is that no two cases of encephalitis will have the exact same outcome. Each person can be affected in different ways, but there are different tools and treatments at your disposal.

When should I consider booking an MRI scan?

If you’ve been experiencing persistent symptoms like confusion, seizures, or personality changes, and doctors haven’t yet found a clear cause, an MRI scan could help provide the answers, and crucially, the treatment you need.

MRI scans are especially useful if:

• Your symptoms have developed rapidly or are getting worse.

• You may have a brain infection or inflammation.

• Other tests (like CT scans or blood tests) haven’t been able to help with your diagnosis.

At Scan.com, you can book an MRI brain scan without a referral from your GP. Skip the NHS waiting lists and book a scan near you today. We can help you fast-track your diagnosis and treatment. If you’re not sure whether an MRI scan is the right next step for you, our expert clinicians are on hand to help guide you, with clinical consultations within days. 

Choose from over 150 centres nationwide with flexible appointment times and get fast online results, including a digital imaging report. If anything serious is found, we’ll support you with the next steps. Let us take the stress out of the process, so you can focus on getting answers.

FAQs

Does encephalitis show on an MRI?

Yes, encephalitis often shows up clearly on an MRI scan. MRI is one of the best tools for detecting inflammation in the brain. It can reveal areas of swelling, tissue damage or abnormal signals that suggest an infection or autoimmune response, sometimes even before symptoms become severe.

What does encephalitis look like on an MRI?

On an MRI, encephalitis often shows up as bright or patchy areas in the brain, especially on T2-weighted or FLAIR images. These bright spots are signs of swelling or fluid build-up. In herpes encephalitis, the temporal lobes light up, while autoimmune types might show scattered changes across the brain. But don’t worry about trying to understand your images on your own. At Scan.com you’ll have an expert clinician guide you through them, explaining what the images are showing and what it means.

Is it normal to feel scared or overwhelmed?

Absolutely. Feeling worried, anxious, or uncertain is completely understandable. Brain inflammation sounds serious, and it is, but it’s important to remember that many people recover fully with the right treatment and support.

You don’t need to go through this alone. Your medical team is there to help, and if you need an MRI scan to move things forward, we’re here to help you get referred quickly for the best possible outcomes.

Sources:

Diagnosing and managing acquired brain injury (ABI), including encephalitis, in adults and children. A guide for General Practitioners (GPs). (2021). https://www.encephalitis.info/wp-content/uploads/2023/11/GP-Guide-2018.pdf

Encephalitis. (2023). https://www.nhs.uk/conditions/encephalitis/

Encephalitis. (2025). https://bestpractice.bmj.com/topics/en-gb/436

Herpes simplex encephalitis. (2024). https://radiopaedia.org/articles/herpes-simplex-encephalitis?lang=gb

Jayaraman, K., et al. (2018). Magnetic Resonance Imaging Findings in Viral Encephalitis: A Pictorial Essay. https://pmc.ncbi.nlm.nih.gov/articles/PMC6126294/

Meningitis - bacterial meningitis and meningococcal disease: What else might it be? (2024). https://cks.nice.org.uk/topics/meningitis-bacterial-meningitis-meningococcal-disease/diagnosis/differential-diagnosis/

Returning to school after encephalitis. (2017). https://www.encephalitis.info/wp-content/uploads/2023/11/Returning_to_school._Summary_current_version_2.pdf

Which is Better for Brain Imaging: MRI vs CT Scan? (2023). https://tischbraintumorcenter.duke.edu/blog/which-better-brain-imaging-mri-vs-ct-scan