20 Feb 2026
By the Lampsy Team
Getting a possible epilepsy diagnosis can feel overwhelming. One moment you're trying to make sense of what happened to you and the next, you're sitting in a neurologist's office being handed referral forms for tests you've never heard of. What is an EEG, exactly? Why does your doctor want an MRI? What are all these blood tests for?
If this is where you are right now, you're in the right place.
This guide will walk you through every major epilepsy diagnostic test, what each one is looking for, what the experience is actually like, and what the results can (and can't) tell your medical team.
Why Diagnosing Epilepsy Is More Complex Than It Sounds
Epilepsy is not diagnosed with a single test. This surprises many newly diagnosed patients, who expect a clear "positive" or "negative" result the way you might get with a blood glucose test. Instead, epilepsy diagnosis is a clinical process that combines your personal history, physical examination, and a series of specialized tests to build a full picture.
Part of what makes epilepsy diagnosis complex is that the brain is extraordinarily difficult to study. Seizures are transient events: they begin, end and leave relatively few lasting traces behind. A test performed hours or days after a seizure may show nothing at all, which doesn't mean the seizure didn't happen. It simply means the brain has returned to a baseline state by the time the scan or recording was taken.
That's why neurologists rely on multiple tests together, rather than any single definitive result. Each test answers a different question. And together, they help your doctor determine not just whether you have epilepsy, but what type: a distinction that significantly shapes your treatment plan.
Let's go through them one by one.
The Electroencephalogram (EEG): Reading Your Brain's Electrical Activity
What Is an EEG?
The electroencephalogram, almost always referred to as an EEG, is the cornerstone test in epilepsy diagnosis. It measures the electrical activity of your brain by recording the tiny voltage fluctuations produced by neurons communicating with one another.
The brain never stops producing electrical signals, even during deep sleep. In a healthy brain, these signals follow recognizable patterns that vary predictably depending on whether you're awake, drowsy, asleep, or concentrating. In a brain prone to seizures, those patterns can include abnormal "spikes," "spike-and-wave" discharges, or other irregular activity that a trained neurologist can identify and interpret.
The EEG doesn't hurt. It produces no electrical current, it only records. It is entirely passive, and you'll feel nothing during the procedure itself.
What Happens During an EEG?
When you arrive for your EEG, a technician will measure your head and mark specific spots with a washable pencil or marker. Small metal discs called electrodes are then attached to your scalp using a conductive gel or paste that helps ensure good electrical contact.
Once you're set up, the actual recording begins. A standard outpatient EEG usually lasts between 20 and 40 minutes, during which time the technician will ask you to:
Lie still and relax with your eyes closed (to capture your baseline resting brain activity)
Open and close your eyes on command (to see how your brain responds to visual input)
Breathe rapidly for a few minutes, a technique called hyperventilation, which can provoke abnormal activity in susceptible individuals
Look at a flashing strobe light, another activation technique used to detect photosensitive epilepsy
None of these are dangerous, even if they sound a little intense. The technician will stop any activation procedure immediately if it causes discomfort.
Why You Might Need a Sleep-Deprived or Prolonged EEG
A standard EEG captures only a short window of brain activity, and here's the honest reality: a normal EEG does not rule out epilepsy. Many people with confirmed epilepsy have completely normal interictal EEGs, meaning the recording taken between seizures shows no abnormality at all.
To increase the diagnostic yield, your neurologist may order one of the following variants:
Ambulatory EEG: Electrodes are attached to your scalp, connected to a small portable recorder you wear in a bag or belt pack. You go home and live your normal life for 24 to 72 hours while the device records continuously. If a seizure or unusual event occurs during that window, the recording captures it. This is particularly valuable for people whose suspected seizures happen infrequently or only at night.
Video-EEG monitoring (inpatient): This is the gold standard for epilepsy diagnosis and pre-surgical planning. You're admitted to an epilepsy monitoring unit (EMU), where both your brain's electrical activity and your physical movements are recorded simultaneously on camera. The goal is to capture a seizure event in real time, correlating exactly what's happening electrically in the brain with what's visible externally. Medications may be adjusted to increase the likelihood of a seizure occurring during the monitoring period.
What an Abnormal EEG Actually Means
An abnormal EEG finding doesn't automatically mean you have epilepsy, and a normal EEG doesn't mean you don't. What EEG findings can reveal:
Focal slowing may suggest localized brain dysfunction in a specific region
Generalized spike-and-wave discharges are often associated with generalized epilepsy syndromes
Focal spikes or sharp waves suggest focal (partial) epilepsy originating from a specific brain region
Hypsarrhythmia is a characteristic pattern associated with infantile spasms
Your neurologist will interpret EEG findings in the context of your clinical history and other test results. It is not a test to be interpreted in isolation.
MRI: Looking for Structural Causes of Epilepsy
Why the Brain Needs to Be Imaged
An EEG tells you about electrical activity. An MRI (magnetic resonance imaging) tells you about the brain's physical structure.
In approximately 30–40% of people with epilepsy, there is an identifiable structural abnormality in the brain that is causing or contributing to their seizures. Finding that structural cause is critical because it can:
Confirm the epilepsy diagnosis
Identify the seizure focus (the area of the brain where seizures originate)
Rule out serious underlying conditions like tumors, arteriovenous malformations, or areas of cortical dysplasia
Determine whether the person might be a candidate for epilepsy surgery
Understanding MRI Results
A normal MRI does not rule out epilepsy. Many people have epilepsy with no visible structural cause: this is called non-lesional epilepsy. In these cases, the seizure focus may be too small to detect even with advanced imaging, or the epilepsy may be genetic in origin.
If your MRI reveals a structural abnormality, your neurologist will discuss what it means for your diagnosis and treatment options, including whether surgery might be appropriate.
Blood Tests: Ruling Out Other Causes and Checking Your Baseline
Blood tests alone cannot diagnose epilepsy. What they can do is equally important: rule out other conditions that cause seizure-like episodes, identify metabolic triggers for seizures, check for underlying conditions that affect treatment choices and establish baseline organ function before starting medication.
Living With the Uncertainty of Diagnosis
Here's something no one tells you enough: the diagnostic process for epilepsy can take time. Sometimes a long time.
You might have your EEG, MRI, and blood tests within the first few weeks, review the results with your neurologist, and leave with a clear diagnosis. That's the ideal scenario. But it doesn't always unfold that way.
EEGs are often normal between seizures. MRIs may show nothing definitive. A single seizure may not meet the clinical criteria for epilepsy diagnosis under the most widely used definitions (which generally require either two unprovoked seizures at least 24 hours apart, or one unprovoked seizure with a high probability of further seizures based on the diagnostic findings). In these situations, your neurologist may adopt a "watchful waiting" approach while gathering more information.
This uncertainty can be genuinely distressing. The anxiety of not knowing, of living in a diagnostic limbo, is one of the most commonly reported challenges by people in the early stages of an epilepsy evaluation. If that's where you are, know that it's a recognised and valid part of the process. Seeking support from an epilepsy nurse specialist, patient advocacy organization, or peer support community during this period can make a meaningful difference.
The Role of Nocturnal Seizure Monitoring in the Diagnostic Picture
For many people, particularly those whose suspected seizures happen only during sleep, the diagnostic process is made significantly harder by the simple fact that their events are unwitnessed.
You wake up with a bitten tongue or someone notices you convulsing in the night, but by the time anyone can react, the event is over. Without a witnessed, documented seizure, your neurologist is working with incomplete information. The EEG may not capture it. The MRI may be normal. You're left describing symptoms to a doctor who didn't see them, doing your best to put words to something you may have been unconscious for.
This is where modern seizure monitoring technology is beginning to change the diagnostic landscape.
Lampsy, developed specifically for people living with epilepsy and their families, is an epilepsy monitoring system built into a common lamp. Using privacy-preserving camera technology, it detects over 99% of tonic-clonic seizures and generates 18 times fewer false alarms than traditional monitoring approaches, all without any wearable devices or skin contact.
Lampsy can capture video recordings of abnormal movement events that can then be reviewed later. Rather than describing from memory what you think happened or relying on a partner who may have been half-asleep, you have objective video of the event.
For newly diagnosed patients navigating the uncertainty of the diagnostic period, Lampsy also provides something harder to quantify but just as real: peace of mind. Knowing that if something happens during the night, it will be detected and documented, makes the fear of going to sleep alone a little less acute.
What Happens After the Tests: Understanding Your Results
Once your tests are complete, you'll have a follow-up appointment with your neurologist to discuss the findings. Here's what to expect from that conversation, and how to prepare for it.
Questions to Ask Your Neurologist
Go into your results appointment prepared. Write down your questions beforehand, such as:
What did the EEG show, and what does that mean specifically for me?
Was the MRI normal? If something was found, what is it?
Do my results support an epilepsy diagnosis or is more testing needed?
If I do have epilepsy, what type is it?
What are my treatment options, and what are the first steps?
Are there any triggers I should be actively avoiding?
What should I do if I have another seizure before my next appointment?
What a Formal Epilepsy Diagnosis Means
Receiving a formal epilepsy diagnosis is a significant moment. For many people, there's an unexpected element of relief, finally having a name for what's been happening. There can also be fear, grief and a flood of practical concerns about driving, work, lifestyle, and the future.
All of these responses are valid. Epilepsy is a chronic condition, but it is also one that millions of people manage successfully, since about 70% of people with epilepsy could live seizure-free if properly diagnosed and treated.
Your neurologist will discuss treatment options, most commonly antiseizure medications and help you develop a personalized management plan. If you haven't already, ask about creating a Seizure Action Plan: a written document that outlines exactly what should happen if you have a seizure, including when to call emergency services, what medications you take, and who your emergency contacts are. You can download a fillable template from our Resources Hub.
Frequently Asked Questions
How long does it take to get an epilepsy diagnosis?
There's no single answer. Some people receive a clear diagnosis within weeks of their first seizure. Others go through months of testing and monitoring before a definitive picture emerges. The timeline depends on seizure frequency, test availability, and how clearly the EEG and imaging results support the clinical picture.
Can an EEG detect epilepsy even if I haven't had a seizure recently?
Yes, EEGs can detect interictal (between-seizure) abnormalities like spikes or spike-and-wave discharges that indicate a predisposition to seizures even when no seizure has occurred recently. However, many people with epilepsy have completely normal interictal EEGs, so a normal result doesn't rule out the condition.
Is an MRI always required for an epilepsy diagnosis?
Not always, but it is strongly recommended by most epilepsy guidelines for anyone presenting with new-onset seizures.
What's the difference between an epilepsy diagnosis and a seizure disorder diagnosis?
In medical usage, "epilepsy" and "seizure disorder" are often used interchangeably. However, epilepsy technically refers to a condition involving recurrent, unprovoked seizures. A single seizure caused by a specific, reversible trigger (like very low blood sugar or a fever) is an acute symptomatic seizure, not epilepsy.
Do blood tests show epilepsy?
No, blood tests cannot directly diagnose epilepsy. They are used to rule out metabolic or toxic causes of seizures, check organ function, and establish baselines before starting medication. In some cases, genetic blood tests can confirm a specific genetic epilepsy syndrome.
What if all my tests come back normal?
Normal test results are actually quite common in epilepsy. A normal EEG and a normal MRI do not mean you don't have epilepsy, they mean no structural cause has been found and no interictal electrical abnormality was captured during testing. Your neurologist will combine the test results with your clinical history (including seizure descriptions and their frequency) to reach a clinical diagnosis. Additional monitoring, including ambulatory EEG or video-EEG, may be recommended.
Want to learn more about epilepsy care? Visit the Lampsy Blog for more about articles on epilepsy, nocturnal seizures, management, technology and more. Or explore our Resources Hub for downloadable tools including Seizure Action Plan templates and other guides.
This content is informational only and does not replace medical advice. For medical advice, always consult with your neurologist or epilepsy care team.
