Assessment & Testing
Diagnosis
A possible seizure raises important questions. Diagnosis brings together your account of what happened, medical history, examination and, where appropriate, tests.
About this information: This webpage is subject to continuous review by Epilepsy Ontario to help keep the information current. Updates to linked pages may be in progress. This material is for informational purposes only and should not be used for self-diagnosis or as a substitute for professional medical advice, diagnosis or treatment. Consult your healthcare provider about your own health and care.
First Seizure
Call 911 for a first known seizure or another seizure emergency. Do not use this page to decide whether an episode is safe to ignore.
After urgent care, follow the instructions you receive about further assessment, safety and follow-up. Ask when and how you will see a clinician with expertise in seizures.
Understanding the Process
How is epilepsy diagnosed?
Diagnosis is a clinical assessment, not the result of a single checklist or test. Your healthcare provider considers the whole picture and whether another condition could explain the episode.
Your history & description
What happened before, during and after the episode matters. A witness’s account can be helpful, especially if you do not remember the event.
Examination & investigations
The assessment may include a physical examination, an ECG to check the heart, blood tests, an EEG or brain imaging. The tests recommended depend on the circumstances.
Conditions Mistaken for Epilepsy
Fainting, some heart problems, sleep-related events, migraine and functional / dissociative seizures can resemble epileptic seizures. Some acute illnesses can also cause seizures without meaning that a person has epilepsy.
A healthcare professional must assess the cause. Symptoms alone cannot reliably distinguish these conditions.
Before Your Visit
Preparing for Your Appointment
Bring useful information.
- A description of the episode and any previous similar events.
- A list of medications, doses, supplements and allergies.
- Relevant medical and family history.
- Available hospital reports or previous test results.
- Your questions, concerns and the contact details of your pharmacy.
Record what happened.
- The date, start time and duration.
- What the person was doing beforehand.
- The first change noticed and what happened next.
- Movements, responsiveness and any breathing or colour changes.
- Recovery, memory of the event and any injury.
If a video is available, ask your clinician how to share it securely. Never delay first aid or emergency help to make a recording.
Seizure Record — Original Printable Sheet
The recording sheet remains available. Its older emergency advice includes waiting more than an hour for persistent confusion; do not use that as your emergency threshold. Follow the updated First Aid page and your individual seizure action plan.
Original publication: © Edmonton Epilepsy Association, 2003.
Understanding Investigations
Diagnostic Tests
Not everyone needs every test. Ask what each test is intended to show, how to prepare and how the results will be explained.
Functional Tests: Electroencephalogram (EEG)
An EEG records electrical activity using electrodes placed on the scalp. It can support diagnosis and provide information about seizure type or an epilepsy syndrome.
A normal EEG does not rule out epilepsy. An abnormal EEG does not, by itself, establish the diagnosis. Results must be interpreted alongside the clinical history.
Depending on the situation, further testing may include sleep-deprived, ambulatory or video EEG monitoring.
Imaging Tests: MRI
Magnetic resonance imaging produces detailed pictures of brain structure. Your healthcare team decides whether it is appropriate and explains the safety screening.
Imaging Tests: CT
Computed tomography uses X-rays to produce images. It may be used in particular circumstances, including some urgent assessments or when MRI is unsuitable.
Follow your testing centre’s instructions. Preparation varies by test and person. Do not change medication, sleep, food or fluids based on a general webpage. Ask the centre about implants, medical devices, sedation, accessibility or any concerns.
Specialist Assessment
Additional Tests
Specialist evaluation may involve further investigations, including when considering epilepsy surgery. The team selects tests for the individual; not everyone requires the same combination.
For Adults Undergoing Diagnostic Testing
When Seizures Continue Despite Treatment
Ask about specialist review if seizures continue or the diagnosis remains uncertain. ILAE defines drug-resistant epilepsy around the failure of adequate trials of two appropriately chosen, tolerated and used medication schedules to achieve sustained seizure freedom.
Assessment can identify further options. A referral for surgical evaluation does not mean surgery will be recommended, and outcomes vary.
Helping a Child Prepare
Ask the testing team for an age-appropriate explanation of why the test is needed, what will happen and who can stay with your child. Invite questions and acknowledge worries.
Tell the team about communication, sensory or accessibility needs so they can discuss appropriate support.
Your Healthcare Team
Ask your treating clinician about referral to a neurologist or pediatric neurologist, follow-up and any questions about the diagnosis. Discuss a second opinion if you remain concerned.
Before leaving, make sure you know how results will reach you and whom to contact if events recur.
Other Conditions & Support Needs
Let your team know about other health conditions, development, learning, mood or daily-life concerns. These are part of understanding the whole person and planning appropriate care.
Further reading:
NICE: Diagnosis and assessment ·
ILAE: Drug-resistant epilepsy.
NICE is UK clinical guidance; local referral and testing arrangements differ.
