• Records the brain’s own electrical activity through small discs on the scalp
• Painless. Nothing goes into the body and no electricity goes in
• The single most useful test in epilepsy

On the day

• Clean, dry hair with no conditioner or gel
• Take medications as usual
• Breathing fast and flashing lights may be used to bring out patterns

Sparks (between seizures)

Brief spikes that show the brain has a tendency to seize, and where. Most EEGs catch sparks, not seizures.

Fire (a seizure)

A build-up of rhythmic activity that grows, changes and then stops. Catching one is the most direct proof.

Focal: sparks in one area (here, the right temporal region)

Generalized: a discharge across both sides at once

• About half of people with epilepsy have a normal first EEG
• Sparks come and go. A 30-minute recording may simply miss them
• Repeating the test, or recording sleep, increases the chance of finding them
• An abnormal-looking EEG is also interpreted carefully, alongside the story

• Electrodes stay on for 1 to 3 days with a small recorder
• Sleep in your own bed and go about most activities
• Some systems add a home video camera
• Keep a log of events. Press the event button if there is one

Useful when

• Events happen often, or only in certain situations
• A routine EEG did not give a clear answer

• A hospital stay of a few days with continuous video and EEG
• Medications may be lowered, under close watch, to capture a typical event
• Nurses trained to respond to seizures are always nearby

Answers questions like

• Are these events seizures?
• What type, and how often?
• Exactly where do they start? (a key step before surgery)

• Detailed pictures of brain structure using magnets and radio waves. No radiation
• An epilepsy-protocol MRI, ideally at 3 Tesla, looks for subtle changes a routine scan can miss
• 45 to 75 minutes, loud, must lie still
• Young children often need sedation
• Tell the team about any metal or implanted devices

• Hippocampal sclerosis: scarring in a memory structure of the temporal lobe
• Focal cortical dysplasia: a patch of brain that developed differently
• Old injury: stroke, bleeding, low oxygen
• Tumours and blood vessel malformations

Many people with epilepsy have a normal MRI. Medications work just as well, and the diagnosis rests on the story and the EEG.

Medication levels

• Not needed at every visit
• Helpful for side effects, missed doses, pregnancy and drug interactions
• Usually drawn just before the next dose

Safety checks

• Blood counts, liver, kidney, sodium
• Bone health scans with some long-term medications

Who is it most useful for?

• Seizures starting in infancy or early childhood
• Epilepsy with developmental delay, autism or intellectual disability
• No cause found on MRI
• Seizures not responding to medication
• A strong family history

A blood or saliva sample. Results take weeks to months.

Possible results

• Positive: a cause is found. It can guide treatment, for example avoiding certain medications in Dravet syndrome
• Negative: no cause found yet. Data can be re-checked in a few years
• Uncertain (VUS): a change we cannot interpret yet. Not a diagnosis

Genetic counselling before and after testing helps.

After two medications have not worked, the epilepsy center asks:

1. Where do seizures start?
2. Can that area be safely treated?
3. Where are speech, memory and movement?

The whole team reviews every test together, including memory and thinking (neuropsychology) testing. The more the tests agree, the more confident we are.

PET uses a small amount of a sugar tracer. Done between seizures.

SPECT needs an injection within seconds of a seizure starting, so it is done in the EMU.

MEG measures the tiny magnetic fields from brain activity. Like EEG, but less blurred by the skull. No needles, no radiation.

Functional MRI maps language and movement while you do simple tasks in the scanner.

• Thin wires placed inside the brain through tiny openings, under anesthesia
• Records for about 1 to 2 weeks in the EMU
• Can also map function by gently stimulating each contact
• Used when other tests point to an area but not clearly enough to plan surgery

• Your description and a phone video are the foundation
• EEG is the key test. A normal EEG does not rule out epilepsy
• An epilepsy-protocol MRI looks for a cause. A normal MRI is common
• Genetic testing can explain the cause and sometimes change treatment
• When medications are not enough, advanced tests can open the door to surgery
• Ask what question each test is meant to answer