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CRMA
Functional testing · Brain activity

Electroencephalo­graphy (EEG)

A recording of the brain's electrical activity through electrodes placed on the scalp. A painless exam with no radiation. At CRMA we perform standard, sleep and paediatric EEGs.

Duration30–60 min
EquipmentEEG machine
ContrastNo
PreparationSpecific
Electroencephalogram (EEG) at CRMA, in Faro: a child wearing an electrode cap while the brain's electrical activity is recorded on the monitor.
In summary

An electroencephalogram (EEG) records the brain's electrical activity through electrodes on the scalp — it is painless, involves no radiation and sends no current into the body. At CRMA, in Faro, we perform standard, sleep and paediatric EEGs, usually lasting 30 to 60 minutes.

What does an EEG assess?

The EEG picks up and records the brain's electrical rhythms, helping the doctor assess changes in how the brain is working. At CRMA we perform:

  • Standard EEG — a recording while awake, at rest, with activation procedures when indicated (opening and closing the eyes, deep breathing, light stimulation).
  • Sleep EEG — a recording that includes a period of sleep, useful when the doctor needs to assess brain activity while falling asleep and asleep.
  • Paediatric EEG — adapted to the child's age, with a parent present.

When it is requested

  • Episodes of loss of consciousness or fainting being investigated.
  • Suspected epilepsy and follow-up as directed by the neurologist.
  • Changes in behaviour or development, in childhood, when requested by the doctor.
  • Sleep disorders, as part of a specialist assessment.

What the exam is like

  • 1Before

    Reception

    Arrive with your referral and with your hair washed and dry, with no products in it.

  • 2

    Placing the electrodes

    The technician places the electrodes on the scalp with a conductive paste — there are no needles and no current passing into the body.

  • 330–60 min

    Recording

    You stay seated or lying down, with your eyes closed, in a calm setting. Activation procedures may be carried out; in a sleep EEG, the recording includes a period of sleep.

  • 4

    Finishing up

    The electrodes are removed and the paste comes off with a simple hair wash. No restrictions after the exam.

Preparation

  • Hair: washed and dry, with no gel, hairspray, oils or tight braids.
  • Meals: have a light meal before the exam — do not come after a long fast.
  • Regular medication: continue as usual, unless your referring doctor advises otherwise.
  • Sleep EEG (sleep deprivation): for adults, sleep no more than 5 hours the night before (go to bed as late as possible and get up as early as possible); for children, go to bed as late as possible and wake as early as possible.
  • Children: bring a comfort object; a parent's presence is welcome.

Results

The recording is carried out by a qualified professional and the report is written by a neurologist. It is available as a PDF (by email or printed) and, with written authorisation, can be sent directly to your referring doctor.

Frequently asked questions

About the EEG.

Does the EEG hurt? Does current pass into the head?

No. The electrodes only pick up the electrical activity that the brain produces naturally — they send no current. It is a painless exam.

How long does it take?

Usually between 30 and 60 minutes; a sleep EEG may take longer, as it includes the period of falling asleep.

Why do I have to come with my hair washed?

Traces of gel, hairspray or oiliness make it harder for the electrodes to make contact and affect the quality of the recording.

What are activation procedures?

They are simple manoeuvres — opening and closing the eyes, breathing deeply, stimulation with a flashing light — that help bring out changes which do not appear at rest. They are carried out only when indicated.

Can my child have an EEG?

Yes. The paediatric EEG is adapted to the child's age and parents can be present during the exam.

Should I stop my medication before the EEG?

No, unless the doctor who requested the exam expressly says so. If in doubt, check when you book.

Ready to book?

Book your EEG at CRMA.

In Faro, with personal service in PT, EN and FR. We'll confirm your booking with you during working hours.