EEG is a recording of the electrical activity of the brain using electrodes placed on the scalp. It amplifies brain activity millions of times to detect normal wave patterns like alpha and beta activity in awake patients, and spindle activity during sleep. Abnormalities include slow wave activity indicating severity, epileptiform sharp waves or spikes, and signal suppression. EEG is used to diagnose seizure disorders, evaluate transient spells, detect intracranial diseases like tumors, and assess diffuse brain issues including comas and brain death.

1. 1. Electroencephalography
Definition
- EEG is a surface recording of the electrical activity of nerve cells of the brain
- Electrode placement (10 / 20 – System, international)
- Electrodes are connected with electroencephalograph, which amplifies
the brain activity a million times record it on a strip of paper or stores it
electronically.

2. Main Types of Waves in EEG

3. EEG of a normal awake person consists
alpha and some low amplitude beta activity:

4. During normal sleep EEG consists
spindle activity (10 – 14 Hz)

5. EEG – abnormalities:
- Slow wave abnormalities  the slower, the more severe
is the abnormality
- Epileptiform activity  sharp waves, spikes, spike and waves
- Suppression of activity  attenuation or absence of activity

6. Indication for EEG:
• Seizure disorders (Location of the focus, type of seizure
disorder)
• Evaluation of transient spells (Transitory Ischemic Attack TIA,
Residual Ischemic Neurological Deficit RIND, Completed
Infarction / Syncope or hysterical episodes)
• Intracranial disease process (tumor, abscess)
• Diffuse disturbances of cerebral function (metabolic
disorder, encephalitis, and degenerative process, eg.
v.Creutzfeldt - Jakob disease)
• Coma (status epilepticus, drug overdose, hepatic coma)
• Brain death (ceased activity)

7. Intracranial Causes:

8. Extracranial Causes

9. Simple Partial Seizures

10. Complex Partial Seizures

12. Epileptic potentials

14. Epileptic Focus

15. NMDA = N-methyl – D – aspartate
AMPA = α – amino – 3 – hydroxy – 5 – methylisoxazole – 4 – propionate