ُElectrodiagnostic study

ELECTROENCEPHALOGRAPHY (EEG)
is typically a non-
invasive method to record electrical activity of the brain along the scalp. EEG measures voltage fluctuations resulting from ionic current within the neurons of the brain. In clinical contexts, EEG refers to the recording of the brain s spontaneous electrical activity over a period of time, as recorded from multiple electrodes placed on the scalp.

Head cap
Hens Berger
1st EEG record
Medical use
?A routine clinical EEG recording typically lasts 20–30 minutes (plus preparation time) and usually involves recording from scalp electrodes. Routine EEG is typically used in the following clinical circumstances:
•to distinguish epileptic seizures from other types of spells, such as psychogenic non-epileptic seizures, syncope (fainting), sub-cortical movement disorders and migraine variants.
•to differentiate "organic" encephalopathy or delirium from primary psychiatric syndromes such as catatonia
•to serve as an adjunct test of brain death
•to prognosticate, in certain instances, in patients with coma
•to determine whether to wean anti-epileptic medications
?The normal Electroencephalography (EEG) varies by age. The neonatal EEG is quite different from the adult EEG. The EEG in childhood generally has slower frequency oscillations than the adult EEG.
?EEG can be recorded either during sleep or during wakefulness.
Sleep
Wave patterns
?Delta wave
is the frequency range up to 4 Hz. It tends to be ?the highest in amplitude and the slowest waves. It is seen normally in adults in slow wave sleep. It is also seen normally in babies. It may occur focally with subcortical lesions and in general distribution with diffuse lesions, metabolic encephalopathy hydrocephalus or deep midline lesions. It is usually