Electroencephalography (EEG) is the technique of measuring and recording the electrical activity of the brain.
What to Expect
A routine clinical EEG recording typically lasts 60-90 minutes. During this time, it is common to perform different "activation procedures" which may evoke different types of brain activity than is seen during the resting awake state. These activation procedures include sleep, intermittent stimulation with a strobe light, hyperventilation and eye closure.
When a routine EEG is done in a patient with suspected or known epilepsy, often it is to look for abnormal activity resulting from "brain irritability" that shows a possible predisposition to epileptic seizures. The EEG appearance of the onset of the seizure can provide significantly more definitive information about the patient's epilepsy than inter-ictal recordings can in many cases.
This is a continuous EEG monitoring technique. Continuous EEG typically involves the use of a portable EEG machine connected to a patient to look for seizure activity that is not apparent clinically.
Why It Is Done
Various forms of EEG recording can be used in a variety of clinical situations, including:
- 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 characterize seizures for the purposes of treatment
- to localize the region of brain from which a seizure originates for work-up of possible seizure surgery to monitor for non-convulsive seizures