What is Electroencephalography (EEG)

EEG provides evidence of brain functions.
 

Electroencephalography (EEG) measures electrical brain waves. Brain cells communicate by producing tiny electrical impulses. In an EEG, electrodes are placed on the scalp over multiple areas of the brain to detect and record patterns of electrical activity. Measuring brain activity has many applications.

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Widely used in diagnosing neurological disorders.
 

An EEG can tell us if there is abnormal electrical activity in the brain and, in some cases, the types of seizures you might be going through. One of the most common EEG applications is to show the type and location of the activity in the brain during a seizure. This information can then be used for making the right diagnosis. Beside seizures, an EEG is also used to evaluate people who have problems associated with brain functions. Problems like these may include difficulty with memory, coma, tumors, or weakness of specific body parts (as seen in stroke).

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“Routine EEG” - So called routine EEG recording typically lasts 20–30 minutes. This usually involves recording from many scalp electrodes. Routine EEG is normally used in clinical circumstances where short measurement is sufficient (for example, distinguishing epilectic seizure from other types of seizures or to evaluate coma).

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“Long term EEG” - Sometimes a routine EEG does not provide enough time for analysis.  This most often occurs when specific symptoms occur intermittently and recording the EEG during these events is required.  Long term EEG can be accomplished using Ambulatory EEG equipment (similar to a Holter monitor for recording long term ECG activity).  Electrodes are applied in the office and patients are then sent home for a few days and then return to remove the equipment for analysis.  The other long term EEG monitoring technique is with in-hospital simultaneous long term EEG and clinical video recordings, which requires hospital admission for several days.  These long term EEG monitoring techniques are useful to capture symptoms to see if these events are actually epilepsy related and where in the brain they may originate."