Electroencephalogram

Electroencephalogram or EEG is the used for recording the activities of the brain. It is not painful. In EEG, the electrodes placed on the scalp of the patient records the electrical signals emitted by the brain cells. These are recorded on a computer or a paper. The normal time taken for completion of the EEG test is half an hour to forty-five minutes. There are no side effects associated with EEG, usually.

The electrical activity that has been recorded helps in the diagnosis of numerous conditions like epilepsy. The investigation of various conditions affecting the brain like brain tumours, haemorrhage as well as head injuries are also done using EEG.

If any part of the brain is not functioning properly, the EEG records that also. In patients who are in coma, EEG helps in determining the level of functioning of the brain.

Necessity of doing an EEG

Epilepsy

Epilepsy is the medical condition where brain functions abnormally causing seizures, which are otherwise, called the epileptic fits. When the nerve cells of the brain find it difficult for the effective transmission of the messages, it results in epileptic fits. EEG can be used for the diagnosis of epilepsy.

The signals that are recorded in the computer by the EEG helps the identification of epilepsy type as well as the triggers of epileptic fits or seizures. This will help the doctor in prescribing the appropriate medication for the condition.

In certain cases, people having epilepsy will have to undergo the surgical removal of the fits’ causing tissues from the part where the brain is damaged.

Coma

EEG helps to identify if the person in coma has a brain damage which can be corrected to bring him to condition where he can live with the help of machines that will support life. If the person is brain dead according to EEG, then the machine supporting life will be removed.

EEG can also be used for the diagnosis of various other conditions like:

• Injury to the head
• Dementia
• Vertigo
• A faint known as syncope
• Tumour in the brain
• Abscesses in the brain
• Inflammation of the brain or encephalitis
• The death of the brain tissue due to the flow of blood getting blocked known as cerebral infarct
• Sleeping disorders

How is EEG done

Silver coated electrodes about twenty in number will be attached to the scalp using jelly that is conductive. Then the activity of the brain is recorded for about half an hour. The patient will be asked to hyperventilate.

Once the recording is completed, the person will be subjected to light flashes of varying intensity to check the reaction of the brain towards light. High intensity light can cause seizures in people who display high sensitivity to light.

The signals are then recorded on a video or computer for further analysis.

Results

In normal cases, a negative result means that the brain is working normally. But in certain cases, the EEG records a false negative result, even if the brain is abnormally functioning.

A positive result is the indication of an abnormal functioning of the brain.