By

T.R.DIVYA

The nervous system is unique in the vast complexity ofthought processes and control actions it can perform.

It receives each minute literally millions of bits ofinformation from the different sensory nerves andsensory organs and then integrates all these todetermine responses to be made by the body.

The Basic Functional Unit of the brain isNEURONS..

The central nervous system contains more than 100billion neurons.

Incoming signals enter this neuron through synapseslocated mostly on the neuronal dendrites, but also onthe cell body.

A special feature of most synapses is that the signalnormally passes only in the forward direction

The ELECTROENCEPHALOGRAM (EEG) is recordingof the electrical activity of the brain from the scalp.

Another name for EEG is brain wave test

The first recordings were made by Hans Berger in 1929.

But similar studies have been done at earlier yearsaround 1870’s in animals.

The wave forms recorded are thought to reflect theactivity of the surface of the brain and cortex.

The brain's cells produce tiny electrical signals when they send messages to each other.

During an EEG test, small electrodes are placed on to scalp.

They pick up brain's electrical signals and send them to a machine called an electroencephalograph.

They records the signals as wavy lines on to a computer screen or paper.

Brain cells communicate with each other by producingtiny electrical signals, called impulses

An EEG measures this activity. The test is done by aEEG specialist in doctor's office or at a hospital orlaboratory.

They will be asked to lie on back on a bed or in areclining chair.

Flat metal disks called electrodes are placed all overscalp.

The disks are held in place with a sticky paste.

The electrodes are connected by wires to a speaker andrecording machine.

The recording machine changes the electrical signalsinto patterns that can be seen on a computer. It lookslike wavy lines.

The patient will need to lie still during the test withtheir eyes closed because movement can change theresults.

Wash hair at night before the test going toperform.

Do not use any oils, sprays, or conditioner on hairbefore this test.

Avoid all food and drinks containing caffeine for 8hours before the test.

Patient may need to sleep during the test.

If so, patient may be asked to reduce their sleeptime the night before.

But to reduce the sleep do not drink any caffeinecontaining material, energy drinks etc..

The electrodes may feel sticky and strange on scalp but should not cause any other discomfort.

Patient should not feel any discomfort during the test.

This procedure is completely painless and can beperformed without shaving any of patient’s hair.

EEG can help diagnose a number of conditions,including epilepsy, sleep disorders and braintumors.

Normal brain waves occur at a rate of up to 30 persecond, but in someone with epilepsy - the EEGmay show bursts of abnormal discharges in theform of spikes and sharp wave patterns.

Sleep disorders (suchas narcolepsy)Head injuriesBrain infectionBrain hemorrhageAlzheimer's diseaseDegeneration of braintissue

Metabolic conditionsthat affect brain tissueHormonal conditionsthat affect brain tissueCertain disorders of thecentral nervous systemStrokeBrain tumorBrain death.

Dementia– a group of symptoms that areresponsible for the decline of brain function.

Vertigo– the sensation that you are movingeven when you are standing still.

Brain abscess – a pus-filled swelling in thebrain that is caused by an infection.

Encephalitis – inflammation of the braintissue that is sometimes caused by an infection.

Cerebral infarct – brain tissue that hasdied due to a blockage in blood flow.

An abnormal EEG doesn't automatically mean thatpatient have epilepsy.

The EEGs of babies and young children can oftenrecord irregular patterns that don't meananything, or the irregularities may flag previouslydiagnosed neurological conditions such as cerebralpalsy.

Abnormal results on an EEG test may be due to:

Abnormal bleeding (hemorrhage)

An abnormal structure in the brain (such as a brain tumor)

Attention problems

Tissue death due to a blockage in blood flow (cerebralinfarction)

Drug or alcohol abuse

Head injury

Migraines (in some cases)

Seizure disorder (such as epilepsy or convulsions)

Sleep disorder (such as narcolepsy)

Swelling of the brain (encephalitis)

The procedure is very safe.

The flashing lights or fast breathing(hyperventilation) required during the test maytrigger seizures in those with seizure disorders.

The health care provider performing the EEG istrained to take care of patient if this happens.