Epilepsy and its types


Epilepsy is a brain disorder characterized by convulsive seizures or loss of consciousness or both.

Convulsion and Convulsive Seizure

Convulsion refers to uncontrolled involuntary muscular contractions. Convulsive seizure means sudden attack of uncontrolled involuntary muscular contractions. It occurs due to paroxysmal (sudden and usually recurring periodically) uncontrolled discharge of impulses from neurons of brain, particularly cerebral cortex.


Patient affected by epilepsy is called epileptic. The person with epilepsy remains normal in between seizures. Epileptic attack develops only when excitability of the neuron is increased, causing excessive neuronal discharge.


Epilepsy is divided into two categories:

1. Generalized epilepsy

2. Localized epilepsy.


Generalized epilepsy is the type of epilepsy that occurs due to excessive discharge of impulses from all parts of the brain. It is also called general onset seizure or general onset epilepsy.

Generalized epilepsy is subdivided into three types:

1. Grand mal

2. Petit mal

3. Psychomotor epilepsy.


Grand mal is characterized by sudden loss of consciousness, followed by convulsion. Just before the onset of convulsions, the person feels the warning sensation in the form of some hallucination. It is called epileptic aura.

Convulsions occur in two stages:

a. Tonic stage

b. Clonic stage.

Tonic Stage

Initially, seizure is characterized by tonic contractions of muscle leading to spasm. Spasm causes twisting facial features, flexion of arm and extension of lower limbs.

Clonic Stage

Clonic convulsions develop after the tonic stage. This stage is characterized by violent jerky movements of limbs and face due to alternate severe contraction and relaxation of muscles.

At the end of attack, alternative tonic and clonic convulsions are seen. During the entire period of

seizure, tongue may be bitten. Electroencephalogram (EEG) shows fast waves with a frequency of 15 to 30 per second during tonic stage. Slow and large waves appear during clonic phase. After

the attack, slow waves are recorded for some time. In between seizures, EEG shows delta waves in all types of epileptics.

Causes of Grand Mal

Cause of grand mal epilepsy is the excess neural activity in all parts of brain. Cause for stoppage of

attack is neuronal fatigue. Factors which accelerate the neural activity resulting in grand mal epilepsy are:

i. Strong emotional stimuli

ii. Hyperventilation and alkalosis

iii. Effects of some drugs

iv. Uncontrolled high fever

v. Loud noises or bright light

vi. Traumatic lesions in any part of brain.


In this type of epilepsy, the person becomes unconscious suddenly without any warning. The unconsciousness lasts for a very short period of 3 to 30 seconds. Convulsions do not occur. However, the muscles of face show twitchlike contractions and there is blinking of eyes. Afterwards, the person recovers automatically and becomes normal. Frequency of attack may be once in many months or many attacks may appear in rapid series. It usually occurs in late childhood and disappears completely at the age of 30 or above. EEG recording shows slow and large waves during the attack. Each wave is followed by a sharp spike. This

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