Seizure classification

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As we have mentioned previously, epileptic seizures can be classed into two types, partial focal and generalised. In partial seizures, although just one part of the brain Is affected, there are different types of partial seizures.

Simple partial seizures may cause jerking motions or hallucinations, but the person often remains aware of what is happening. On the other hand, complex partial seizures can cause people to wander, mumble, smack their lips or fumble with their clothes and these would be examples of automatisms.

Whilst partial seizures affect a pinpointed place in the brain, generalised seizures affect, as the name suggests, generally a larger area, or even all of the brain and this usually causes complete unconsciousness. Due to the electrical disturbances being over a larger area of the brain, there are also more different types of generalised seizure compared to types of partial focal seizure.

The six main types of generalised seizure are: Absence, Myoclonic, Clonic, Atonic, Tonic and Tonic-Clonic.

Let’s look at these in a bit more detail:

Absence seizures cause a brief loss of consciousness, sometimes accompanied by localised automatic movements. Whilst some can last hours, they can also only last a few seconds.

Myoclonic seizures usually affect the muscles and the person normally remains conscious. Whilst they only normally last a few seconds, myoclonic seizures have been seen to occur close together, giving the impression of one long seizure. A series of myoclonic seizures can last up to a few hours and commonly, myoclonic seizures happen soon after waking up, or as the person is falling asleep.

Atonic seizures cause the affected person to lose all the tone of their muscles suddenly, and they will fall heavily to the ground and go limp. Recovery can be very quick, but the seizure can come about instantly, but it's important to note that head and facial injuries can be very common to people who have atonic seizures.

Tonic seizures cause the tone of all muscles to suddenly increase, and the person will appear to stiffen. Like in some other types of seizure, if the person is standing up, they will probably fall to the ground.

In Clonic seizures, all limbs will begin to convulse and then the person will fall heavily to the floor. However, unlike other types of seizures, the person will not stiffen first. Therefore we know that the person falls to the floor not due to a change in muscle tone, but because of the convulsing limbs.

Finally, Tonic-Clonic seizures are a combination of tonic and clonic seizures, as the name suggests. Initially, the muscle tone dramatically increases and the person becomes stiff and will fall to the ground. This is the tonic part of the seizure. After this, all of their limbs begin to convulse rhythmically and this is arguably the most iconic type of epileptic seizure, and commonly occurs during sleep. Neither the body nor the limbs should not be restrained during any type of clonic seizure, as this can cause serious damage to both the person having the seizure and possibly the person attempting to restrain the limbs.