A simple guide to seizure terminology

In this first aid blog post we’ll look at some of the different terms used to describe seizures and what they mean. 

Tonic – clonic seizuretonicclonic

Tonic means stiffening.  Clonic means jerking. In these seizures the person is both stiff and jerking. The body stiffens and the person usually falls. Typically a period of stiffening lasting about half a minute is followed by jerking, which may last a minute or two in most cases.

Tonic seizure

The body stiffens. This type of seizure is something heralded by a cry because the muscles of the chest wall may also stiffen, causing the air to be pushed out against poorly closed vocal chords.  There is no jerking with a pure tonic seizure.

Clonic seizure

Clonic simply means jerking.  The jerking is usually rhythmical.  It may involve one or both sides of the body.  Eyes, face, limbs and trunk may all be involved in the jerking, depending on the individual seizure.

Myoclonic jerks

There is a sharp jerk of the limbs, typically the upper limbs, but sometimes the lower limbs or whole body may be involved.  Small myoclonic jerks may occur very frequently in the morning and may be associated with apparent clumsiness.  Sometimes myoclonic jerks also increase in the evening when a person is tired.

Atonic drop attacks

Atonic drop attacks are exactly the opposite to tonic seizure all muscle stiffness is suddenly lost and the person crashes to the floor.  In a brief atonic seizure the knees sag, but the person recovers without actually falling.  Injury is quite likely to occur with atonic seizures.

Abscence seizures  

The person ‘switches off’ and may be out of touch for a few seconds, typically 5-10 seconds.  Sometimes this is accompanied by blinking of the eyelids.  If the person is walking he/she does not usually fall, although the body may sag.  The head may nod slightly in some absence seizures.  Each absence seizure usually has a sharp on-set and off-set, but hundreds or thousands of these seizures can occur daily and sometimes they occur so frequently that there is no clear beginning and ending to the seizures.

Complex partial seizure

This is partial seizure that occurs with some impairment of awareness, although the person is not usually completely unconscious.  The person may simply be starting and ‘switched off’ or the seizure may involve automatism’s, which are apparently purposeless movements, such as repeated lip-licking, lip-smacking, swallowing, rubbing, picking or climbing movements.  A variety of other movements may occur.

Simple partial seizure 

This is a partial seizure that occurs while the person is fully aware.  A simple partial seizure may involve funny feelings in the abdomen, head or elsewhere.  It may involve movement, such as twitching of the thumb or the corner of the mouth, sensation or the so called autonomic nervous system, resulting in changes in the heart rate, flushing, perspiring or tummy rumbling.

Aura

An aura is often referred to as a warning of a seizure, but it is actually a type of simple partial seizure.  It typically lasts a few seconds and involves odd sensations, such as funny feelings in the abdomen, strange odours (experienced but not actually present) or flashing lights.  An aura often precedes a more obvious seizure, for example a complex partial seizure.

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