Seizure types in children (tonic-clonic, myoclonic, atonic)

What it is

Seizures are divided first into partial and generalized. A partial seizure is simple partial when there is no loss of consciousness and complex partial when there is, and a partial seizure may also carry on as a partial seizure with secondary generalization. Generalized seizures divide into the nonconvulsive, which is the absence seizure, and the convulsive: tonic, myoclonic, clonic or tonic-clonic. The same split is also given the other way round: a generalised seizure is one whose discharge arises from both hemispheres, and may be absence (petit mal), myoclonic, tonic, tonic-clonic (grand mal) or atonic, while a focal seizure arises from one or part of one hemisphere.

How it presents

The tonic-clonic seizure is the convulsive generalized form.

Myoclonic seizure:

Brief, often repetitive, jerking movements of the limbs, neck or trunk.
Seen physiologically in hiccoughs, which are myoclonus of the diaphragm, and on passing through stage II sleep, which is sleep myoclonus.
Consciousness and memory are not impaired.
It may cause a child to spill or drop what he or she is holding, or to fall from the chair.

Atonic seizure:

Sudden loss of muscle tone.
Without warning the child abruptly loses consciousness, collapses and falls to the floor.
No convulsion.
After a few seconds the child regains consciousness and can stand and walk again.
Usually no postictal confusion.
A very brief one may cause only a quick head drop or nodding movement, while a longer one will cause the child to collapse.

A focal seizure can be placed by the lobe it arises from. Temporal lobe seizures, the most common of all the epilepsies, give strange warning feelings or an aura with smell and taste abnormalities and distortions of sound and shape, the aura being visceral, olfactory or auditory; lip-smacking, plucking at one's clothing and walking in a non-purposeful manner are the automatisms that follow spread to the pre-motor cortex, and the intense feelings of having been, or never having been, in the same situation before belong to the same lobe. Frontal seizures involve the motor or premotor cortex and may give movements that travel proximally, the Jacksonian march, with asymmetrical tonic seizures that can be bizarre and hyperkinetic. Occipital seizures give visual hallucinations, gaze déviation and cortical blindes, and parietal lobe seizures give sensory symptoms such as paraesthesia and pains, dyslexia, sensory aphasia, contralateral dysesthesias, that is altered sensation, and a distorted body image.