Paediatrics: Seizures and childhood epilepsies

Seizures and childhood epilepsies

One per cent of children will have had one seizure, not associated with fever, by the age of 14yrs. The majority of these seizures will be general-ized tonic–clonic episodes.

Forms of epilepsy

The two main forms of epilepsies can be categorized as having generalized or focal seizures.

Generalized seizures

These can be described as follows:

·Myoclonic: with shock-like movement of one/several parts or the whole body.

·Tonic: with sustained contraction and stiffness.

·Clonic: with rhythmic jerking of one limb, one side, or all of the body. (See how this contrasts with the description of psychologically determined clinical events,).

·Tonic–clonic: a combination of the above forms.

·Absence: these are episodes of abrupt psychomotor arrest lasting 5–15s in younger children, but can be longer in the older child. They can be associated with retropulsion of the head, upward deviation of eyes and eyelid, or perioral myoclonia. (You should note that facial myoclonia can be asymmetrical and give the impression of a ‘focal’ seizure).

Focal seizures

These seizures start in one area of the brain and then may spread, and ultimately generalize. If the latter part of the event is witnessed it may be described incorrectly as being primarily generalized. The semiology depends on the locality of the initial electrical activity. ‘Typical’ seizure semiology includes the following:

·Occipital: multicoloured bright lights spreading from one area of homonymous visual fields.

·Centroparietal: sensorimotor phenomena spreading from one limb and marching up one side of the body.

·Temporal: feelings of gastric discomfort, strangeness, anxiety, memory disturbances (e.g. familiarity, ‘déjà vu’), autonomia (e.g. automatisms such as nose rubbing), and contralateral clonic or dystonic movements.

·Frontal: dystonic posturing and strange guttural noises.

Status epilepticus (StE)

·  StE can be convulsive with tonic/clonic movements. Alternatively, it can be non-convulsive with impairment of consciousness and often subtle twitch-ing. Technically, StE is a seizure lasting for more than 30min, or repeated seizures lasting more than 30min without recovery of consciousness in between. Practically, though, the treatment algorithm for StE can be used once a convulsive seizure has lasted longer than 5min.