Page 63 - ILAE_Lectures_2015

Chapter 7

Severe paediatric epilepsy syndromes

COLIN D. FERRIE

Leeds General Infirmary, Leeds
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Introduction

Most children who develop epileptic seizure disorders do well. As many as 6070% can
expect to eventually become seizure free either through medication or spontaneous remission.
This chapter concerns those who do not. It deals with those epilepsies which can reasonably
be predicted to follow a severe course, rather than with those which are usually relatively
mild but which can, on occasions, prove more difficult.

The term ‘severe paediatric epilepsy syndrome’ does not have a precise meaning. Other terms
with which it overlaps include:

 Refractory epilepsy
 Drug-resistant epilepsy
 Malignant epilepsy.

In the ILAE’s 2001 Diagnostic Scheme, the term ‘epileptic encephalopathy’ was introduced
and defined as:

‘A condition in which the epileptiform abnormalities themselves are believed to
contribute to the progressive disturbance in cerebral function’.

In the 2010 reorganisation1 severe paediatric epilepsy syndrome was recognised as a concept
that could be applied to any form of epilepsy, but there was recognition that children with
some epilepsy syndromes were more at risk than others, and it is these epilepsies that may be
referred to as epileptic encephalopathies. Most of the conditions discussed in this chapter are
epileptic encephalopathies, hence they are characterised not only by parmacoresistant
epileptic seizures, but also with an expectation that children will develop other problems,
including learning difficulties, behavioural problems (including autistic behaviours) and
sometimes physical problems such as ataxia. The concept implies that if epileptic activity can
be controlled, these other problems will be minimised. Some of the disorders discussed, such
as Ohtahara and Dravet syndromes, always behave as epileptic encephalopathies. Others,
such as West and Lennox Gastaut syndromes usually do, while others, such as Doose
syndrome, often do but quite frequently do not.

The epileptic encephalopathies are not neurodegenerative disorders in the usual meaning of
that term. We will not therefore be considering conditions such as the cerebral lipofuscinoses
(‘Batten Disease’).

What makes an epilepsy severe?

We do not know the answer to this question. Almost certainly it has something to do with
aetiology. Until recently, ‘idiopathic’ was often equated with ‘mild’ or ‘benign’ and
‘symptomatic’ with ‘severe’. Also, it was felt likely that epilepsies caused by ion channel
disorders would be relatively mild. It is now clear that these are huge oversimplifications.