Page 451 - ILAE_Lectures_2015

Chapter 46

Presurgical evaluation and outcome of epilepsy surgery in
childhood

J. HELEN CROSS

UCL Institute of Child Health, Great Ormond Street Hospital for Children NHS Trust,
London, and Young Epilepsy, Lingfield

Introduction

Surgery in the management of children with epilepsy is not new. Murray Falconer, a
neurosurgeon at the Maudsley Hospital, recognised that children as well as adults may benefit
from resective surgery, but the age range of his patients did not include the very young1.
Traditionally, focal seizures have been more difficult to diagnose in the young child, both
clinically and electrographically, and a focal onset to seizures may not be readily apparent.
However, the advent of magnetic resonance imaging (MRI), with the increased detection of
structural focal brain abnormality, has opened up the possibility of surgery at an earlier stage
in the natural history of childhood epilepsy.

Selection criteria

There are several points to discuss when considering whether surgery may be more beneficial
earlier rather than later. Many adults presenting for resective surgery have a history of
seizures arising from early childhood, and have been through multiple antiepileptic drugs
(AEDs). Prior to the recognition of different types of epilepsy there was concern that children
may ‘grow out’ of epilepsy but with the use of the classification of the epilepsies the
syndromes with a relatively good prognosis can now be recognised at an early stage, and
when these have been excluded the focal epilepsies are among the most drug resistant.
Chronic epilepsy is not without psychosocial morbidity however; the Oxford study of 100
children with temporal lobe epilepsy demonstrated that at least one-third were not leading an
independent life in adulthood2. Early surgery may therefore reduce the morbidity associated
with frequent seizures through the teenage years.

There are specific issues related to children that need to be considered in the discussion of
the early surgical treatment of epilepsy. The definition of ‘medically intractable epilepsy’ in
adult practice is often defined as epilepsy which has not responded to at least three AEDs
over at least a three-year period. Although in the older child attending normal school this may
have relevance, in the young child experiencing recurrent seizures, and where compromise
to developmental progress has been demonstrated, it is likely that a greater number of drugs
will have been tried over a lesser period of time. Perhaps the most appropriate definition of
intractability in children is ‘inadequate seizure control in spite of appropriate medical
therapy’ with no particular timescale. This has been addressed in the recent ILAE report on
drug resistance, where drug-resistant epilepsy is now defined as ‘a failure of adequate trials
of two tolerated and appropriately chosen and used AED schedules, whether as
monotherapies or in combination, to achieve sustained seizure freedom’3.

The whole issue of what is ‘intractability’ in childhood remains a question for debate, and we
lack tools for prediction of prognosis. We know from epidemiological studies that poor
prognostic indicators are early onset of seizures, poor response to first-line medication, focal