Page 70 - ILAE_Lectures_2015

Figure 3. Upper EEG  Slow spike and wave discharge; lower EEG – fast rhythms.

The causes of LGS remain unclear but are similar to those seen in West syndrome (Table 1),
from which LGS sometimes evolves. Two-thirds to three-quarters of children with LGS have
developmental problems prior to onset of seizures. This reflects the diverse aetiologies
associated with LGS. With the onset of seizures development stagnates and, at times of
particularly frequent seizures, may regress. Nearly but not all children with LGS eventually
have learning difficulties, usually severe, and behavioural problems are also very frequent.
With increasing age some children become seizure free but many continue to have the
phenotype of LGS into adult life or else develop a rather non-specific epilepsy with less
frequent convulsive and non-convulsive seizures. Features which suggest a better prognosis
include cryptogenic or idiopathic in type, more frequent myoclonic seizures, EEGs which
feature some fast spike and/or polyspike and wave discharges, older age of onset and rapid
control of seizures.

LGS is notoriously drug resistant, although some children will respond to AEDs, albeit often
only temporarily. Drugs active against generalised seizures, particularly sodium valproate,
are usually used first. Benzodiazepines and lamotrigine can also be helpful, although the latter
may exacerbate myoclonic seizures. Ethosuximide may help atypical absences in particular.
Drugs such as carbamazepine and phenyotin should be used with particular caution as they
may exacerbate some seizure types. Felbamate, topiramate, lamotrigine and rufinamide have
all been shown in randomised controlled studies to be superior to placebo in LGS and both
levetriracetam and zonisamide are also probably appropriate drugs to try. Non drug
treatments which can be helpful include the ketogenic diet and vagal nerve stimulation. Very
occasionally children develop LGS as a consequence of surgically remediable focal
pathology. Callosotomy has an occasional role to play for the treatment of astatic seizures.

Doose syndrome (also called epilepsy with myoclonic-atonic seizures or epilepsy with myo-
atonic seizures)
This syndrome usually starts between two and four years of age, but can begin as early as the
first year of life or up to mid-childhood. Boys are affected more than girls and development
is normal prior to the onset of seizures. It is now considered to be an idiopathic generalised
epilepsy (IGE).