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associated with induction of absence seizures and absence status epilepticus82,85. The role of
phenytoin is less clear, and perhaps less aggravating; therapeutic concentrations of phenytoin
(and carbamazepine) exacerbate idiopathic generalised epilepsies, particularly those
associated with TA, and may induce valproate and benzodiazepine-resistant absence status86.
These observations are echoed by a well-documented case report of six-week absence status
that improved upon discontinuation of phenytoin87. On the other hand, it is a common
experience (shared also by ourselves) that seizure relapse may occur in patients with well-
controlled idiopathic generalised epilepsy on chronic treatment with phenytoin (as part of a
combination, usually with sodium valproate), when discontinuation or substitution of this drug
is attempted.

A final note is reserved for the apparently unusual, although probably underdiagnosed,
coexistence of IGE and symptomatic focal (temporal lobe) epilepsy, where considerations
determining choice of medical therapy may be contradictory6. Determination of the most
troublesome seizure type (usually these are the partial seizures with or without secondary
generalisation) is clearly the primary diagnostic aim, and is based on clinical and inter-
ictal/ictal EEG criteria (Table 1). Drugs that may have adverse effects on ‘primary’ generalised
seizures such as carbamazepine, vigabatrin and tiagabine should be used with caution and
under close monitoring only if absolutely necessary, while those with a broad spectrum of
antiepileptic effects such as sodium valproate or lamotrigine are more appropriate6.

Conclusion

Optimal management of absence epilepsies, including selection of the appropriate anti-
absence drug (and avoidance of the contraindicated ones), advice on lifestyle restrictions, long-
term planning of treatment, and definition of the likely outcome, relies on the diagnosis not
only of absence seizures but also of possible co-existent myoclonic seizures, or GTCS, or both.
As both response to treatment and long-term prognosis are largely syndrome-related, it is
clinically important to make as precise a syndromic diagnosis as possible, or at least attempt
to form an initial working hypothesis. This is because the diagnosis may not be apparent at
first presentation, and close clinical and electroencephalographic follow-up may be necessary
to complete the final diagnostic jigsaw. For example, a child with newly diagnosed TA does
not necessarily have CAE; other generalised seizures (myoclonic jerks or GTCS or both) may
subsequently appear, and suggest alternative diagnoses such as JAE or JME, forecasting a
different outcome. It is also important to remember that not all generalised epilepsies with
absences can fit into the syndromes of IGE recognised by the ILAE. Treatment-wise however,
one can still work successfully along the lines of the tree diagram (Table 3), taking into account
the type of the associated clinical seizures and their relative preponderance in terms of
frequency and severity.

Recognition of possible triggering factors is also essential for appropriate management.
Photosensitivity is the most important precipitant of seizures in IGE, and its presence in a child
with both spontaneous and photically induced absences would dictate the use of sodium
valproate as first choice and at full therapeutic doses, with clonazepam as a second-line drug.
On the other hand, if only photically-induced absences and other generalised seizures occur,
simple avoidance of stimulus may be sufficient, although in some patients the addition of a
small protective dose of sodium valproate may be necessary.

The therapeutic response should be monitored with successive EEG studies. In children the
evidence from school is also essential. As in other epilepsies, good compliance must be
consistently monitored.