Unilateral continuous subclinical paroxysmal activity: an unusual finding in a patient with recurrent absence status

We report a patient with a history of rare generalised tonic-clonic seizures and recurrent absence status who was diagnosed with a rare variant of idiopathic generalised epilepsy and absence status epilepsy. No other pathology was identified and MRI was normal. During a follow-up of 17 years, we recorded a single unilateral continuous, strictly subclinical, paroxysmal activity which lasted for at least several hours. No control was observed under treatment with phenobarbital, lamotrigine and topiramate. Absence status was aggravated with carbamazepine and generalised tonic-clonic seizures were not controlled with ethosuximide. Total seizure control was only possible with sodium valproate, which caused weight gain, and the patient has remained seizure-free for the past 10 years under 1,000 mg/d valproate and 200 mg/d topiramate. The recorded unilateral, long-lasting, subclinical spike-and-wave discharge is quite unusual for idiopathic generalised epilepsy and, in our opinion, occupies a transitional position between generalised and focal activity.