Temporal intermittent delta activity: A marker of juvenile absence epilepsy?

PurposeTo report three cases of juvenile absence epilepsy (JAE) with temporal intermittent, asynchronous delta activity over the temporal regions.MethodsLong term video-EEG using the international 10/20 system and supplementary anterior-inferior temporal electrodes. Cohort of 1123 patients included in our active file seen at least one time over one year.ResultsAmong 23 patients with JAE (2% of our active file), temporal intermittent rhythmic delta activity (TIRDA) was observed in 3 (13%). Moreover, this activity was never observed in 80 patients with juvenile myoclonic epilepsy. None of the three patients had inadequate antiepileptic drug for idiopathic generalized epilepsy. Case 1 had no antiepileptic drug. Case 2 was treated with valproate (1000 mg/day) and case 3 with levetiracetam (1500 mg/day). These delta activities were activated by hyperventilation and drowsiness. They decreased in NREM sleep and reappeared in REM sleep. The frequency was around 3 Hz. These changes were not frequently recorded in any given patient.ConclusionThe presence of TIRDA in the clinical and EEG context is very suggestive of JAE as posterior delta waves are of childhood absence epilepsy but with a more anterior location over the temporal lobe. This pattern was not described before probably because in this easily diagnosed and treated type of IGE, few patients have long-term video-EEG and also because a wrong diagnosis of focal epilepsy can be made. This pattern must be known to avoid the risk of treating this epilepsy by inappropriate antiepileptic drugs.