Temporal intermittent δ activity: a marker of juvenile absence epilepsy?

Abstract

Purpose: To report three cases of juvenile absence epilepsy (JAE) with temporal intermittent, asynchronous delta activity over the temporal regions.

Methods: Long 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.

Results: Among 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.

Conclusion: The 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.