Interictal Temporal Delta Activity is an Epileptiform EEG Pattern
Abstract number :
2.202;
Submission category :
3. Clinical Neurophysiology
Year :
2007
Submission ID :
7651
Source :
www.aesnet.org
Presentation date :
11/30/2007 12:00:00 AM
Published date :
Nov 29, 2007, 06:00 AM
Authors :
J. Tao1, M. Baldwin1, S. Hawes-Ebersole1, J. S. Ebersole1
Rationale: Interictal temporal delta activity (ITDA) is an EEG pattern commonly observed in patients with temporal lobe epilepsy. Several studies have suggested that it carries a lateralizing and localizing value similar to interictal spikes and is associated with favorable surgical outcome. However, whether ITDA reflects simply structural and metabolic dysfunction or underlying epileptiform activity is unclear. The aim of this study was to characterize the cortical EEG substrates of ITDA and in so doing better understand its biological and clinical significance. Methods: We recorded simultaneously 26 channels of scalp EEG with sub-temporal supplementary electrodes and 46-98 channels of intracranial EEG in 23 presurgical candidates with temporal lobe epilepsy. All subjects had ITDA on scalp EEG. Cortical EEG activity underlying ITDA was characterized in terms of morphology, frequency, and source location. These features were compared to those of cortical spike and seizure discharges in the same patientResults: The cortical EEG substrates of scalp ITDA were typically a mixture of theta/delta slowing and spike and wave potentials. Often the spike component was not recordable on the scalp. The morphology of interictal temporal delta activity was rhythmic in seven (32%) patients and semi-rhythmic or polymorphic in fifteen (68%) patients. The anatomic distribution this cortical activity was similar to that of the patient’s intracranial EEG spikes and seizure potentials. Cortical ITDA was most commonly observed from the mesiobasal and anterior temporal cortices. Rarely was the source in lateral temporal or extra-temporal cortices. Thirteen (59%) patients with ITDA had mesial and mesiobasal temporal seizure onsets, whereas nine (41%) patients had a temporal neocortical seizure origin. Conclusions: Our findings suggest that interictal temporal delta activity is a unique epileptiform EEG pattern reflecting the intrinsic excitability of an epileptic network, rather than simply reflecting focal nonspecific structural and metabolic dysfunction
Neurophysiology