Lack of aura experience correlates with bitemporal dysfunction in mesial temporal lobe epilepsy

Abstract

The diagnostic value of lack of aura experience in patients with temporal lobe epilepsy (TLE) is unclear. Purpose: To evaluate possible factors of bitemporal dysfunction in patients with mesial TLE who did not experience an aura in electroencephalography EEG/video monitoring for epilepsy surgery. Methods: Ictal scalp EEG propagation patterns of 347 seizures of 58 patients with mesial temporal lobe sclerosis or non-lesional mesial TLE, interictal epileptiform discharges (IED), presence of unilateral mesial temporal lobe sclerosis in visual magnetic resonance imaging (MRI) analysis, prose memory performance, history or not of an aura, and postictal memory or absence of an aura were analyzed. The ictal EEG was categorized as follows. EEG seizure: (a) remaining regionalized, (b) non-lateralized, (c) showing later switch of lateralization or bitemporal asynchronous ictal patterns. Results: Absent aura in monitoring was significantly correlated with absence of unitemporal MRI sclerosis ( P=0.004), bitemporal IED ( P=0.008), and propagation of the ictal EEG to the contralateral temporal lobe ( P=0.001). Other historical data and interictal prose memory performance were not significantly correlated with absent aura. Ten of 11 patients without aura in monitoring also had absent or rare auras in their history. Conclusions: Lack of aura experience strongly correlates with indicators of bitemporal dysfunction such as bitemporal interictal sharp waves and bitemporal ictal propagation in scalp EEG, and absence of lateralized MRI sclerosis in patients with mesial TLE. The fact that absent auras are not correlated with episodic memory suggests a transient memory deficit, probably because of rapid propagation to the contralateral mesial temporal lobe.