Characteristics of temporal lobe epilepsy with no ictal impairment of consciousness

Introduction

The predominant manifestations of temporal lobe epilepsy (TLE) are partial seizures with impairment of consciousness (type I.B of ILAE classification), although consciousness impairment is not necessary in all seizures of patients with TLE. Nevertheless, there have been very few reports of TLE patients with exclusive seizures with no impairment of consciousness (i.e. isolated auras). The objective of this study was to determine any differential characteristics of this subgroup of TLE patients.

Material and methods

Retrospective case-control study in 163 consecutive TLE patients from our hospital database. The patients were divided between those with and without ictal impairment of consciousness, based on directed semi-structured questionnaire to the patient and relatives and on video–EEG records. Ten independent variables (8 clinical and 2 paraclinical) were compared between the groups.

Results

14 patients (8.5%) formed the “TLE without ictal impairment of consciousness” group. This group was less refractory to medical treatment [Odds Ratio: 0.14 (0.03–0.64); p < 0.01] and had frequent ictal motor behaviour [Odds ratio: 5.33 (1.65–17.14); p = 0.008] and less frequent presence of automatisms [p < 0.001]. Non-significant tendencies were observed for a higher frequency of lesional substrate and fewer generalization episodes.

Discussion

TLE without ictal impairment of consciousness appears to be more frequent than previously thought. This subgroup of TLE patients shows differential characteristics that may possibly result from a differential propagation of the original epileptic activity towards frontal areas rather than towards neocortical and diencephalic structures, which may be related to the more frequent presence of structural lesions.