Focal seizures producing loss of wakefulness without ictal asystole: Does temporal lobe syncope exist?

Focal seizures are frequently associated with alteration of consciousness, mainly of awareness, rather than with complete loss of wakefulness. We aimed to explore whether episodes of complete loss of wakefulness (LOW) could be attributed to focal seizures alone, out of the context of ictal asystole or secondary generalization. From a database of adult patients with refractory, focal epilepsy, evaluated for presurgical work-up we searched for patients having the following criteria: (1) focal epilepsy, and (2) transient loss of consciousness, documented in video EEG or/and video SEEG, characterized by an alteration in the level of wakefulness ("syncope like", LOW), with eye closure, hypotonia and non-reactivity state. Patients with motor signs of secondary generalization and patients with non-epileptic psychogenic seizures were excluded. Fifteen patients with transient ictal LOW during focal seizures were found. Among them, 12 patients had ictal asystole. We found 3 patients who had complete loss of wakefulness during focal seizures, without asystole or documented hypotension. In two patients the episodes were provoked by high frequency stimulation of hippocampus and amygdala. The third patient had LOW appearing during a spontaneous temporal lobe seizure. Syncope semiology without ictal asystole can be attributed to temporal lobe seizures but remains an exceptional phenomenon. A crucial clinical requirement is the exclusion of cardiac arrhythmias, especially asystole.