Duration of postictal impaired awareness after bilateral tonic-clonic seizures: EEG and patient characteristics

Objective: Ictal and postictal phenomena that may impact the duration of postictal impaired awareness have not been well studied. Postictal unresponsiveness invariably occurs following bilateral tonic-clonic seizures (BTCS). Bilateral tonic-clonic seizures are a major risk factor for sudden unexpected death in epilepsy (SUDEP). We quantify the effects of seizure characteristics on postictal recovery of awareness following BTCS. Factors include: the total seizure duration, the duration of the tonic phase of a BTCS, presence of postictal generalized EEG suppression (PGES), duration of postictal tonic electromyographic discharge, peri-ictal respiratory dysfunction, patient age, duration of epilepsy, and gender. Methods: Fifty-eight patients admitted to the epilepsy monitoring unit with BTCS were studied. Fortyone had unilateral onset temporal seizures. The remainder had bitemporal onsets, extratemporal onsets, undetermined onsets, or were generalized at onset. Following the first BTCS, time to initial recovery of awareness and its possible association with patient and seizure characteristics as well as peri-ictal respiratory dysfunction were evaluated. The presence or absence of postictal agitation was noted. Results: The severity of respiratory dysfunction and seizure characteristics were not associated with time to initial recovery of awareness. A shorter time to recovery of awareness was significantly associated with a younger age (p = 0.007). Postictal agitation was more common in males (p = 0.023). Significance: Focal seizures may impair awareness by active inhibition of subcortical arousal mechanisms. Focal seizures progressing to bilateral tonic-clonic seizures (BTCS) result in further widespread cerebral dysfunction impacting postictal awareness. MRI studies show accelerated brain aging in patients with temporal lobe epilepsy. Our findings suggest that patient age, as a surrogate marker for the lifetime burden of seizures, results in a progressive worsening in time to recovery after BTCS by an increasing negative impact on networks involved in arousal. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

This study aimed to analyze the effects of seizure characteristics on postictal recovery of awareness following bilateral tonic-clonic seizures (BTCS). The results showed that patient age was an important factor affecting the time to recovery of awareness, with younger patients having a shorter recovery time. Additionally, postictal agitation was more common in males. The study also found that focal seizures may impair awareness by inhibiting subcortical arousal mechanisms. Therefore, age and seizure characteristics play an important role in the recovery of awareness after BTCS.