Prognosis of status epilepticus (SE): Relationship between SE duration and subsequent development of epilepsy

In animal models, SE duration is related to epileptogenesis. Data in humans are scarce, mainly in NCSE; therefore, we aimed to study the prognosis of SE de novo and which factors may influence subsequent development of epilepsy.

We evaluated patients with SE without previous epilepsy at our hospital (February 2011-February 2014), including demographics, etiology, number of AEDs, duration of SE, mortality, and occurrence of seizures during follow-up.

Eighty-nine patients were evaluated. Median age was 69 (19-95) years old. Among them, 33.7% were convulsive. Regarding etiology, 59 were considered acute symptomatic (41 lesions, 18 toxic-metabolic), 17 remote or progressive symptomatic, and 13 cryptogenic. The median recovery time was 24h (30 min-360 h). In-hospital mortality was 29% (n = 26). After a median follow-up of 10 months, 58.7% of survivors (n = 37) showed seizures. Subsequently, we analyzed which factors might be related to the development of epilepsy, and we found that epilepsy development was more frequent with longer SE duration (37 vs. 23 h, p = 0.004); furthermore, patients with a toxic-metabolic etiology developed epilepsy less frequently (33% vs. 67%; p = 0.022). Epilepsy was also correlated (tendency) with focal SE (p = 0.073), a lesion in neuroimaging (p = 0.091), and the use of 2 or more AEDs (p = 0.098). Regarding SE duration, a cutoff of above 24h was clearly related to chronic seizures (p = 0.014); however, combining etiology and duration, the association of longer SE and epilepsy was significant in acute lesional SE (p = 0.034), but not in epilepsy with cryptogenic or remote/progressive etiology. After a logistic regression, only a duration longer than 24h (OR = 3.800 (1.277-11.312), p = 0.016) was found to be an independent predictor of the development of epilepsy.

In patients with SE, the longer duration is associated with an increased risk of subsequent epilepsy at follow-up, mainly in symptomatic SE due to an acute lesion. It is unclear if it might be the result of a more severe injury causing both prolonged seizures and subsequent epilepsy, and therefore whether more aggressive treatment in this group might avoid this possibility. Most of the patients with cryptogenic or remote/progressive SE developed epilepsy regardless of SE duration. This article is part of a Special Issue entitled "Status Epilepticus".