Cyclic Recurrence of Seizures as a Marker for Super-Refractory Status Epilepticus

Continuous EEG (cEEG) monitoring during status epilepticus (SE) has enabled the identification of cyclic seizures, characterized by recurrent seizures at regular intervals. However, their clinical implications and prognostic significance remain underexplored. This study aimed to compare patients with cyclic seizures [CSp] and those with noncyclic, sporadic seizures (noncyclic seizures patients [NCSp]) during SE, focusing on clinical features, EEG dynamics, and their impact on survival and functional outcomes.

In this retrospective study conducted in a tertiary neuro-ICU, we identified patients who developed cyclic seizures during SE and compared them with patients exhibiting sporadic seizures without a cyclic pattern. All patients underwent continuous-EEG monitoring for at least 24 h.

Among 138 patients with SE, 12% exhibited CSp, characterized by the absence of clinical correlates, focal onset, and short duration. Seizures recurred every 5-10 min, either early in SE or following controlled epileptic activity. Acute etiologies were more common in CSp than in NCSp (68.8% vs. 6.7%) with autoimmune encephalitis as the predominant cause. CSp patients were younger (31 vs. 52 years) and had no comorbidities but experienced more severe SE. They had super-refractory SE, required twice as long a stay in the ICU, and had a markedly higher seizure burden (mean of 454 vs. 20 seizures per patient), over the entire monitoring period. The mortality rate reached 30%, and CSp were more likely to develop pharmacoresistant epilepsy, leading to poorer functional outcomes.

Cyclic seizures may represent a critical progression in the evolution of super-refractory SE, linked to higher seizure burden, increased severity, and worse prognosis. Early detection through cEEG might guide timely therapeutic interventions that could improve patient outcomes in this severe condition.