%0 Review
%T Electrographic seizure duration and inter-seizure intervals in focal status epilepticus.
%A Meletti S
%A Turchi G
%A Orlandi N
%A Vaudano AE
%A Cioclu MC
%A Pugnaghi M
%A Giovannini G
%J Epileptic Disord
%V 25
%N 4
%D 2023 Aug 11
%M 37170072
%F 2.333
%R 10.1002/epd2.20071
%X <B>OBJECTIVE: </B>To characterize the duration of seizures and inter-seizure intervals in focal status epilepticus (SE).<BR><B>METHODS: </B>We reviewed consecutive scalp EEG recordings from adult patients who were admitted for a first episode of focal status epilepticus. We identified electrographic seizure duration and inter-seizure intervals in the first diagnostic pretreatment EEG. We also reviewed isolated focal self-limiting seizures in epilepsy patients, as a comparison group for seizure duration.<BR><B>RESULTS: </B>We recorded 307 focal seizures in 100 consecutive focal SE episodes, with a median seizure duration of 107 s (IQR: 54-186), and 134 isolated focal self-limiting seizures in 42 epilepsy patients, with a median duration of 59 s (IQR: 30-90; p < .001). The only clinical feature of SE that significantly increased seizure duration was acute symptomatic etiology. In SE, 15% and 7% of seizures lasted longer than 300 and 600 s, respectively (t1 of the actual definition for tonic-clonic and focal SE), while only 1% of self-limiting seizures lasted longer than 300 s, and none lasted longer than 600 s. The analysis of inter-seizure intervals in SE with multiple seizures showed that 50% of the inter-seizure periods were shorter than 60 s, and 95% were shorter than 540 s (9 min). Patients who had an increase in seizure duration (last versus first) of at least 1.4 times showed an increased 30-day mortality.<BR><B>CONCLUSIONS: </B>Focal seizures within a SE episode showed a wide range of duration, partly overlapping with the duration of focal self-limiting seizures but with a longer median duration. Inter-seizure intervals within an episode of SE were shorter than 1 min in 50% of the seizures and never lasted more than 10 min. Finally, an increase in seizure duration could represent an "electrophysiological biomarker" of a more severe SE episode, which may require more aggressive and rapid treatment.