Abstract
Objective
To determine duration of epileptic seizure types in patients who did not undergo withdrawal of antiseizure medication.
Methods
From a large, structured database of 11,919 consecutive, routine video-electroencephalograpy (EEG) recordings, labelled using the SCORE (Standardised Computer-Based Organised Reporting of EEG) system, we extracted and analysed 2,742 seizures. For each seizure type we determined median duration and range after removal of outliers (2.5-97.5 percentile). We used surface electromyography (EMG) for accurate measurement of short motor seizures.
Results
Myoclonic seizures last <150 ms, epileptic spasms 0.4-2 s, tonic seizures 1,5-36 s, atonic seizures 0,1-12,5 s, when measured using surface EMG. Generalized clonic seizures last 1-24 s. Typical absence seizures are rarely over 30 s (2.75-26.5 s) and atypical absences last 2-100 s. In our patients, duration of focal aware (median: 27 s; 1.25-166 s) and impaired awareness seizures (median: 42.5 s; 9.5-271 s) was shorter than previously reported in patients undergoing withdrawal of antiseizure medication. All focal seizures terminated within ten minutes. Median duration of generalized tonic-clonic seizures was 79.5 s (57-102 s) and of focal-to-bilateral tonic-clonic seizures was 103.5 (77.5-237 s). All tonic-clonic seizures terminated within five minutes.
Significance
This comprehensive list of seizure durations provides important information for characterising seizures and diagnosing patients with epilepsy. The upper limits of seizure durations are helpful in early recognition of imminent status epilepticus.
DIC