Caught on Tape: How Video Clarified Focal to Bilateral Tonic-Clonic Seizures?

The Secondarily Generalized Tonic-Clonic Seizure: A Videotape Analysis Theodore WH, Porter RJ, Albert P, Kelley K, Bromfield E, Devinsky O, Sato S. Neurology. 1994 Aug;44(8):1403-1407. doi: 10.1212/wnl.44.8.1403. PMID: 8058138. We studied 120 generalized tonic-clonic seizures (GTCSs) in 47 patients with video-EEG telemetry. GTCSs were preceded by antecedent seizures, including 13 simple partial, 70 complex partial, 17 simple partial leading to complex partial, 7 tonic, 7 clonic, and 1 typical absence. We divided GTCSs into the following phases: onset of generalization, pretonic clonic, tonic, tremulousness, and clonic. The mean GTCS duration was 62 s. There was a nonsignificant trend toward longer duration on reduced antiepileptic drug doses. Marked heterogeneity in GTCS phenomenology was present; only 27% of seizures included all 5 phases. Individual phase duration and clinical expression, including tonic and clonic phases, was highly variable. The clinical phenomena suggest that multiple cortical and subcortical routes of spread may exist. When GTCSs last longer than 2 min, intravenous antiepileptic drug treatment should be initiated.