Abstracts

Rationale: Prodromes are reported in up to 29% of patients with epilepsy, occurring between 30 minutes and 1 day prior to a seizure. There has been debate about where these symptoms lie on the ictal interictal continuum. We report 2 patients, one with focal epilepsy and one with generalized epilepsy, each with prolonged prodromes and associated EEG changes while in the Epilepsy Monitoring Unit (EMU). Methods: Two patients were identified that recently were evaluated in the EMU, one with generalized epilepsy, one with focal epilepsy. Subjective review was performed for both cases at the time of the EMU admission. Quantitative analysis was performed on the patient with focal epilepsy. Results: A 44 year-old right-handed male with intractable epilepsy was in the EMU for seizure localization. On the third day of admission, he reported his typical prodrome, consisting of feeling funny , agitation and slow speech. Later that day, he had 2 secondarily generalized tonic-clonic seizures arising from the mesial left frontal lobe. His baseline EEG showed a posterior dominant rhythm of 9 Hz. The EEG prior to his seizures showed increased power in the 8 Hz band, which was widely distributed, monomorphic, and did not attenuate with eye opening. Quantitative EEG showed increased rhythmicity and coherence between the left and right posterior regions in the same band. These changes abated after his second seizure and a dose of intravenous lorazepam. A 43 year-old right-handed woman with primary generalized epilepsy was admitted to the EMU for spell classification for events of crying and increased emotionality. She lived at home alone and the correlation of these events to her habitual seizures was unclear. In the EMU, she had a three hour period of crying and slowed responsiveness. She subsequently had a generalized clonic- tonic- clonic seizure, which was generalized in onset. In the period prior to the seizure, there was significantly increased activation of generalized atypical spike and polyspike and wave discharges. After she had 2 seizures, she again became emotional with altered responsiveness, with increased generalized activation. She was given lorazepam, with subsequent clinical and EEG improvement. Conclusions: Prodromes are relatively common in patients with focal and generalized epilepsy. In our patient with focal epilepsy, quantitative analysis showed increased power, rhythmicity and bilateral coherence, at a frequency lower than his baseline posterior rhythm. In our patient with generalized epilepsy, the EEG changes associated with the prodrome were definitively epileptiform and readily evident on review of the EEG. The cases demonstrate that prodromes have associated electrophysiological changes that can be identified on scalp EEG. These cases demonstrate symptoms patients experience exist on an ictal- interictal continuum, rather than a dichotomy.