Abstract
As early in 1935, Gibbs et al described electroencephalogram (EEG) features of large
slow waves seen in “petit mal” seizures and change in background rhythm to a higher
frequency, greater amplitude pattern in “grand mal” seizures. Studies have shown many
typical EEG features in focal onset as well as generalized epilepsies.[2]
[3] It is usually easy to delineate focal epilepsy cases when EEG onset of seizures
is clear as seen in Benign focal epileptiform discharges of childhood.[4] However, it is not uncommon to see cases where epileptiform discharges are not very
clear. For example, there can be secondary bilateral synchrony or generalized onset
of epileptiform discharges in some cases of focal epilepsy[5] and nongeneralized EEG features is cases of generalized epilepsy like absence seizures.[6]
The awareness of occurrence of focal clinical and EEG features in generalized epilepsy
is particularly important to help to select appropriate AEDs and also to avoid inappropriate
consideration for epilepsy surgery.[7] Lüders et al[8] have shown that multiple factors like electroclinical seizure evolution, neuroimaging
(both functional and anatomical) have to be analyzed in depth before defining an epileptic
syndrome. Here, we are providing few examples of different situations where it is
still mysterious to figure out focal onset seizures with secondary generalization
versus primary generalized epilepsy.
Keywords
electroencephalogram - focal epileptiform discharges - generalized epileptiform discharges
- secondary bilateral synchrony
