Yes, an EEG can show no evidence of active seizures, but still show changes in the electrical patterns of the brain that might indicate the possibility of seizures, especially if your DD is having symptoms.
As for post-seizure activity, if the person has had a seizure, then there will be abnormal electrical activity in the brain that may last for a bit, so yes, it is possible to see this abnormal electrical activity after a seizure, but it will depend on if the activity lasts long enough to be caught on EEG. Some people with Epilepsy have completely normal EEGs between seizures, so if you are not "lucky" enough to catch an active seizure, then the EEG won't tell you anything about the seizures.
at 4:09 PM on Jul. 16, 2009