Abstracts

The focus localization ability of interictal activity have been discussed. With the increasing possibilities with imaging methods, interictal activity and MRI findings have been suggested as sufficient for focus localization. This presentation gives the relation between ictal and interictal activity as recorded in the database at The National Centre for Epilepsy in Norway.
Every long time monitoring (LTM) have since 1992 had their results coded in a database. A record holds 2 interictal and 2 ictal entries with lobe, side and type of activity. Five years of recordings, 1995-2000, from the database holds a total of 4500 records. Of these 1149 where complete and contained seizures.
A total of 611 LTMs showed both interictal and ictal activity of which 457 were focal. Fiftythree percent of the patients had a temporal focus. Of the patients having a left focal interictal finding, 8.3% showed a clear right sided focal ictal finding, while 11.5% of the right sided interictal activity showed a clear focal left ictal finding.
These finding suggest that some 10% of cases with focal interictal findings will have clear ictal findings on the opposite side. These findings are not compared to other methods as MRI. It is unclear if the interictal or ictal activity gives the best results, but combination of interictal and ictal activity gives more useful information.