Abstracts

Epilepsy surgery in patients with medically refractory multilobar epilepsy is one of the most difficult clinical situation and fraught with many difficult decisions. We retrospectively studied patients with proven multilobar epilepsy with chronic subdural EEG recording. Seizure onset was identified by earliest sustained rhythmic change on EEG that is clearly distinguished from background EEG occurring in association with a clinical seizure. Intraoperative photographs and 3D reconstruction MRI images co-registered with subdural grids were used to identify the location of the seizure onset electrodes. The location of seizure onset zones were divided as follows: inf/medial temporal (MT), temporal neocortex (LT), lateral parietal lobe (LP), medial parietal lobe (MP), lateral frontal lobe (LF), medial frontal (MF), orbito-frontal (OF), lateral occipital lobe (LO), medial occipital (MO), inferior occipital lobe (LO). Frequency of various anatomical regions involved in seizure onset was analyzed. Outcome data was analyzed. We studied a total of 20 children (age 0.7-18 years, 14M, 6F). In patients with multilobar epilepsy, frequency of lobar involvement was as follows: temporal lobe (16/20), parietal lobe (15/20), frontal lobe (9/20) and occipital lobe (1/20). Eighteen patients had 2 lobes involved in seizure onset, while the other 2 had three lobes involvement. Most likely combination in decreasing frequency was as follows: LT-LP (6), LF-LP (4), MT-LF (3), MT-MP (2), and all other combination occurred in a single patient (LT-LF, LT-LO, MT-LP, LF-LP-MP-MT, LF-LP-MF). There are some interesting observations, seizure onset from temporal neocortex are more likely to associate with seizure onset from LP, while MT seizures more likely to combine with LF seizure onset. In most patients with seizure onset involving LF-LP, peri-rolandic region was involved.
The underlying pathology was as follows: Tuberous sclerosis 9, gliosis 6, Neuronal migrational abnormalities 4, and focal polymicrogyria with glial cytoplasmic inclusion 1. The follow-up period since surgery ranged from a month to 2.6 years (mean 1.37 years). The outcome measured per Engle classification for patients who was at least one year from surgery (13 patients): Class I :10 and Class III: 3. Multilobar epilepsy usually occur in patients with widespread abnormalities of cerebral/ neuronal development. Certain brain regions are more likely to be involved in tandem (LT-LP, MT-LF, LF-LP, MT-MP). This fact should be considered while planning subdural grid placement. Epilepsy surgery may provide effective treatment in selected patients with multilobar epilepsy. (Supported by NINDS grant RO1 NS045207-01)