Abstracts

Rasmussen[apos]s syndrome is a progressive illness leading to intractable seizures and eventual cognitive decline. Hemispherectomy is the only effective treatment. There is little literature available as to the electrographical pattern seen on electrocorticography (ECoG).
Eight children (ages 3.5 to 14.6 at surgery) with Rasmussen[apos]s syndrome and ECoG studies were reviewed. ECoG patterns were described as single spike, runs of spikes, paroxysmal fast activity (PFA), slowing and attenuation, and spontaneous seizures. [quot]Fast burners[quot] (n=3) were defined as patients who presented with status epilepticus and had seizure onset to time of surgery of less than one year.
The second oldest child underwent a subdural grid recording in addition to 2 ECoGs due to language and motor function and eventually had a tailored parietal resection. The oldest child had a frontal resection due to language dominance. One child underwent a limited parietal resection first in order to preserve motor function, then continued to seize and a hemispherectomy was performed later. The rest of the patients had hemispheretomies (R=3, L=3).
On ECoG, the 2 children younger than age 4 had involvement of the posterior quadrant only while the older children showed abnormalities in the frontal and central regions. Single spikes and runs of spikes were noted in all except for the oldest patient. PFA and multiple seizures were found only in 2 of the [quot]fast burners[quot]. One of these [quot]fast burners[quot] had electrographical seizures during ECoG with multiple seizure onsets that were captured in the parietal and occipital lobes. In 2 patients who had repeated ECoG after resection, abnormalities were seen in areas that were outside the original resection. Of these 2 patients, one underwent a hemispherectomy, and the other could not be resected further due to language and motor function.
At 3 year follow-up, seizures continued in the 2 oldest patients who had only partial resection due to language dominance. One of the [quot]fast burners[quot] who underwent a hemispherectomy continued to seize 6 months later with a scalp EEG showing spikes and PFA from the contralateral hemisphere.
Younger children had involvement of the posterior quadrant while older children showed abnormalities in the frontal and central regions. Patients who are [quot]fast burners[quot] were found to have PFA and multiple seizures on ECoG. Abnormalities on repeat ECoG may be noted in areas that were beyond the resection margin. This may explain why there is likelihood of disease progression without a complete hemispherectomy. One patient had spikes from the contralateral hemisphere on follow-up scalp EEG which suggests that Rasmussen[apos]s may not necessarily affect a single hemisphere.