Abstracts

A patient[apos]s outcome after epilepsy surgery is usually apparent by one year. Those who have been seizure-free since surgery usually remain so unless they attempt to stop all of their antiepileptic medication. About half of those who stop their medications do so successfully and remain seizure free. However, there is a very small group of patients who are seizure free, off or on medication, who have recurrent seizures many years after their surgery. This study was undertaken to see if there were any common characteristics to this small group of patients. Various data bases at the University of Washington were queried to identify patients who had been seizure free for at least five years after surgery. We then identified any patients in that group for whom there were data indicating they had had a recurrence of their seizures. Actual clinical records were then reviewed to confirm long-term seizure freedom and recurrence and data were abstracted from those records. Nine patients were seizure free for at least 9 years after surgery and then relapsed. One additional patient relapsed in the 6th year year after surgery. An 11th patient developed simple partial seizures after stopping medications after year 4 and had complex partial seizures starting in year 10. Age at onset ranged from 2 months to 19 years and surgery occurred 5 to 29 years later. Seizures recurred as late as 38 years after surgery in one patient and and 22, and 23 years later in two others. Although 58% of all of our resections are left-sided, only 37% of this group had left sided operations. Two of those had right -sided language so that 82% of this group were operated on in the non-language dominant hemisphere. In a comparable group of 12 patients who remained seizure free only 42% had non-dominasntr resections.
All of these patients had temporal resections as part or all of their surgery. However, atypical for our temporal resection patients as a whole, 9 of the 11 did not have hippocampal resections. Long term 9 of 11 of these patients have continued to have seizures at last follow-up. Two have had a second surgery and one of those still has frequent seizures. In this small group of patients with late recurrence of seizures after apparent successful surgery two findings stand out. First, this group has an excess proportion, compared to our population as a whole, of non-dominant hemisphere resections. Second, this group had only 2 patients in whom hippocampal resections were undertaken whereas the majority of our temporal operations include hippoxcampal resection. This finding is consistent with other evidence that extent of hippocampal resection correlates with outcome. These patients may have remained seizure free if their original surgeries had been more complete.