The Epilepsy Surgery Grading Scale: Validation in an independent population with drug‐resistant focal epilepsy

Abstract

The Epilepsy Surgery Grading Scale (ESGS) is a simple tool that predicts a patient's likelihood of progressing to resective surgery and becoming seizure‐free. The aim of our study was to validate the ESGS in an independent patient cohort. We retrospectively calculated the ESGS score for adult patients with drug‐resistant focal epilepsy undergoing presurgical evaluation at two reference centers for drug‐resistant epilepsy in Belgium. We classified patients into ESGS grade 1 (most favorable), grade 2 (intermediate), and grade 3 (least favorable). We assessed progression to surgery and postsurgical seizure freedom. A total of 238 patients underwent presurgical evaluation (presurgical cohort), of whom 140 progressed to surgery (surgical cohort). In the presurgical cohort, we observed significant differences in rates of surgery and in rates of seizure freedom between grades 1, 2, and 3. In the surgical cohort, we observed significant differences in rates of seizure freedom between grades 1 and 2 and between grades 1 and 3. We confirm the usefulness of the ESGS for the prognostic stratification of patients with drug‐resistant focal epilepsy undergoing presurgical evaluation. Our results support the use of the ESGS in the decision process of presurgical evaluation in clinical practice.

External validation of the Epilepsy Surgery Grading Scale in a Japanese cohort of patients with epilepsy

“…In addition, the rates of seizure freedom in our study and the preliminary study [8] are very similar to those of the validation study [9]. Based on examination of the individual parameters, MRI, EEG, and concordance between the two, higher ESGS scores were also more frequent in the surgical cohort, except for MRI findings (table 1).…”

“…The present findings support the potential of the ESGS in predicting the likelihood of seizure‐free status after surgery in patients with epilepsy. The present cohort had different characteristics from the two previous studies [8, 9], but our results confirm applicability of the ESGS to geographically independent populations of patients with epilepsy. The present study, in which the participants reflected those in a general neurology clinic setting, emphasizes that the ESGS has the potential to be adapted worldwide.…”

“…Initial validation of the scale in 407 patients in New York showed that the ESGS effectively stratified patients into these three clinical categories and so could predict the likelihood of seizure freedom after surgery. However, only one validation study has been performed in an independent population with drug-resistant focal epilepsy in Belgium [9]. Results from this study confirm the usefulness of the ESGS in predicting surgical outcomes.…”

Focal epilepsies: Update on diagnosis and classification

“…Therefore, it is in the best interest of patients and health systems to determine best candidates for early epilepsy surgery before they accumulate the negative medical and social outcomes associated with intractability. Patients with unilateral temporal lobe discharges on EEG and a concordant MRI lesion have some of the best changes for postoperative seizure freedom and would benefit most from early surgical referrals 76,77 …”

“…Patients with unilateral temporal lobe discharges on EEG and a concordant MRI lesion have some of the best changes for postoperative seizure freedom and would benefit most from early surgical referrals. 76,77 Another proposed role for EEG in the management of patients with focal epilepsy is to identify patients who can be withdrawn from antiseizure medication(s) after prolonged seizure freedom. There is some controversy as to whether an abnormal EEG, including epileptiform discharges, indicates risk of relapse in weaning antiseizure medication(s).…”