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

Abstract

Objective. The Epilepsy Surgery Grading Scale (ESGS) is a simple method to predict the likelihood of a patient with epilepsy proceeding to surgery and achieving seizure freedom. Usefulness of the ESGS has been confirmed in established epilepsy centres in the United States and Belgium for adult patients with drug-resistant focal epilepsy undergoing presurgical evaluation. However, the applicability of the ESGS has not yet been evaluated in a wider range of epilepsy patients that may reflect the general spectrum of epilepsy. The present study validated the ESGS in a Japanese epilepsy centre in which admission-based comprehensive epilepsy studies were indicated beyond presurgical evaluation. Methods. This single-centre retrospective study included adult patients with epilepsy admitted to the Epilepsy Monitoring Unit from 2010 to June 2019. Patients were classified as ESGS Grade 1 (most favorable), Grade 2 (intermediate), and Grade 3 (least favourable). Patients were grouped into three cohorts: all patients, patients with drug-resistant focal epilepsy, and patients who underwent resective epilepsy surgery. We assessed progression to surgery and seizure freedom at one year after surgery. Results. Of the 1,158 total admissions, 670 patients met the inclusion criteria and formed the total cohort. Of these, 435 (64.9%) had drug-resistant focal epilepsy and 78 (11.6%) proceeded to resective surgery. Overall, progression to surgery was observed in 41.3%, 16.6%, and 4.8% of patients with Grade 1, 2, and 3, respectively. In the surgical cohort, seizure freedom was observed in 85.2%, 65.2%, and 31.3% of patients with Grade 1, 2, and 3, respectively. Significance. Our results indicate that the ESGS is effective in predicting whether a patient proceeds to epilepsy surgery and achieves seizure freedom even in the general population of epilepsy patients, regardless of type or resistance to antiepileptic drugs.

Prediction tools and risk stratification in epilepsy surgery

“…The Epilepsy Surgery Grading Scale (ESGS) was developed to predict the likelihood of the patient both of progressing to surgery, and of becoming free of disabling seizures, classifying the patients into three distinct groups: most favorable, intermediate, and least favorable 7 . ESGS was validated on two independent cohorts, which confirmed the usefulness of this tool 8,9 . The Seizure Freedom Score (SFS) and the modified Seizure Freedom Score (m‐SFS) were developed in a similar fashion to predict seizure freedom after resective epilepsy surgery 10 .…”

“…Patients missing critical clinical variables or outcome were excluded from the analyses. We analyzed the data using the two scales (ESGS and SFS) [8][9][10] and two versions of ESN (the original 11 and modified versions 12 ). m-SFS was not used in this study due to a high proportion of missing data required for that tool.…”

“…7 ESGS was validated on two independent cohorts, which confirmed the usefulness of this tool. 8,9 The Seizure Freedom Score (SFS) and the modified Seizure Freedom Score (m-SFS) were developed in a similar fashion to predict seizure freedom after resective epilepsy surgery. 10 SFS and m-SFS have not yet been validated externally.…”