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Fitzgerald Z, Morita-Sherman M, Hogue O, Joseph B, Alvim MKM, Yasuda CL, Vegh D, Nair D, Burgess R, Bingaman W, Najm I, Kattan MW, Blumcke I, Worrell G, Brinkmann BH, Cendes F, Jehi L. Improving the prediction of epilepsy surgery outcomes using basic scalp EEG findings. Epilepsia 2021; 62:2439-2450. [PMID: 34338324 PMCID: PMC8488002 DOI: 10.1111/epi.17024] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 06/15/2021] [Accepted: 07/15/2021] [Indexed: 12/23/2022]
Abstract
OBJECTIVE This study aims to evaluate the role of scalp electroencephalography (EEG; ictal and interictal patterns) in predicting resective epilepsy surgery outcomes. We use the data to further develop a nomogram to predict seizure freedom. METHODS We retrospectively reviewed the scalp EEG findings and clinical data of patients who underwent surgical resection at three epilepsy centers. Using both EEG and clinical variables categorized into 13 isolated candidate predictors and 6 interaction terms, we built a multivariable Cox proportional hazards model to predict seizure freedom 2 years after surgery. Harrell's step-down procedure was used to sequentially eliminate the least-informative variables from the model until the change in the concordance index (c-index) with variable removal was less than 0.01. We created a separate model using only clinical variables. Discrimination of the two models was compared to evaluate the role of scalp EEG in seizure-freedom prediction. RESULTS Four hundred seventy patient records were analyzed. Following internal validation, the full Clinical + EEG model achieved an optimism-corrected c-index of 0.65, whereas the c-index of the model without EEG data was 0.59. The presence of focal to bilateral tonic-clonic seizures (FBTCS), high preoperative seizure frequency, absence of hippocampal sclerosis, and presence of nonlocalizable seizures predicted worse outcome. The presence of FBTCS had the largest impact for predicting outcome. The analysis of the models' interactions showed that in patients with unilateral interictal epileptiform discharges (IEDs), temporal lobe surgery cases had a better outcome. In cases with bilateral IEDs, abnormal magnetic resonance imaging (MRI) predicted worse outcomes, and in cases without IEDs, patients with extratemporal epilepsy and abnormal MRI had better outcomes. SIGNIFICANCE This study highlights the value of scalp EEG, particularly the significance of IEDs, in predicting surgical outcome. The nomogram delivers an individualized prediction of postoperative outcome, and provides a unique assessment of the relationship between the outcome and preoperative findings.
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Affiliation(s)
| | | | - Olivia Hogue
- Quantitative Health Sciences, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Boney Joseph
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
| | | | | | - Deborah Vegh
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Dileep Nair
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Richard Burgess
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - William Bingaman
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Imad Najm
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Michael W. Kattan
- Quantitative Health Sciences, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Ingmar Blumcke
- Institute of Neuropathology, University Hospitals Erlangen, Erlangen, Germany
| | - Gregory Worrell
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Fernando Cendes
- Department of Neurology, University of Campinas, Campinas, Brazil
| | - Lara Jehi
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, Ohio, USA
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