Recurrent secondary generalization in frontal lobe epilepsy: Predictors and a potential link to surgical outcome?

Abstract

SUMMARYObjective: Frontal lobe epilepsy (FLE) frequently leads to secondary generalized tonic-clonic seizures (SGTCS). However, little is known about the clinical, electrophysiologic, and radiologic correlates of SGTCS and whether these could influence diagnosis and treatment. Methods: A cohort of 48 patients with confirmed FLE was retrospectively identified and dichotomized into a group with and a group without SGTCS defined by history (≥1/year) or video-electroencephalography (vEEG). Demographics, seizure semiology, vEEG, neuroimaging data, and estimated seizure-onset zone were tabulated, and their association with the occurrence of SGTCS was evaluated with use of a chi-square test. Independent predictors of SGTCS were confirmed using a stepwise multivariate analysis. Similarly, these predictors as well as a history of SGTCS were tested as multivariate predictors of the postoperative International League Against Epilepsy (ILAE) score in the surgical subgroup (n = 25). Results: We identified three independent predictors of a history of SGTCS in FLE, including loss of responsiveness at seizure onset (corrected p = 0.04), a semiology involving early elementary motor signs (corrected p = 0.01), and multifocal spikes on EEG (corrected p = 0.02). A seizure-free outcome occurred in 57% of surgical cases and was more likely in the group without SGTCS (100%, p = 0.001). When considering only SGTCS occurring during video-EEG monitoring, the association with semiology and surgical outcome vanished, but the association with preserved awareness and a multifocal EEG persisted. Significance: A history of SGTCS is related to a specific ictal semiology and interictal EEG, and may have a role in surgical risk stratification.

Seizure pathways change on circadian and slower timescales in individual patients with focal epilepsy

“…Contrary to the expectation that high levels of seizure variability may worsen surgical outcomes, we found no association between these patient features. It may be that only some types of variability, such as multifocal (9) or secondarily generalized (73) seizures, impact the likelihood of seizure freedom following surgery. Importantly, variability in the seizure onset network state does not indicate that a patient has multifocal seizures, as different network configurations can be associated with the same apparent ictal onset zone.…”

Focal to bilateral tonic–clonic seizures are associated with widespread network abnormality in temporal lobe epilepsy

“… 45 Metrics such as node abnormality, 30 network abnormality, 29 and deviation score 13 , 17 can quantify patient‐specific heterogeneities, thus stratifying patients on a spectrum of disease severity rather than dichotomized groups. Multivariate combinations of clinical factors associated with FBTCS 7 , 11 with our proposed patient‐specific abnormality measure may be able to determine patient susceptibility to FBTCS. Identifying predisposition of patients to FBTCS may be particularly relevant in epilepsy monitoring units, where anti‐seizure drug tapering carries a risk of FBTCS.…”

“…Recognizing the need to quantify patient susceptibility to FBTCS, some studies have investigated a range of clinical factors to differentiate patients with and without FBTCS, 7,11 showing positive association with the presence of hippocampal sclerosis and negative association with ictal speech and pedal automatism 7 . Many studies have suggested that impairments in specific brain regions support FBTCS, after finding disrupted structure and function in circuits mediated by thalamus and basal ganglia 6,12–18 .…”

Generalized seizures presurgically in a cohort of children with hemispherectomy: Predictors and a potential link to surgical outcome?

“…Kaplan-Meier survival analysis was performed to calculate the probability of seizure-free rate after surgery. Significance at P < 0.05 was statistically significant, and P-values >5% but <10% were reported to reflect trends [15]. All statistical analyses were performed using SPSS 20.0.…”