Neurophysiological seizure-onset predictors of epilepsy surgery outcome: a multivariable analysis
OBJECTIVE
The authors sought to determine which neurophysiological seizure-onset features seen during scalp electroencephalography (EEG) and intracerebral EEG (iEEG) monitoring are predictors of postoperative outcome in a large series of patients with drug-resistant focal epilepsy who underwent resective surgery.
METHODS
The authors retrospectively analyzed the records of 75 consecutive patients with focal epilepsy, who first underwent scalp EEG and then iEEG (stereo-EEG) for presurgical assessment and who went on to undergo resective surgery between 2004 and 2015. To determine the independent prognostic factors from the neurophysiological scalp EEG and iEEG seizure-onset information, univariate and standard multivariable logistic regression analyses were used. Since scalp EEG and iEEG data were recorded at different times, the authors matched scalp seizures with intracerebral seizures for each patient using strict criteria.
RESULTS
A total of 3057 seizures were assessed. Forty-eight percent (36/75) of patients had a favorable outcome (Engel class I–II) after a minimum follow-up of at least 1 year. According to univariate analysis, a localized scalp EEG seizure onset (p < 0.001), a multilobar intracerebral seizure-onset zone (SOZ) (p < 0.001), and an extended SOZ (p = 0.001) were significantly associated with surgical outcome. According to multivariable analysis, the following two independent factors were found: 1) the ability of scalp EEG to localize the seizure onset was a predictor of a favorable postoperative outcome (OR 6.073, 95% CI 2.011–18.339, p = 0.001), and 2) a multilobar SOZ was a predictor of an unfavorable outcome (OR 0.076, 95% CI 0.009–0.663, p = 0.020).
CONCLUSIONS
The study findings show that localization at scalp seizure onset and a multilobar SOZ were strong predictors of surgical outcome. These predictors can help to select the better candidates for resective surgery.
ABBREVIATIONS
EEG = electroencephalography; iEEG = intracerebral EEG; SOZ = seizure-onset zone; TLE = temporal lobe epilepsy.The Neurosurgery Research & Education Foundation (NREF) is celebrating its 40th anniversary this month. Since its inception, the NREF has invested nearly $30 million in the future of neurosurgery through its support of basic science and clinical research, as well as life-long education, to foster improved outcomes for our patients with neurosurgical diseases. See the article by Agarwal et al. (pp 1905–1912).
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