Defining the extent of the epileptogenic zone is particularly problematic in posterior cortex epilepsies (PCEs). Non-invasive information is frequently insufficient for surgical planning, and individually tailored surgery is likely to be curative only when guided by invasive investigation. Stereotactic placement of intracerebral multicontact electrodes is performed according to an individually tailored pre-implantation hypothesis of the presumed epileptogenic zone and, in the posterior cortex, usually follows three main exploration patterns, in relation to the origin and preferential spreading pattern of ictal discharges. This chapter presents the methodology for stereo-EEG (SEEG) exploration of PCEs by means of illustrative cases. It also presents the characteristics and the surgical outcome and its determinants of a cohort of patients operated on for drug-resistant PCE, about half of whom underwent invasive investigation by SEEG. Duration of epilepsy represented the most consistent predictor of surgical outcome, with early surgery being correlated with higher chances of surgical success.
Effect of hypopnoea scoring criteria on non-invasive assessment of loop gain and surgical outcome prediction
