Abstracts

Rationale: Ictal semiology complements ictal EEG in identifying the likely epileptogenic zone. Ictal turning prone (ITP) with rotation along the longitudinal body axis was described as a medial frontal ictal sign. The aim of our study was to evaluate the localizing value of ITP in a general population of patients undergoing long term video-EEG monitoring Methods: We reviewed our epilepsy monitoring unit database for adult patients with recorded habitual seizures with ITP. All 16 patients identified had continuous video-EEG monitoring using standard scalp electrodes; eight patients also had intracranial EEG monitoring. We only included focal seizures without evolution to bilateral tonic-clonic activity. We reviewed and analyzed all presurgical data, identified the ictal onset zone and surgical outcome at last follow up of all eligible patients. Results: We identified 16 patients with ITP, with an average age of 32.5 years (range 18-50). ITP was consistently seen in at least one focal impaired awareness seizure of all patients. Ictal onset zone on scalp EEG was left temporal in five, right temporal in three, left frontal convexity in two, right frontal convexity in two, probable right medial frontal in three and probable left medial frontal in one patient. Eight patients also had intracranial EEG monitoring. Direction of ITP was uni-directional in 12 patients while 4 patients had ITP in opposite direction in different seizures.Nine patients underwent surgery. Three patients had cingulate resection, one patient had temporal lobectomy, one had orbitofrontal resection, and one patient had right selective amygdalohippocampectomy.  Three patients had a responsive neurostimulator (RNS) implanted, Five patients had Engel class I outcome while four patients had Engel class III outcome. Out of four patients with bidirectional ITP, two underwent resective surgery with subsequent Engel 1A outcome, while the other patient had RNS implanted with an Engel III outcome. Conclusions: Ictal turning prone does not have a consistent single localizing or lateralizing value and can be seen with various epileptogenic zones including medial frontal, lateral frontal or temporal.  In addition, ITP direction can vary even with a single epileptogenic zone. A bidirectional ITP does not indicate bilateral epileptogenic zones and does not exclude epilepsy surgery. Funding: None