Semiology of Seizures Involving the OFC: A Narrative Review About a Silent Epilepsy

Summary: The orbitofrontal cortex (OFC) is a highly interconnected region, cytoarchitectonically diverse. Seizures involving the OFC present significant diagnostic challenges because of their variable semiological features, which often overlap with those typically attributed to frontal and temporal epilepsies. Moreover, OFC seizures semiology is shaped by the epileptogenic zone network (EZN), involving either ictal propagation or reconfiguration of functional networks. We systematically reviewed 87 patients presenting seizures involving the OFC to analyze semiological profiles using the latest International League Against Epilepsy classification. We found that seizures with EZN restricted to the OFC displayed sparse semiology, including hyperkinetic behaviors, verbal automatisms, and frequent sleep association, while extended EZN seizures exhibited richer semiological profiles, varying according to EZN distribution. Temporal involvement correlated with more auras, oro-alimentary automatisms, and occurred more often with sleep, while frontal and insular participation involved hyperkinetic behaviors with more mimic and gestural automatisms. Semiological profiles of the OFC-restricted EZN seizures are concordant with propagation patterns that align with the functional connectivity of the OFC: lateral OFC seizures tend to propagate to the lateral and mesial frontal lobe while medial OFC seizures propagated to temporal lobe, either medial or polar. Despite population-level observations, semiological profiles alone seem insufficient for delimitation of extension or distribution of EZN. According to seizure semiology, “frontal” like profiles appear more frequent (∼2/3 of patients) while “temporal” like profiles were more associated with an extended EZN. These findings underscore the importance of comprehensive presurgical evaluations, to delineate EZN extension and distribution in seizures involving the OFC.