Abstracts

Rationale: Generalized interictal epileptiform discharges caused by secondary bilateral synchrony from a mesial frontal epileptogenic focus is thought to require an intact corpus callosum. We describe a case of a patient with partial agenesis of the corpus callosum presenting with interictal generalized epileptiform discharges on EEG in the setting of myoclonic seizures. Interictal EEG demonstrated an abundance of generalized discharges, in addition to a population of right frontocentral focal discharges. We suspect the generalized discharges are due to secondary bilateral synchrony arising from a right frontocentral focus. Our intent is to study the callosal tracts that are anatomically necessary to generate such secondary bilateral synchrony. Methods: We will describe the clinical and electrographic features of our incident case. Using imaging data from high-resolution magnetic resonance imaging and diffusion tensor imaging, we will display the white matter tracts within the corpus callosum that were anatomically intact, and in this case, were required to generate secondary bilateral synchrony. We will review the literature on interictal EEG abnormalities in patients with partial agenesis of the corpus callosum, and the mechanisms behind secondary bilateral synchrony Results: A 27-year woman with a history of partial agenesis of the corpus callosum, arthrogryposis, hypopituitarism, and development delay in childhood, presented with a new onset of intermittent isolated random jerks affecting her arms and legs.  Routine EEG demonstrated frequent generalized spikes and polyspikes, maximum in frontocentral regions bilaterally.  In addition, a population of focal spikes and polyspikes were recorded from the right frontocentral region.  No additional focal spike populations were seen.  Previous MRI reports were noted to demonstrate partial agenesis of the corpus callosum associated with an interhemispheric cyst.  A high-resolution MRI and DTI will be obtained for further analysis. Conclusions: Epilepsies are reported in up to two-thirds of patients with complete or partial agenesis of the corpus callosum, but often an associated malformation of cortical development is causal.  The interictal EEG in epileptic patients with corpus callosum agenesis will typically demonstrate interhemispheric asynchrony or multifocal discharges due to disrupted interhemispheric connections.  Based on our findings, we conclude that an intact corpus callosum is not required to generate secondary bilateral synchrony in the form of generalized interictal epileptiform discharges.  Using MRI and DTI imaging data we will demonstrate a case of partial agenesis of the corpus callosum associated with this electrophysiological phenomenon.  Furthermore, focal-onset myoclonic seizures caused by secondary bilateral synchrony has been reported in the literature and we suspect this rare clinical manifestation applies to our patient. Funding: No funding received.