Clinical commentary Partial agenesis of the corpus callosum in a patient with juvenile myoclonic epilepsy

We describe a patient who presented at our epilepsy-monitoring unit with myoclonic jerks, and was diagnosed with juvenile myoclonic epilepsy (JME). Imaging of his brain revealed partial agenesis of the corpus callosum (ACC). We discuss the known genetic basis of both JME and ACC, as well as the role of the corpus callosum (CC) in primary generalized epilepsy. Both JME and ACC are associated with gene loci on chromosome 15q14. Structural brain abnormalities other than ACC, such as atrophy of the corpus callosum have been reported in patients with JME. ACC has been associated with seizures, suggesting an anti-epileptogenic role of the corpus callosum. On the other hand, corpus callosotomy is used to treat refractory idiopathic generalized epilepsy, which shows that the corpus callosum may play an epileptogenic role. The occurrence of both these conditions in one patient raises the question of whether they are purely coincidental or if there is a common basis for both. Several issues need to be addressed: the mechanism of seizure generalization in the setting of partial ACC, the possible role of other structures in generalization, and whether the ACC contributes to epileptogenesis as a result of the lack of a normal CC inhibitory effect.