Faculty Bibliography

Seizure and epilepsy are common neurologic issues in cancer patients. Etiologies include structural abnormalities of the brain (eg, brain metastasis), cerebrovascular disease, reversible posterior leukoencephalopathy syndrome (RPLS), and radiation toxicity. Seizures associated with these etiologies often have focal features. Metabolic causes include hypoglycemia, electrolyte abnormalities, tumor lysis syndrome, thrombotic thrombocytopenic purpura (TTP), and medications used in cancer. A careful clinical evaluation can suggest the seizure etiology and guide subsequent work-up. Nonconvulsive status epilepticus should be suspected with persistent decreased level of consciousness following a seizure. Certain etiologies, such as RPLS and TTP, must be treated aggressively to minimize permanent neurologic injury. Routine prophylaxis with antiepileptic drugs (AEDs) is not recommended in patients with primary brain tumors or brain metastasis who have never had a seizure. Where indicated, the selection of AEDs should take into consideration side effects and interactions with chemotherapy. For this reason, non-enzyme-inducing AEDs are preferable in the cancer setting.

Determining the status of breast cancer surface receptors (estrogen receptor, progesterone receptor, HER2/neu) has become routine in the care of patients with this disease and has proven to be helpful in guiding treatment. For this reason, breast cancer has become a model for molecularly guided therapy in solid tumors. Emerging data support that these receptors are associated with risk for developing brain metastases. Additionally, once brain metastases have occurred these receptors may also correlate with prognosis.

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.