Seizures and anti-epileptic drugs in neuro-oncology

Abstract

Seizures are common in patients with central nervous system cancer, although the exact frequency of seizures depends considerably on the location, growth rate, and histology of the tumor. The occurrence of a first seizure in an adult mandates a neuroimaging study of the brain, preferably an enhanced MRI scan with FLAIR sequences. Focal seizures in children, particularly in the presence of post-ictal or intra-ictal deficits, may also merit a similar evaluation. In patients with known cancer, an MRI scan with FLAIR images and contrast enhancement is the optimum neuroimaging test. Extensive studies to evaluate infectious, metabolic, and drug-related etiologies are also critical, and in many cases a cerebrospinal fluid examination is indicated. While surgical therapy of tumorassociated seizures holds promise, particularly for patients with low-grade primary brain tumors, intraoperative electrocorticography may be required for optimum seizure control, and post-operative anticonvulsant medication is usually necessary. Anticonvulsant medications are associated with more frequent and often more severe side effects in patients with cancer than in patients with other causes for their seizures. These side effects include important interactions with corticosteroids and chemotherapeutic agents, and should influence the choice of anticonvulsant agents and the monitoring schedule of patients under treatment. Prophylactic anticonvulsants are not effective, and should not be used routinely. © 2008 Humana Press, Totowa, NJ.