Abstracts

CNS neoplasms are frequently the cause of new adult onset seizures. Treatment involves treatment of the neoplasm as well as adjuvant antiepileptic drug therapy (AED). Phenytoin has historically been used as the AED of choice. As a P450 3A4 metabolized AED, it may alter chemotherapy drug (CD) efficacy. Efficacy of new AEDs and CD efficacy needs to be evaluated in treatment of patients with CNS neoplasms. Retrospective review of patients referred for brain mapping or new onset seizures due to tumors from Jan 1999 to April 2004 was performed noting: tumor type, location, presenting symptoms, presence of seizures at onset, result of AED treatment, tumor treatment and functional status at last visit. Forty patients ages 18-77 were reviewed (26 males, 15 females). Tumors were: 5 glioblastomas, 10 astrocytomas, 7 oligoastrocytoma, 10 oligodendrogliomas, 1 meningioma, 1 ganglioglioma, 2 DNET, 5 unknown. All received AEDs; 81.6% had resection; 45% had CD; 55% had radiation; 10% cyberknife therapy. AEDs used: gabapentin (GBP) monotherapy (MT) 3; levetiracetam (LEV) MT 22 and polytherapy (PT) 5; oxcarbazepine (OXC) 3 MT and 3 PT; phenytoin MT 2 and 1 PT; topiramate (TPM) MT 1. CD utilized were temozolomide 72.2%; BCNU/CCNU 10%; and 5% each cisplatin, procarbazine, thalidomide, etoposide and imatinib. There were 5 deaths (12.5%) and 7 lost to follow-up. 87.5% presented with seizures. 77.8% of LEV patients were seizure free or only SPS. 71.4% OXC were seizure free or SPS only. The 1 TPM patient was seizure free. No phenytoin patients were seizure free. Tumor treatment resulted in survival and good functional outcome in 84.8%. AEDs with no or minimal hepatic metabolism include GBP, LEV, TPM. OXC is reduced by a noninducible ketoreductase. CD metabolic pathways vary: temozolomide is conjugated; etoposide, BCNU and CCNU are hydroxylated; procarbazine, imatinib and vincristine are oxidized and inducible. Dexamethasone, frequently utilized initially, induces P450 AED metabolism. Choice of CD regimen is not often know at time of initial diagnosis. Choice of GBP, LEV, OXC or TPM would potentially avoid drug interactions and allow maximum CD effectiveness. All 4 AEDs showed excellent seizure outcome whereas phenytoin did not, although numbers are small. Patients with CNS neoplasms should be given maximum opportunity for successful outcome both for seizure control and survival. Treatment of seizures in these patients is effective utilizing GBP, LEV, OXC, and TPM with low risk of interfering with chemotherapy.