Abstracts

Rationale: Although only a minority of children with epilepsy have an underlying central nervous system neoplasm, seizures are common during and after treatment for a primary brain tumor. Risk factors that predispose patients to develop seizures and which define the subpopulation of patients who will develop medically refractory seizure disorders is poorly defined. The objectives of our study were to describe the incidence of seizures in the population of long-term survivors of pediatric brain tumors and to determine risk factors for poor seizure control. Methods: In a retrospective, cross-sectional study, we reviewed the clinical data for all patients presenting for follow-up evaluation during a 12-month period who were at least two years after initial diagnosis of a central nervous system tumor. Clinical data collected included patient demographics, age at diagnosis, length of follow-up, extent of initial resection, tumor histology, and treatment modalities were obtained. For patients who had experienced seizures at any time from initial presentation to the most recent follow-up visit, timing and frequency of seizures. Statistics were calculated with SPSS using chi-square test. Results: The patient cohort in the long-term survivor clinic included a total of 298 patients (140 females). Average duration of follow up after initial diagnosis was 7.6 years. Initial surgical resection was gross-total in110 patients, and subtotal for 143. 30 patients underwent biopsy alone and 16 had no surgical intervention. Tumor localization included posterior fossa (104; 35%), midline (98; 33%), cortical (85; 28%) and other locations (11; 4%). Most frequent tumor pathologies included low grade gliomas (including glial-neuronal tumors and oligodendroglioma), medulloblastoma and ependymoma. 155 patients received radiotherapy and 128 patients underwent chemotherapy (86 patients received both, 29%). Recurrent tumors were seen in 91 patients (30%). Seizures were experienced in 72 patients (24%). Ongoing seizures at the time of most recent follow-up were present in 42 patients (58% of patients with seizures; 14% of cohort). Risk factors for seizures at any time from presentation to last follow-up included tumor location (cortical), tumor histology (glial or glial-neuronal), tumor recurrence and incomplete resection at time of initial presentation. Cortical location, recurrence of tumor and glial tumor pathology were all risk factors for recurrent, refractory seizures. Age at diagnosis, prior treatment with radiation, chemotherapy or both were not predictors of seizures at any time. Conclusions: Seizures are a frequent comorbidity in pediatric brain tumor survivors and were seen in 24% of patient, with refractory ongoing seizures in 14% of patients at time of last follow-up. Factors predisposing for seizures included tumor pathology, location and extent of resection. Factors that were most predictive of poor seizure control included tumor location and presence of residual tumor. Our results may assist in earlier identification and management of patients at highest risk for seizures.