Activity Seventy-one patients had seizures at any point from before their diagnosis to years after therapy had been completed.1 Although most of the seizure activity took place prior to or at the time of diagnosis (10% of entire cohort, 42% of patients with seizures), there were 12 patients whose seizure activity began during treatment, and 16 patients whose seizures actually occurred more than 2 years after the treatment period was over. There were 43 patients who had ongoing seizures during the time of their latest follow-up visit.1
Most of the seizures were complex partial and generalized, or secondarily generalized seizures. Two of the patients had status epilepticus during the time they took part in the study.
Predictors There are some ways to predict whether a child will have seizure activity. Pediatric seizures are most commonly associated with low-grade glioma, oligodendroglioma, ganglioglioma, pleomorphic xanthoastrocytoma, and dysembryoplastic neuroepithelial tumor (DNET).1 Seizure incidence is estimated to be 75% to 100% in children and adults who have both DNET and low-grade astrocytomas.1
As for causes by location, the authors note that there is a high risk of seizures with tumors affecting the temporal lobe and those having cortical involvement. They also found that cortical localization, tumor recurrence and glial histology present additional seizure risk factors.1
There are other factors that can lead to seizures in pediatric patients with a primary brain tumor, such as structural abnormalities caused by the tumor or as a result of surgery. There could be toxicity resulting from treatment. Patients with a history of radiation dose 30 Gy or higher to a cortical region of the brain have double the risk of developing seizure activity as a late effect of treatment.1
The authors continue, “Concurrent treatment with medications may also reduce seizure threshold. This list includes antidepressants, neuroleptics, antibiotics, and intrathecal or intra-arterial chemotherapy, all of which can make children with brain tumors more susceptible to having a seizure. Finally, seizures may result from secondary complications, such as infections, bleeding, cerebrovascular disease, or inflammation, which may decrease seizure threshold, or there may be spontaneous emergence of seizures in susceptible individuals over time.”1
Ullrich and her group hope their results aid in the early identification and management of pediatric patients who are at the highest risk for seizure activity.
1. Ullrich NJ, Pomeroy SL, Kapur K, Manley PE, Goumnerova LC, Loddenkemper T. Incidence, risk factors, and longitudinal outcome of seizures in long-term survivors of pediatric brain tumors [published online ahead of print August 31, 2015]. Epilepsia. 2015;56(10):1599-1604. doi:10.1111/epi.13112.