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Seizures are a common symptom in patients with brain tumors, impacting significantly on their quality of life. They represent a major cause of morbidity, particularly if they are intractable. The incidence of seizures in patients with brain tumors varies between 30 and 70% and is influenced primarily by tumor histology and location [1,2]. However, the incidence of brain tumors in patients with epilepsy is around 4% [3,4]. Although any patient with a brain tumor can develop seizures, this review will be restricted to the unique aspects of seizures in patients with gliomas. Low-grade gliomas (LGGs) present more frequently with seizures (60-85%) than high-grade gliomas (20-40%) or brain metastases (15-20%) [1,2]. Seizure management represents a challenge in the context of gliomas because these neoplasms are never completely resectable due to their infiltrative nature and frequent location near eloquent areas of brain. The use of anticonvulsants in patients with gliomas can aggravate neurocognitive toxicities associated with the tumor and its treatment. The arrival of a new generation of anticonvulsants has made selection of the most appropriate agent(s) complex for maximizing efficacy and reducing toxicities in patients with gliomas. We will review important factors related to seizure control in patients with gliomas, including the role of anticonvulsant prophylaxis, the impact of surgery and radiotherapy on seizure control, the management of intractable seizures, the tapering of anticonvulsants, the potential interactions of anticonvulsants with other agents commonly used in brain tumor patients including antineoplastic agents, the emerging concept of resistance to antiseizure drugs and the potential antitumoral activity of selected anticonvulsants such as valproic acid. The management of seizures in patients with gliomas is often challenging but crucial to the optimization of the quality of life in this patient population.
Characteristics of seizures in patients with gliomas
Seizures represent the most frequent presentation of LGG (∼80%) [5]. In the case of high-grade gliomas, they occur in approximately one-half of grade III gliomas and one-fourth of glioblastomas [6]. Location heavily influences seizure incidence, as cortical tumors are more epileptogenic than deep white matter, basal ganglia or infratentorial neoplasms [7]. In addition to location, oligodendrogliomas and oligoastrocytomas (70-90% present with seizures) are significantly more epileptogenic than astrocytomas (15-90% present with seizures depending on the grade) [8,9]. The pathogenesis of epilepsy in...