Lecture: profile of risks and benefits of new antiepileptic drugs in brain tumor-related epilepsy

The New Antiepileptic Drugs: Their Neuropharmacology and Clinical Indications

The administration of antiepileptic drugs (AEDs) is the first treatment of epilepsy, one of the most common neurological diseases. Therapeutic guidelines include newer AEDs as front-line drugs; monotherapy with new AEDs is delivered in Japan. While about 70% of patients obtain good seizure control by taking one to three AEDs, about 60% experience adverse effects and 33% have to change drugs. Compared to traditional AEDs, the prolonged administration of new AEDs elicits fewer adverse effects and fewer drug interactions and their teratogenicity may be lower. These characteristics increase drug compliance and allow combination therapy for drug-resistant epilepsy, although the antiepileptic effects of the new AEDs are not greater than of traditional AEDs. Comorbidities are not rare in epileptics; many adult patients present with stroke and brain tumors. In stroke patients requiring risk control and in chemotherapy-treated brain tumor patients, their fewer drug interactions render the new AEDs advantageous. Also, new AEDs offer favorable side benefits for concurrent diseases and conditions. Patients with stroke and traumatic brain injury often present with psychiatric/behavioral symptoms and cognitive impairment and some new AEDs alleviate such symptoms. This review presents an outline of the new AEDs used to treat adult patients based on the pharmacological activity of the drugs and discusses possible clinical indications from the perspective of underlying causative diseases and comorbidities.

Seizures in children with dysembryoplastic neuroepithelial tumors of the brain--A review of surgical outcomes across several studies

PURPOSE

In children and adolescents, dysembryoplastic neuroepithelial tumors (DNETs) of the brain present with seizures almost 100% of the time, potentially creating significant long-term morbidity and disability despite the generally indolent course of the lesion. These tumors also tend to be quite resistant to anti-epileptic drugs which, themselves, can be associated with long-term side effects and resultant disability. Many clinicians advocate early surgical resection of these lesions, but how effective this approach is, and how aggressive tumor removal should be, continues to be debated.

METHODS

We performed a systematic review of the relevant literature to identify all reports of DNET resections in pediatric patients published over the past 20 years. In all, over 3000 MEDLINE abstracts were reviewed, ultimately resulting in 13 studies with 185 pediatric DNET patients to review.

RESULTS

Surgical resection of the lesion was effective at improving seizures in over 98% of patients and at achieving long-term seizure freedom in 86%. Surgical resection of DNETs also appeared to be quite safe, with no reported perioperative deaths and an overall rate of postoperative complications of 12%; the vast majority of these complications were transient.

CONCLUSIONS

Total gross resection of the lesion was the only factor statistically correlated with long-term seizure freedom (r = 0.63, p = 0.03). However, data remain lacking regarding whether this translates into more extensive procedures-like brain mapping and partial lobectomies-being any more effective than simple lesionectomies alone. Further research is clearly needed to address this and other crucial questions.

The role of levetiracetam in treatment of seizures in brain tumor patients

Levetiracetam, trade name Keppra, is a new second generation antiepileptic drug that is being increasingly used in brain tumor patients. In patients suffering with brain tumors, seizures are one of the leading neurologic complications being seen in more than 30% of patients. Unlike other antiepileptic drugs, levetiracetam is proposed to bind to a synaptic vesicle protein inhibiting calcium release. Brain tumor patients are frequently on chemotherapy or other drugs that induce cytochrome P450, causing significant drug interactions. However, levetiracetam does not induce the P450 system and does not exhibit any relevant drug interactions. Intravenous delivery is as bioavailable as the oral medication allowing it to be used in emergency situations. Levetiracetam is an attractive option for brain tumor patients suffering from seizures, but also can be used prophylactically in patients with brain tumors, or patients undergoing neurological surgery. Emerging studies have also demonstrated that levetiracetam can increase the sensitivity of Glioblastoma tumors to the chemotherapy drug temozolomide. Levetiracetam is a safe alternative to conventional antiepileptic drugs and an emerging tool for brain tumor patients combating seizures.

[Epilepsy in the elderly]

BACKGROUND

Diagnostic work-up and treatment of patients who have developed epilepsy after the age of 65 can both be difficult. Epilepsy is one of the most common neurological conditions in the elderly, and the incidence of de novo geriatric epilepsy is rising. The aim of this review is to provide guidance on the management of epilepsy in this patient group.

METHOD

The review is based on a discretionary selection of original articles and reviews found in PubMed using the search term combination 'epilepsy' and 'elderly', and the authors' personal experience.

RESULTS

The seizures, which are most commonly of the focal type, are not infrequently overlooked or misdiagnosed. Cerebrovascular disease is the underlying cause of about half of the cases. When selecting an anticonvulsant, it is important to take age-related physiological changes and comorbidities into consideration. Because elderly patients have a narrower therapeutic window than younger persons and greater susceptibility to cognitive and other side effects, a low starting dose and slower dose titration are particularly important.

INTERPRETATION

The results of studies of young epilepsy patients cannot be extrapolated to apply to elderly patients. More studies directly targeting this patient population are therefore needed. As a general rule, we do not recommend starting on enzyme-inducing drugs such as phenytoin, phenobarbital and carbamazepine, partly because of their high interaction potential.