Epilepsia
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Review Comparative Study
A comment on the efficacy of valproate in the treatment of partial seizures.
Discrepancies in the findings of studies sponsored by the Department of Veterans Affairs (VA) in the United States and the Medical Research Council (MRC) in the United Kingdom concerning the efficacy of valproate (VPA) in controlling simple or complex partial seizures, particularly those without secondarily generalized seizures, were reviewed. It was noted that the two studies differed with respect to their subjects' pretreatment seizure frequency. The frequency of complex partial seizures before treatment was obviously greater in the VA study, where carbamazepine (CBZ) provided better seizure control than VPA. Based on other comparative and non-comparative studies as well as the author's over 20 years of experience in the use of VPA in a tertiary epilepsy clinic, it is suggested that although VPA may be effective in controlling both the secondarily generalized seizures of symptomatic localization-related epilepsies and the generalized tonic-clonic seizures of idiopathic and, if not always, symptomatic generalized epilepsies, the efficacy of VPA in controlling simple or complex partial seizures is likely limited to patients with infrequent seizures.
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Vigabatrin, lamotrigine, and oxcarbazepine are three of the many new antiepileptic drugs (AEDs) already registered in several countries that highlight some of the typical problems and prejudices of new AEDs. Both the therapeutic action and the side-effect profiles of new AEDs are only basically known with marketing. ⋯ All three have some effect on focal seizures, but their clinical spectrum probably will turn out to be by no means uniform. These three AEDs are, in general, well tolerated, but it would be premature to compare their safety with traditional AEDs as one must be prepared for rare or delayed untoward effects that may be discovered later, as occurred with some older AEDs.
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The intracarotid amobarbital procedure and direct cortical stimulation are commonly used techniques for functional mapping in candidates for epilepsy surgery. The role of these two procedures has been challenged recently. Emerging technologies recently applied to functional mapping include optical imaging, functional positron emission tomography studies, transcranial magnetic stimulation, magnetoencephalography, and fast magnetic resonance imaging. Studies have used these new technologies and the potential for these procedures to replace the established but more invasive techniques is being considered.
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Review of randomized controlled trials (RCTs) shows that valproate (VPA) is effective against partial seizures with or without becoming secondarily generalized. A number of RCTs show little difference in the efficacy of VPA and carbamazepine in this patient group, particularly where patients are randomized at the time of diagnosis. The length of time that it has taken to arrive at these conclusions emphasizes the importance of large active-controlled RCTs at an early stage in drug development in informing clinical practice.
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Among some 14 new antiepileptic drugs (AEDs), those most extensively tested in humans include felbamate (FBM), gabapentin (GBP), lamotrigine (LTG), oxcarbazepine (OCBZ), vigabatrin (VGB), and zonisamide (ZNS). All are currently marketed in some but not all countries. Although no large, comparative studies on efficacy have been conducted, all of these new AEDs are effective in adult localization-related epilepsies, and some have activity in specific syndromes. ⋯ Half-life of ZNS is 27-36 h. ZNS daily dosage is 400-600 mg. ZNS has been effective in some cases of Baltic myoclonic epilepsy.