Dennis B. Smith

Pseudoseizures Diagnostic evaluation

A prospective study of pseudoseizures using prolonged video-electroencephalographic (EEG) recording was carried out in 60 patients. Of 33 patients with episodes of uncertain mechanism, a diagnosis based on recorded episodes was made in 18 (55%). Twelve (36%) had pseudoseizures; 6 (18%) had epileptic seizures. Ten additional patients had epileptiform EEGs compatible with epilepsy. Of 27 patients with presumably uncontrolled epileptic seizures, 4 (15%) had recorded pseudoseizures. Prediction of the nature of the episode by the admitting neurologist was accurate in 67% of cases. Determination from observations of unit personnel and neurologists was correct in less than 80% of episodes.These data suggest that pseudoseizures occur frequently in patients being evaluated for epilepsy or suspected epilepsy. The clinical differentiation between epileptic seizures and pseudoseizures is often inaccurate. This differentiation is facilitated by prolonged video-EEG recording.

A reliable method for localizing deep intracranial sources of the EEG

We have demonstrated the reliability of a noninvasive method for successfully localizing the intracranial origin of the EEG. The dipole localization method (DLM) is a computer-assisted, mathematical method based on electrical field theory and is similar to localization methods currently used by electrocardiologists. In 12 patients with intractable epilepsy who were being evaluated for surgery, a known current source was introduced between two adjacent depth electrodes. Using scalprecorded EEG only, DLM accurately and reliably localized the source to within 2 cm of the known origin in all instances where a discrete source was present. We conclude that DLM is a valid and reliable noninvasive method for localizing the intracranial source of some scalp-recorded EEG potentials, and that in some patients, use of this method may obviate the need for depth electrode implantation.

Historical perspective on the choice of antiepileptic drugs for the treatment of seizures in adults.

Although numerous reports have appeared in the literature over the past 100 years describing various antiepileptic drugs, it is not possible to justify preference for a particular drug to treat specific types of adult seizures. Since the introduction of bromides a century ago, numerous antiepileptic drugs have been developed. Four such drugs, carbamazepine, phenobarbital, phenytoin, and primidone, have been found to be effective and acceptably safe for management of partial and secondarily generalized seizures. However, no studies have demonstrated the superior efficacy of any one drug. Clinical selection of therapy often is based on expected or assumed risk or absence of specific side effects. This review of classic papers demonstrates inconclusive and conflicting information. A new approach to the comparative evaluation of the efficacy and toxicity of major antiepileptic drugs is needed.

Principles in designing clinical trials for antiepileptic drugs

The failure of previous studies to indicate clear differences in the relative seizure control and side effects of the major antiepileptic drugs has resulted from insufficient clinical trials or limitations in earlier studies. The principles for designing studies of the efficacy and toxicity of major antiepileptic drugs are outlined. These standards apply to the evaluation of new and old antiepileptic drugs used for all types of seizures in diverse populations.