Behavioral toxicity associated with antiepileptic drugs: concepts and methods of assessment

The BTB designed for the VA Epilepsy Cooperative Study is a conceptually organized and practical set of test procedures that can be utilized to assess change in the areas of motor integration, visual perception, speech and language, and mood that might be attributable to AED therapy. If the data warrant, these categories can be compressed into motor, attention-concentration, and mood. The unique methodological advantages of the VA Epilepsy Cooperative Study provide an opportunity to determine empirically the occurrence of behavioral toxicity for specific AED. The advantage of the BTB is the capacity to measure change from an objective baseline over an extended period during chronic AED treatment. The disadvantages are the requirements for apparatus, trained technicians, and additional time for the patient, which now limit its use to research. If BTB data confirm its sensitivity to behavioral toxicity often unappreciated during a neurological exam, the BTB will become a useful clinical tool. Additionally, a common vocabulary for communicating behavioral toxicity may emerge. This optimistic picture is presented with the simultaneous acknowledgment that a clear solution to the problem lies in accumulation of data in future studies which will have had the opportunity to examine the forthcoming results of this multicenter study.