Background: The new definition of a transient ischemic attack (TIA) makes it more difficult to distinguish it from an inhibitory seizure (IS). Purpose: The present study compares the characteristics of patients with an IS to those with a TIA, taking into account the old and the new definition of a TIA. Patients and Methods: The clinical characteristics and the electroencephalogram (EEG) findings of 25 patients with an IS were compared to 252 patients with a TIA according to the old definition. Subgroups of 10 patients with an IS without structural lesions and 195 TIA patients according to the new definition were also analyzed. The differential diagnostic clues were examined. Results: Differences in age, gender distribution and vascular risk factors were observed only when comparing the overall patient groups. However, these differences disappeared when the subgroups were analyzed. Temporary speech disturbance, associated with some partial amnesia for the event, was the most common clinical presentation of an IS. Additionally, specific and nonspecific postictal EEG abnormalities were observed in the majority of the IS patients, while the EEG was normal in more than 90% of the TIA patients. Conclusions: An IS must be suspected in a patient with a short temporary speech disturbance and partial amnesia for the event. In view of the new definition of a TIA, urgent EEG becomes mandatory in each patient with a brief episode of neurological dysfunction.

Keywords:
Inhibitory seizure, Transient ischemic attack, Differential diagnosis, Speech disturbances, Vascular risk factors, Electroencephalogram
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2009
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