Discriminating between epileptic and nonepileptic events: The utility of hypnotic seizure induction

Purpose: To determine the validity of the Hypnotic Induction Profile (HIP) followed by seizure induction during continuous video-electroencephalographic (EEG) monitoring to discriminate between epileptic (EE) and nonepileptic events (NEE). Methods: Eighty-two patients admitted to the Stanford Comprehensive Epilepsy Center for differential diagnosis of seizure-like events were evaluated. Exclusion criteria included inability or refusal to complete the HIP, lack of a "typical" event, an IQ <70, present evidence of psychosis, or a physiological cause for NEE. Sixty-nine patients met these criteria. while undergoing continuous video-EEG monitoring, the patient completed an HIP, an inventory designed to measure the degree of hypnotizability, An attempt was then made to induce the patient's typical events under hypnosis by using a split-screen technique. An event without an EEG correlate was thought to represent an NEE. A diagnosis of NEE was made independently by the neurology team and was compared with results obtained with the hypnotic evaluation. Results: Results for patients with EE were compared with those with NEE and a group consisting of both EE/NEE. All patients with NEE were then contrasted with the EE group. HIP scores for the EE patients indicated lower hypnotizability than the NEE group and were statistically significant when NEE patients and those with NEE/EE were combined. The sensitivity of seizure induction in the diagnosis of NEE was 77%, with a specificity of 95%. Conclusions: The HIP coupled with seizure induction is a useful technique to aid in the diagnosis of patients with NEE. It is sensitive and specific, and it may provide the patient with a useful behavioral tool to control NEEs. It may also furnish a conduit for long-term treatment.