Observation of psychogenic nonepileptic seizures (PNESs) during video-EEG represents the diagnostic gold standard for PNESs. Different provocative techniques have been used to increase PNES frequency during EEG. These techniques include placebo administration, suggestion strategies, or both. In order to avoid the appearance of deception, we investigated the following hypothesis: If patients with PNESs were informed about the possible reduction of seizure threshold caused by hyperventilation and photic stimulation prior to EEG without any other suggestive strategies, PNESs would occur more frequently. In total, 34 inpatients with a diagnosis of PNESs, who had been informed prior to EEG about the increased seizure risk during hyperventilation and photic stimulation (study group), and 80 "noninformed" patients (control group) were enrolled. Psychogenic nonepileptic seizures occurred significantly more often in the study group compared to controls (38% vs. 10.0%, p=0.001). Our results imply that simply providing correct and explicit information about provocation techniques substantially increased the PNES rate.
Keywords: EEG; Hyperventilation; PNES; Photic stimulation; Provocative techniques; Psychogenic nonepileptic seizures.
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