Preictal pseudosleep: A new finding in psychogenic seizures

Background and objective: The diagnosis of psychogenic seizures (pseudoseizures) may be difficult and usually rests on video-EEG monitoring. We observed that pseudoseizures often arise out of a state that we termed preictal pseudosleep. The objective of this study was to investigate this potential new sign in pseudoseizures. Methods: We prospectively studied all patients who underwent noninvasive monitoring over a 10-month period. Patients were monitored for a duration of 1 to 19 days (mean 4.9), and were divided into two groups: pseudoseizures and epileptic seizures. Patients with both conditions were excluded. Preictal pseudosleep was defined as a state that resembled normal sleep by behavioral criteria alone (i.e. patient motionless and eyes closed), while EEG showed evidence of wakefulness (alpha rhythm, active EMG, and rapid eye movement). This state had to be sustained for at least 1 minute before clinical onset. Results: Patients had 1 to 25 (mean 7) clinical events recorded. Preictal pseudosleep was seen in 10 of 18 patients with pseudoseizures and in none of 39 patients with epileptic seizures, yielding a sensitivity of 56% and a specificity of 100% for pseudoseizures. Conclusion: Because of a high specificity, preictal pseudosleep may be a useful adjunctive finding to support the diagnosis of pseudoseizures.