Testing the ‘seizure scaffold’: What can experimental simulation tell us about functional seizures?

Introduction
It has been suggested for over 100 years that patterns of neurological symptoms and signs in functional neurological disorders may be shaped at a neural level by underlying ideas or preconceptions how neurological symptoms present. This study used experimental simulation to probe ideas about seizures in healthy volunteers, with a view to compare with features commonly observed in functional and epileptic seizure disorders.

Methods
Sixty healthy volunteers were instructed to simulate an epileptic seizure. The episodes were video-recorded and assessed by three qualified markers for the presence of clinical features commonly observed in functional seizures (FS), epileptic seizures, and syncope.

Results
Simulated seizures were hyperkinetic (83%), hypokinetic (7%), or staring (10%). Fifty-two percent had their eyes open and 45% eyes closed. Tremor was observed in 70%, while clonic jerking was only present in 17%. The majority of volunteers maintained a normal or floppy body posture. Head shaking side-to-side was observed in 38%, while guttural cries, stertorous breathing, tearfulness, and hyperventilation were absent in all volunteers.

Discussion
Our results suggest that simulated seizures not only resemble FS more closely than epileptic seizures but also show some important differences. Subjective seizure experiences in people with FS, not captured by this experimental simulation, remain a core determinant of semiology.