Cluster analysis of clinical seizure semiology of psychogenic nonepileptic seizures

Purpose: To develop an objective classification of psychogenic nonepileptic seizures (NES) based on cluster analysis of clinical seizure semiology. Methods: We studied the clinical seizure semiology in 27 patients with psychogenic NES documented by prolonged video-EEG monitoring. We analyzed the following clinical symptoms: clonic and hypermotor movements as well as trembling of the upper and/or lower extremities, pelvic thrusting, head movements, tonic posturing backward of the head, and falling. We used cluster analysis to identify symptoms occurring together in a systematic way and thus tried to achieve a clinical classification of psychogenic NES. Results: We could identify three symptom clusters. Cluster I was characterized by clonic and hypermotor movements of the extremities, pelvic thrusting, head movements, and tonic pos- turing of the head, and therefore was named "psychogenic motor seizures." Cluster ? comprised trembling of the upper and lower extremities and was termed "psychogenic minor motor or trembling seizures." Cluster 3 consisted of falling to the floor as the only symptom and was referred to us "psychogenic atonic seizures." Conclusions: Our study represents the first study to analyze the clinical semiology of psychogenic NES by cluster analysis, which should be useful fur an objective classification of psychogenic NES. This classification should allow both a better characterization of psychogenic NES and an easier differential diagnosis against specific epileptic seizures.