Quantified Analysis of Wrist and Trunk Movements Differentiates between Hypermotor and Automotor Seizures

Abstract

We have attempted to evaluate the movement characteristics of hypermotor and automotor seizures based on an observer-independent objective method. We included EEG and video recorded automotor (n=10) and hypermotor seizures (n=10) of 17 patients considered for resective epilepsy surgery, in whom the camera position was perpendicular to the trunk facing the camera in an upright position and wrist and trunk movements were continuously visible on the video recordings. The movements were quantified from the videos by analyzing all video frames during the entire seizure (25/s). Seizure duration, movement angular speed, movement extent and predominant frequencies (power spectral analysis) of the movements were analyzed (Wilcoxon rank sum test). Maximum speed (median 902 pixel/s vs. 223 pixel/s, p<0.001) and extent (median 45597 pixel2 vs. 2304 pixel2, p<0.001.) of the wrist movements were significantly faster and greater in hypermotor seizures than in automotor seizures. The extent of trunk movement was significantly greater in hypermotor seizures (median 4458.5 pixel2) than in automotor seizures (median 412.5 pixel2) (p<0.001). The analysis of wrist movement extent separated all automotor from hypermotor seizures. The analysis of maximum angular speed of the wrist movement showed that only one automotor seizure (585 pixel/s) was above the lowest maximum angular speed of wrist movements of hypermotor seizures (553 pixel/s). The predominant repetition rate of the automatisms in automotor seizures was ca. 1/s, whereas no predominant frequency of movements was observed in the hypermotor seizures. The duration of the automotor seizures (median 81±41s) was longer than that of the hypermotor seizures (69±54s) (p<0.04). The quantitative analysis of wrist and trunk movements provides objective measures for the differentiation of hypermotor and automotor seizures. This information is helpful for the classification of seizure types in patients considered for resective epilepsy surgery.