Quantitative movement analysis of extent of wrist movements identifies hypermotor seizures in a non-selected sample of focal epileptic motor seizures

To evaluate the sensitivity and specificity of a novel quantitative analysis of movements during epileptic seizures for the identification of different motor seizures.

We included 100 randomly selected videos of epileptic motor seizures recorded in the epilepsy monitoring unit in patients. Only videos were included, 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). Extent and angular speed (absolute maximum speed and mean speed) of trunk and relative wrist-trunk movements, and predominant frequencies (power spectral analysis) of the movements were analyzed. Sensitivity and specificity of the quantitative parameters in the identification of hypermotor and automotor seizures were calculated.

The minimum extent of relative wrist-trunk movement as defined by an earlier study on hypermotor seizures was used and identified objectively all hypermotor seizures (sensitivity 100%, specificity 70%). Extent of trunk movement misclassified only one hypermotor seizure (sensitivity 95%, specificity 80%). Absolute maximum speed of wrist movements identified 9 out of 14 hypermotor seizures (sensitivity 65%, specificity 94%). Mean wrist speed misclassified only one hypermotor seizure (sensitivity 95%, specificity 80%). Analysis of repetition rate had a low sensitivity (16%), but high specificity (100%) in detecting automotor seizures.

The observer independent quantitative analysis of ictal movements helps identify objectively hypermotor seizures, a seizure type more likely to be generated outside the temporal lobes.