Movement-based seizure detection.

This is a critical review and comment on the use of movement detection in epileptic seizures. The detection of rhythmic movement components, such as the clonic part of tonic-clonic seizures, is essential in all seizure detection based on movement sensors. Of the many available movement sensor types, accelerometric sensors are used most often. Eleven video-electroencephalographic (EEG) and 1 field study have been carried out. The results of these clinical trials depend on the population, study design, and seizure evolution. In video-EEG monitoring units, sensitivity for tonic-clonic seizures varied from 31% to 95%, and positive predictive value from 4% to 60%. In a field trial in a residential adult population with intellectual disability, sensitivity was 14% and positive predictive value was 82%, whereas in patients admitted to an epilepsy clinic, a bed sensor had a sensitivity of 84% (no positive predictive value was given). The algorithms using the "rhythmic movement" component at the end of a tonic-clonic seizure are reliable (few false-positive alarms) but miss less typical seizure patterns that are mostly present in people with associated brain development disturbances. Other modalities (heart rate and electromyography) are needed to increase the detection performance. Advanced accelerometric techniques allow us to gain greater insight into seizure evolution patterns, possibilities for neuromodulation, and the influence of antiepileptic drugs on specific seizure components.