title: Detecting rare events using extreme value statistics applied to epileptic convulsions in children.
abstract: OBJECTIVE
  Nocturnal home monitoring of epileptic children is often not feasible due to the cumbersome manner of seizure detection with the standard method of video electroencephalography monitoring. The goal of this paper is to propose a method for hypermotor seizure detection based on accelerometers that are attached to the extremities.
  
  
  METHODS
  Supervised methods that are commonly used in literature need annotation of data and hence require expert (neurologist) interaction resulting in a substantial cost. In this paper an unsupervised method is proposed that uses extreme value statistics and seizure detection based on a model of normal behavior that is estimated using all recorded and unlabeled data. In this way the expensive interaction can be avoided.
  
  
  RESULTS
  When applying this method to a labeled dataset, acquired from 7 patients, all hypermotor seizures are detected in 5 of the 7 patients with an average positive predictive value (PPV) of 53%. For evaluating the performance on an unlabeled dataset, seizure events are presented to the system as normal movement events. Since hypermotor seizures are rare compared to normal movements, the very few abnormal events have a negligible effect on the quality of the model. In this way, it was possible to evaluate the system for 3 of the 7 patients when 3% of the training set was composed of seizure events. This resulted in sensitivity scores of 80%, 22% and 90% and a PPV of 89%, 21% and 44% respectively. These scores are comparable with a state-of-the-art supervised machine learning based approach which requires a labeled dataset.
  
  
  CONCLUSIONS
  A person-dependent epileptic seizure detection method has been designed that requires little human interaction. In contrast to traditional machine learning approaches, the imbalance of the dataset does not cause substantial difficulties.
authors.affiliation: Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium. Electronic address: stijn.luca@kuleuven.be.
authors.forename: Stijn
authors.initials: S
authors.lastname: Luca
authors.affiliation: Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium; iMinds Future Health Department, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Karsmakers
authors.affiliation: Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium; iMinds Future Health Department, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium.
authors.forename: Kris
authors.initials: K
authors.lastname: Cuppens
authors.affiliation: Computer Science Department, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium.
authors.forename: Tom
authors.initials: T
authors.lastname: Croonenborghs
authors.affiliation: University Hospital of Antwerp, Wilrijkstraat 10, 2650 Edegem, Belgium.
authors.forename: Anouk
authors.initials: A
authors.lastname: Van de Vel
authors.affiliation: University Hospital of Antwerp, Wilrijkstraat 10, 2650 Edegem, Belgium; Epilepsy Centre for Children and Youth Pulderbos, Reebergenlaan 4, 2242 Zandhoven, Belgium.
authors.forename: Berten
authors.initials: B
authors.lastname: Ceulemans
authors.affiliation: Epilepsy Centre for Children and Youth Pulderbos, Reebergenlaan 4, 2242 Zandhoven, Belgium; University Hospital Leuven, Herestraat 49, 3000 Leuven, Belgium.
authors.forename: Lieven
authors.initials: L
authors.lastname: Lagae
authors.affiliation: Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium; iMinds Future Health Department, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium.
authors.forename: Sabine
authors.initials: S
authors.lastname: Van Huffel
authors.affiliation: Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium; iMinds Future Health Department, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Vanrumste
mesh_terms: D002648:Child; D004827:Epilepsy / Q000503:physiopathology*; D006801:Humans; D015233:Models, Statistical; D012984:Software
keywords: Accelerometers; Epileptic; Extreme value theory; Hypermotor seizures; Unbalanced data; Unsupervised