PracticeUpdate Neurology February 2019

EDITOR’S PICKS 17

Novel Method to Distinguish Convulsive Epileptic and Psychogenic Nonepileptic Seizures Epilepsia Take-home message • The use of wrist-worn accelerometer devices (ACM) is on the rise in clinical medicine to help facilitate diagnosis based on data from such devices. Previous studies have shown ACM to be an effective tool in detecting convulsive seizures. In this study, the authors present an alternate approach for differentiation of generalized tonic–clonic seizures (GTCS) and psychogenic nonepileptic seizures (PNES) using a wrist-worn ACM-based device. They used two indices, tonic index (TI) and dispersion decay index (DDI), that incorporate the motor symptomatology of GTCS and PNES. The device correctly differentiated 42 of 44 PNES (sensitivity, 95.45%) and 37 of 39 GTCS events (specificity, 94.87%) from 7 and 12 patients, respectively. • The authors present strong data to suggest that wrist-worn devices that are set up to identify the correct features in motor symptomatology may provide an accurate, low-cost, and very practical alternative to differentiate PNES from GTCS, a challenge that is very persistent in the current clinical settings. Omar Khan MD Abstract

OBJECTIVE To investigate the characteristics of motor manifestation during convulsive epileptic and psychogenic nonepileptic seizures (PNES), captured using a wrist-worn accelerometer (ACM) device. The main goal was to find quantitative ACM features that can differentiate between con- vulsive epileptic and convulsive PNES. METHODS In this study, motor data were recorded using wrist-worn ACM-based devices. A total of 83 clinical events were recorded: 39 generalized tonic-clonic seizures (GTCS) from 12 patients with epilepsy, and 44 convulsive PNES from 7 patients (one patient had both GTCS and PNES). The tem- poral variations in the ACM traces corresponding to 39 GTCS and 44 convulsive PNES events were extracted using Poincaré maps. Two new indi- ces-tonic index (TI) and dispersion decay index

(DDI)-were used to quantify the Poincaré-derived temporal variations for every GTCS and convul- sive PNES event. RESULTS The TI and DDI of Poincaré-derived tem- poral variations for GTCS events were higher in comparison to convulsive PNES events (P < 0.001). The onset and the subsiding patterns captured by TI and DDI differentiated between epileptic and convulsive nonepileptic seizures. An automated classifier built using TI and DDI of Poincaré-derived temporal variations could correctly differentiate 42 (sensitivity: 95.45%) of 44 convulsive PNES events and 37 (specificity: 94.87%) of 39 GTCS events. A blinded review of the Poincaré-derived temporal variations in GTCS and convulsive PNES by epileptologists differentiated 26 (sensitivity: 70.27%) of 44 PNES

events and 33 (specificity: 86.84%) of 39 GTCS events correctly. SIGNIFICANCE In addition to quantifying the motor manifestationmechanismof GTCS and convulsive PNES, the proposed approach also has diagnostic significance. The new ACM features incorporate clinical characteristics of GTCS and PNES, thus providing an accurate, low-cost, and practical alter- native to differential diagnosis of PNES. Novel Features for Capturing Temporal Variations of Rhythmic Limb Movement to Distinguish Convulsive Epileptic and Psychogenic Nonepileptic Seizures. Epilepsia 2018 Dec 09;[EPub Ahead of Print], S Kusmakar, C Karmakar, B Yan, et al. www.practiceupdate.com/c/77571

VOL. 4 • NO. 1 • 2019