Semiautomatic quantification of spiking in patients with continuous spikes and waves in sleep: Sensitivity to settings and correspondence to visual assessment

Peltola, M.E.; Palmu, K.; Liukkonen, E.; Gaily, E.; Vanhatalo, S.

doi:10.1016/j.clinph.2011.12.001

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Semiautomatic quantification of spiking in patients with continuous spikes and waves in sleep: Sensitivity to settings and correspondence to visual assessment

M.E. Peltola
- Department of Clinical Neurophysiology, Turku University Hospital, Finland
- Epilepsy Unit, Department of Pediatric Neurology, Helsinki University Central Hospital, Finland
- Corresponding author at: Epilepsy Unit, Helsinki University Central Hospital, P.O. Box 280, 00029 HUS, Finland. Tel.: +358 9 471 80408; fax: +358 9 471 80413.
K. Palmu
- Department of Children’s Clinical Neurophysiology, Helsinki University Central Hospital, Finland
- Department of Biomedical Engineering and Computational Science, School of Science, Aalto University, Espoo, Finland
E. Liukkonen
- Epilepsy Unit, Department of Pediatric Neurology, Helsinki University Central Hospital, Finland
E. Gaily
- Epilepsy Unit, Department of Pediatric Neurology, Helsinki University Central Hospital, Finland
S. Vanhatalo
- Department of Children’s Clinical Neurophysiology, Helsinki University Central Hospital, Finland
- Department of Neurological Sciences, University of Helsinki, Finland

Accepted 2 December 2011. published online 06 January 2012.
Corrected Proof

Highlights

► An objective paradigm for quantification of continuous spikes and waves in sleep (CSWS) is needed for both scientific and clinical use. ► Semiautomatic quantification of spike index (SI) with appropriate parameter settings is a robust and a promising tool. ► SI of the first hour of sleep is representative of the whole night SI.

Abstract

Objective

To define the optimal analysis protocol for semiautomatic quantification of spike index (SI) in continuous spikes and waves in sleep (CSWS).

Methods

Ten overnight EEGs (nine patients) with abundant spiking were used to quantify SI with a previously published semiautomatic quantification based on spike detection with BESA software. We studied (i) dependency of SI on maximal interspike interval (maxISI) defining the continuous discharge, (ii) sensitivity of SI to variations in the spike search protocol, and (iii) stability of SI over time. Finally, the semiautomatic method was compared with the quantification based on visual scoring by two neurophysiologists.

Results

MaxISI of 3s appeared to yield the best combination of sensitivity and stability in SI quantification. The SI of the first hour of sleep did not differ significantly from the SI of the whole night. Mean error of the semiautomatic method compared to visual scoring was only seven percentage units.

Conclusions

Semiautomatic quantification of SI functions well with maxISI of 3s, and the first hour of sleep represents the whole night SI with a clinically relevant accuracy.

Significance

This method opens a possibility for objective quantification of near-continuous epileptiform spiking during sleep, and it supports the use of shorter epochs for quantitative assessment of CSWS.

Keywords: CSWS, Electrical status epilepticus during sleep, ESES, Spike index, Automated EEG analysis