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Indication of ictal propagation using single pulse electrical stimulation evoked early responses

Keizer, D. (2015) Indication of ictal propagation using single pulse electrical stimulation evoked early responses.

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Abstract:Early responses (<100ms) evoked by single pulse electrical stimulation (SPES) of the epileptic brain are thought of as physiological phenomena. This study investigates their relevance with respect to ictal propagation patterns. SPES and seizure data from eight patients were recorded with a sampling frequency of 512 Hz. Stimulation consisted of ten monophasic pulses on adjacent electrodes with a pulse width of 1 ms and a frequency of 0.2 Hz. Stimulus intensity varied between 8-4 mA depending on the occurrence of pain, twitches or after-discharges. A Wiener filter based algorithm removed stimulation artefacts and automatically detected responses. For each patient a recording of a single stereotypical, clinical seizure was obtained. Ictal propagation was marked by consensus of three experienced epileptologists. Sensitivity, specificity and predictive values for early responses were calculated with respect to the witnessed ictal propagation pattern. Our results show high mean specificity 0.91 (range 0.75-1.00) and a lower mean specificity 0.37 (range 0.21-0.65). However, in cases of low sensitivity we did find high positive predictive values for the early responses occurred, 0.68 (range 0.45-1.00). The mean negative predictive value was 0.73 (range 0.54-0.90). Our results suggest a relationship between early responses and ictal propagation patterns.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Technical Medicine MSc (60033)
Awards:American Epilepsy Society Young Investigator Award
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