Temporal behavior of seizures and interictal bursts in prolonged intracranial recordings from epileptic canines.
Epilepsy is a chronic disorder, but seizure recordings are usually obtained in the acute setting. The chronic behavior of seizures and the interictal bursts that sometimes initiate them is unknown. We investigate the variability of these electrographic patterns over an extended period of time using chronic intracranial recordings in canine epilepsy.



Continuous, yearlong intracranial electroencephalography (iEEG) recordings from four dogs with naturally occurring epilepsy were analyzed for seizures and interictal bursts. Following automated detection and clinician verification of interictal bursts and seizures, temporal trends of seizures, burst count, and burst-burst similarities were determined. One dog developed status epilepticus, the recordings of which were also investigated.



Multiple seizure types, determined by onset channels, were observed in each dog, with significant temporal variation between types. The first 14 days of invasive recording, analogous to the average duration of clinical invasive recordings in humans, did not capture the entirety of seizure types. Seizures typically occurred in clusters, and isolated seizures were rare. The count and dynamics of interictal bursts form distinct groups and do not stabilize until several weeks after implantation.



There is significant temporal variability in seizures and interictal bursts after electrode implantation that requires several weeks to reach steady state. These findings, comparable to those reported in humans implanted with the NeuroPace Responsive Neurostimulator System (RNS) device, suggest that transient network changes following electrode implantation may need to be taken into account when interpreting or analyzing iEEG during evaluation for epilepsy surgery. Chronic, ambulatory iEEG may be better suited to accurately map epileptic networks in appropriate individuals.
Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.
Hoameng
H
Ung
Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.|Penn Epilepsy Center, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.
Kathryn A
KA
Davis
Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.
Drausin
D
Wulsin
Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.
Joost
J
Wagenaar
Department of Statistics, University of Washington, Seattle, Washington, U.S.A.
Emily
E
Fox
School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.
John J
JJ
McDonnell
Department of Veterinary Clinical Sciences, University of Minnesota, St. Paul, Minnesota, U.S.A.
Ned
N
Patterson
School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.
Charles H
CH
Vite
Department of Neurology, Mayo Clinic, Rochester, Minnesota, U.S.A.
Gregory
G
Worrell
Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.|Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.|Penn Epilepsy Center, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.
Brian
B
Litt
D000818:Animals; D001921:Brain / Q000503:physiopathology*; D058256:Brain Waves / Q000502:physiology*; D004285:Dogs; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology* / Q000662:veterinary*; D005260:Female; D008137:Longitudinal Studies; D008297:Male

EEG
; Bursts; Canine; Intracranial; Seizure