Cell Swelling, Seizures and Spreading Deprssion: An Impedance Study
Journal article, 2006

The cellular processes that take place during the transition from pre-seizure state to seizure remain to be defined. In this study in awake, paralyzed rats, we used an electrical impedance measure of changes in extra-cellular intracranial volume to estimate changes in cell size in acute models of epilepsy. Animals were prepared with extradural electroencephalographic (EEG)/impedance electrodes and a venous catheter. On a subsequent day, animals were paralyzed, ventilated and treated with picrotoxin, kainic acid or fluorocitrate in doses that usually induce epileptiform discharges. We now report that increases in baseline impedance were induced by kainic acid and smaller increases by picrotoxin. We also demonstrated that epileptiform discharges were preceded by small, accelerated increases in impedance. Increases in baseline impedance were highly correlated with increases in power of non-ictal high frequency EEG activity. Seizures were accompanied by increases in impedance and all treatments induced transient, relatively large, increases in impedance often associated with unilateral reductions in low frequency EEG, likely periods of spreading depression. We conclude: cerebral cells swell in convulsant models of epilepsy, that there are pre-ictal accelerations in cell swelling, and that spreading depression-like events are frequently associated with seizures.




cerebral cortex

kainic acid



Torsten Olsson

Chalmers, Signals and Systems, Signalbehandling och medicinsk teknik, Biomedical Signals and Systems

Marita Broberg

University of Gothenburg

Kenneth Pope

Flinders University

Andrew Wallace

Flinders University

Lorraine Mackenzie

Flinders University

Fredrik Blomstrand

University of Gothenburg

Michael Nilsson

University of Gothenburg

John Willoughby

Flinders University


0306-4522 (ISSN)

Vol. 140 2 505–515-

Subject Categories

Medical Laboratory and Measurements Technologies




More information