Background: Epilepsy is a chronic neurological disease characterised by recurrent episodes of involuntary movement called seizures. Seizures are the physical representation of excessive and disorganised electric impulses of the neurons.
Objectives: The discovery of cortical spreading depression (CSD)
80 years ago, by Leao, was intimately connected to epilepsy research performed.
In this study, it is found that monitoring of brain hemodynamics, metabolic,
ionic and electrical activities are very similar in the two pathophysiological
events. Here, the study presents the coupling between epilepsy and cortical
spreading depression while monitoring mitochondrial NADH together with other
brain physiological parameters in real time in vivo.
Methods: Rats and Mongolian gerbils were used in three models of
induction of epilepsy, namely injection of Metrazol, exposure of the rats to
hyperbaric oxygenation in a pressure chamber and using a strain of gerbils that
are developing seizures spontaneously. Brain oxygen levels, mitochondrial NADH,
extracellular potassium levels, DC steady potential and EEG in the very
slightly anaesthetized animals were monitored. Preliminary monitoring of
neurosurgical patients was performed in the current study.
Results: The effects of locally applied Metrazol were tested in
awake animals. The Metrazol (100 mg/ml) was applied epidurally using the
cannula. The most typical response to Metrazol occurs 3-5 min after the
administration of the drug. The effects of Metrazol on brain metabolism and its
impact upon the oxidation-reduction state of NADH are of great interest. The
results could be summarised as follows: 1. In almost all animal models tested,
cortical spreading depression was developed and recorded 1-3 minutes after
seizure activity. 2. The mitochondrial NADH redox state was more oxidised
during the two events. 3. The oxidation of NADH during the CSD was 3-4 times
relative to the seizure interval. 4. The increase in extracellular potassium
levels was also 3-4 times higher during the CSD event. 4. The monitored
head-injured patient provided results that were in very high correlation with
the animal studies' results.
Conclusions: Under the two recorded events, a clear correlation
between the process of oxygen(energy) demand or consumption and oxygen(energy)
supply was found. The results suggest that the accumulation of extracellular
potassium during the epileptic activity is probably the trigger for the
development of CSD in the 3 models used as well as in the neurosurgical patient
tested.
Author
(s) Details
Avraham
Mayevsky
The Mina & Everard Goodman Faculty of Life Sciences and the
Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan
University, Ramat-Gan 5290002, Israel.
Please see the book here:- https://doi.org/10.9734/bpi/msraa/v5/5448
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