Relationship between the cortical evoked potential and local cortical blood flow following acute middle cerebral artery occlusion in the baboon

doi:10.1016/0014-4886(74)90112-5

Experimental Neurology

Volume 45, Issue 2, November 1974, Pages 195-208

https://doi.org/10.1016/0014-4886(74)90112-5 Get rights and content

Abstract

In most experimental studies of the effects of ischemia on CNS electrical activity, the ischemia produced has been total. The present experiments, however, were designed to establish quantitatively the changes in electrical activity corresponding to different degrees of cerebral ischemia. The somatosensory evoked potential was measured at various sites on the exposed postcentral gyrus of the anesthetized baboon, and cortical blood flow was assessed in the region of the evoked potential electrode by the highly focal method of hydrogen clearance. The technique of middle cerebral artery occlusion was used to reduce blood flow over the hemisphere. Following occlusion of the artery, the amplitude of the evoked potential typically diminished steadily at a rate depending on the level of residual local blood flow. The rate of depression of the evoked potential amplitude (expressed in units of percent of control per minute) was highly and significantly correlated with the residual flow (r = −0.95, P < 0.001), which indicated a linear relationship between these variables, the regression line intercepting the flow axis at 15.2 ml/100g/min. The data also strongly suggested a threshold-type relationship between the amplitude of the evoked potential and the local blood flow: If the flow was greater than about 16 ml/100g/min the evoked potential was not affected, but at flows less than about 12 ml/100g/min the evoked potential was abolished.

References (29)

H. Collewijn et al.
Membrane potential of cerebral cortical cells during spreading depression and asphyxia
Exp. Neurol.
(1966)
K-A. Hossmann
Cortical steady potential, impedance and excitability changes during and after total ischemia of cat brain
Exp. Neurol.
(1971)
K-A. Hossmann et al.
Effect of ischemia on the function of the sensorimotor cortex in cat
Electroenceph. Clin. Neurophysiol.
(1971)
A. Przybylski
Activity pattern of visceral cortex neurons during asphyxia
Exp. Neurol.
(1971)
L. Symon et al.
Lactic acid efflux from ischaemic brain
J. Neurol. Sci.
(1972)
G. Boysen et al.
Effect of mechanical rCBF reduction on EEG in man
J.B. Brierley et al.
Moderate hypoxic ischemia irreversibly damages rat brain in 30 minutes
B. Chance
Cellular oxygen requirements
H. Collewijn et al.
Intracellular recording from cat spinal motoneurones during acute asphyxia
J. Physiol. (London)
(1966)
N.W.C. Dorsch et al.
Intracranial pressure changes in acute ischaemic regions of the primate hemisphere

W. Erdmann et al.

Tissue pO₂ and cell function in the microarea of the brain during hypoxia

E.F. Evans

Discussion report

Neurosciences Research Program

(1969)

R.G. Grossman et al.

The relationship between cortical electrical activity, cerebral perfusion pressure and cerebral blood flow during increased intracranial pressure

J. Harvey et al.

Occlusion of the middle cerebral artery

Arch. Neurol. (Chicago)

(1951)

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TAO has proved to be a useful tool in aneurysm surgery by decreasing the pressure inside the aneurysm, facilitating dissection and preventing procedural complications [6,7,12]. TAO’s safety is improved when it is associated with other techniques, such as intraoperative neurophysiological monitoring (IONM) of somatosensory evoked potentials (SSEPs) [13–17] and intraoperative hypothermia [18–20]. Drugs that reduce the cellular metabolic demand during the occlusion have also been used with the same aim, but the neuroprotective effect in short- and long-term is still controversial [8,21–32].
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¹: Mr. Crockard and Dr. Pasztor were the recipients of Wellcome Research Fellowships. This study was supported by the Medical Research Council and the Wellcome Foundation.

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Relationship between the cortical evoked potential and local cortical blood flow following acute middle cerebral artery occlusion in the baboon

Abstract

Exp. Neurol.

Exp. Neurol.

Electroenceph. Clin. Neurophysiol.

Exp. Neurol.

J. Neurol. Sci.

Effect of mechanical rCBF reduction on EEG in man

Moderate hypoxic ischemia irreversibly damages rat brain in 30 minutes

Cellular oxygen requirements

Intracellular recording from cat spinal motoneurones during acute asphyxia

J. Physiol. (London)

Intracranial pressure changes in acute ischaemic regions of the primate hemisphere

Tissue pO2 and cell function in the microarea of the brain during hypoxia

Discussion report

Neurosciences Research Program

The relationship between cortical electrical activity, cerebral perfusion pressure and cerebral blood flow during increased intracranial pressure

Occlusion of the middle cerebral artery

Arch. Neurol. (Chicago)

Tissue pO₂ and cell function in the microarea of the brain during hypoxia