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KMID : 0350519940470041665
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Journal of Catholic Medical College
1994 Volume.47 No. 4 p.1665 ~ p.1678
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The Effect of Hypertension and the Increased Infratentorial Intracranial Presure on Frontal Cortex, Pontine Cerebral Blood Flow and Auditory Evoked Potentials in Experimental Cat Models
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Abstract
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Patients with extra-axial mass lesions of the posterior fossa frequently demonstrate signs of brain-stem dysfunction. These dysfunctions due to mass lesions may be induced by change of regional cerebral blood flow and electrophysiological states
as
well
as mechanical compression and distortion of the brainstem. There have been a few studies that the elevation of mean arterial blood pressure (MABP) may affect the brainstem function by improving cerebral perfusion pressure.
Frontal cortical regional cerebral blood flow(rCBF), pontine rCBF, brainstem auditory evoked potentials(AEPs), and MABP were recorded before and after expansion of an infratentorial epidural ballon in anesthetized experimental cat models.
Especially
infratentorial intracranial pressure (infratentorial ICP) was monitored intraparenchymally. 60 cats weighing 2.3-4.5kg were divided into 6 groups. In the control groups(group 1: 15-20mmHg, group 2: 30-35 mmHg, group 3: 45-50 mmHg of
infratentorial
ICP),
the changes of rCBF, AEPs and MABP without hypertension were studied. In the experimental groups, recovery of rCBF, AEPs when MABP was elevated at 60 minutes after elevation of infratentorial ICP(group 4: 15-20mmHg, group 5: 30-35mmHg, group 6:
45-50
mmHg) were studied.
@ES The results were as follows:
@EN 1. In group 1 and 2, the frontal cortical rCBF were decreased significantly at 120, 180 min after elevation of infratentorial ICP, but the pontine rCBF were not changed in spite of the elevated infratentorial ICP. I-iii and iii-v interpeak
latencies
in group 1 were prolonged significantly at 60 min after elevation of infratentorial ICP. In group 2, interpeak latency was significantly prolonged in I-iii wave at 60 min and in iii-v wave immediately after elevation of infratentorial ICP. In
group
3,
the frontal cortical and pontine rCBF, AEPs were significantly changed immediately after elevation of infratentorial ICP.
2. In group 4, the frontal cortical and pontine rCBF, iii-V interpeak latency were not changed when MABP was elevated during increased infratentorial ICP. In group 5, the frontal cortical rCBF recovered 81% of the control value at 60 min, 86% at
120
min after elevation of MABP. iii-V interpeak latency also recovered 85% of the control value at 60 min, 88% at 120 min after elevation of MABP. In group 6, frontal cortical and pontine rCBF, iii-V interpeak latency did not recoverd in spite of
the
elevated MABP.
3. The irreversible change in the frontal cortex and pons was noted when the infratentorial ICP reached over 45-50 mmHg level.
The results suggests that the elevation of MABP for improving cerebral perfusion pressure before irreversible change of the brain could preserve cerebral function, and assist to recover from decreased cerebral function. We conclude that if we can
estimate the volume of the space occupying mass in the posterior fossa, we are able to prevent brain damage from low rCBF and brain compression due to intracranial hypertension by the elevation of MABP before irreversible damage.
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KEYWORD
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