title: Use of a Codman microsensor intracranial pressure probe: effects on near infrared spectroscopy measurements and cerebral hemodynamics in rats.
abstract: Intracranial pressure (ICP) monitoring is indispensable in the assessment of neurotrauma in humans and animal models. It was shown that cerebellar ICP, leaving the cortical area intact, can replace cerebral ICP in rats. While cerebral probes may induce spreading depression, the effects of a miniature cerebellar probe on near infrared spectroscopy (NIRS) measurements and cerebral hemodynamics are not known. We therefore compared a group with an ICP probe to a control group. Our experiments revealed decreased optical path lengths at 840 nm and 960 nm (both p=0.026) and a decreased cerebral blood flow (CBF, p=0.015). Despite these changes, the data found using NIRS agree with the blood sample analysis. An increased deoxyhemoglobin concentration (p=0.041) and a decreased sagittal sinus oxygen saturation (p=0.041), were found in the ICP probe group. Because the decreased CBF was accompanied by an increased arterio-venous oxygen difference (p=0.026) and unaltered cerebral metabolic rate of oxygen (p=0.485), this suggests an uncoupling. These data suggest that a cerebellar miniature Codman ICP probe induces an uncoupling of cerebral metabolism and CBF. In addition, NIRS is found to be a robust technique: even when path lengths are altered after probe insertion, physiological alterations can still be examined.
authors.affiliation: Laboratory of Cardiovascular Research, Catholic University of Leuven, Leuven, Belgium.
authors.forename: Helga
authors.initials: H
authors.lastname: Blockx
authors.forename: Willem
authors.initials: W
authors.lastname: Flameng
authors.forename: Geofrey
authors.initials: G
authors.lastname: De Visscher
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D001921:Brain / Q000098:blood supply* / Q000378:metabolism; D002560:Cerebrovascular Circulation; D007427:Intracranial Pressure; D008297:Male; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D010100:Oxygen