Distributions of Local Oxygen Saturation and Its Response to Changes of Mean Arterial Blood Pressure in the Cerebral Cortex Adjacent to Arteriovenous Malformations

Abstract

Background and Purpose-To test the hypothesis that neither "steal" as cortical ischemia caused by reduced perfusion pressure nor "breakthrough" on the grounds of loss of pressure autoregulation exist in brain tissue surrounding arteriovenous malformations (AVMs), we established patterns of cortical oxygen saturation (SO 2 ) adjacent to AVMs and its behavior after alterations of mean arterial blood pressure. Methods-With a microspectrophotometer, SO 2 was scanned in the cortex around AVMs of 44 patients before and after resection and in that of a non-AVM group (nϭ42) before transsylvian dissection. Autoregulation was evaluated by linear regression analysis after elevation of mean arterial blood pressure (5 g/min IV noradrenaline

Postoperative Hyperperfusion Associated With Steal Phenomenon Caused by a Small Arteriovenous Malformation-Case Report-

“…In our case, preoperative SPECT of the low perfusion area in the remote cortex fed by the main feeding artery demonstrated normal vasoreactivity to acetazolamide. Our observations are consistent with other investigations 10,15) that found the hypoperfusion area maintained the autoregulatory system and was not in misery perfusion. In addition, the anatomical factor of poor collateral flow in the temporal lobe is involved with the asymptomatic steal phenomenon in the ipsilateral temporal lobe.…”

“…3,5) There is solid evidence that AVMinduced reduction of cerebral perfusion pressure does not cause maximum reduction of cerebrovascular resistance in the adjacent cortex because further arteriolar relaxation was possible in all patients with AVM. 6,10) These observations are consistent with the hypothesis of adaptive autoregulatory displacement, that is, the lower limit of autoregulation shifts to a lower mean pressure in the chronic hypoperfusion area. 15) Increased capillary density may be another structural mechanism of adaptation.…”

In Vivo Tissue Diagnosis for Myocardial Infarction Using Optical Spectroscopy with Novel Spectral Interpretation Algorithms

“…The SatO 2 level of normal cortex reported here also agrees with a previously reported level [62]. It was noted that, in some cases, the SatO 2 level fluctuated significantly during the recording period, as shown in Figure 3-9.…”

Patterns of Cortical Oxygen Saturation Changes During CO 2 Reactivity Testing in the Vicinity of Cerebral Arteriovenous Malformations

“…7,9 The postoperative increase in oxygenation under steady-state conditions confirms that AVM resection leads to reactive hyperemia and tissue hyperoxia in the surrounding brain. 20,25,27 Therefore, it is not surprising that two thirds of patients showed an inverse CVR pattern after an increase in CO 2 in the AVM group. The degree of responsiveness was lower after surgery, reaching statistical significance for parallel behavior under induced vasodilation in AVM patients but not compared with postoperative controls.…”

“…Here, a so-called patchy hypoperfusion has been considered AVM specific 23 until proved otherwise 20,24,25 and now is well explained by theories regarding regulation of capillary circulation. 26 Compared with other modalities, the spatial resolution of our methods is higher.…”