Postural Effects on Brain Hemodynamics in Unilateral Cerebral Artery Occlusive Disease: A Positron Emission Tomography Study

Abstract

To investigate effect of assuming of upright posture on brain hemodynamics in patients with unilateral internal carotid or middle cerebral artery occlusion (MCAO), local tissue oxygen extraction fraction (OEF), and postural changes in regional cerebral blood flow (rCBF) during supine and sitting conditions were examined using positron emission tomography (PET) with (15)O-gas steady-state method and H(2)(15)O autoradiographic method. A total of 22 minor stroke patients at relatively early stages participated. The regions of interest method was used for analyzing levels of perfusion and oxygen metabolic parameters, and postural rCBF change within MCAO group was investigated using statistical parametric mapping. Region of interest analyses showed significant rCBF reduction in the cortical and subcortical regions distal to the artery occlusion in CAO patients during sitting. Regression analyses showed that magnitudes of rCBF reduction in those areas were correlated positively with OEF values and inversely with metabolic rates of oxygen (P < 0.05). Statistical parametric mapping for MCAO patients demonstrated further rCBF reduction by sitting in the occlusion-side MCA territory. The current study suggested that assumption of upright posture could exert an adverse effect on local perfusion in hemodynamically compromised patients with major cerebral vessel occlusion, possibly caused by impairment of local autoregulation.

Orthostatic Cerebral Hypoperfusion Syndrome

“…Other syndromes that are associated with orthostatic dizziness or orthostatic intolerance without orthostatic hypotension were ruled out in this study. These syndromes include orthostatic tachycardia syndrome (Low et al, 2009 ), inappropriate sinus tachycardia (Yusuf and Camm, 2005 ), large cerebral vessel disease (Ouchi et al, 2001 ), and deficit in sensory systems, including vestibular dysfunction, vision impairment, or disorders in the proprioceptive system (Wu et al, 2008 ). POTS and syncope patients were removed from this study by exclusion criteria.…”

Acute Stroke: Current Evidence-based Recommendations for Prehospital Care

“… 59 , 60 The sitting position in patients who had suffered strokes caused reduced blood flow distal to the occlusion. 61 When measured with tissue oxygenation index, cerebral oxygenation dropped in the upright patient and rose in the supine patient. 62 Factors such as secretions, congestive heart failure, or respiratory distress frequently confound the acute stroke patient and preclude laying the patient flat because of effects on oxygen saturation and secretions.…”

Brain Serotonin Transporter Density and Aggression in Abstinent Methamphetamine Abusers

“…3,18,40,41 An investigator masked to the participant's condition placed 10 ROIs bilaterally over the midbrain, thalamus, caudate nucleus, putamen, amygdala, anterior cingulate cortex, dorsolateral prefrontal cortex, orbitofrontal cortex, temporal cortex, and cerebellar cortex on the MRIs, as previously described. 40,42,43 After delineation of the ROIs was completed on the reformatted MRIs, the PET images were displayed side-by-side with the MRIs. Then, the determined ROIs were placed on the same area on the MRIs and the corresponding PET images.…”