Cerebral cortical and white matter reactivity to carbon dioxide.

Abstract

We measured cerebrovascular reactivity to carbon dioxide in the cerebral cortex and the subcortical white matter of 12 healthy adult volunteers (four young subjects aged 21-24, four middle-aged subjects aged 34-40, and four elderly subjects aged 62-85 years). Blood flow was computed from the concentration history of xenon-133 in the volume of interest measured with an ultrapure germanium detector array. End-tidal PacOj ranged from 35.4 to 42.6 mm Hg. The mean±SD baseline blood flows hi the cerebral cortex were 60±7, 51 ±9, and 33±4 ml/100 cm 3 / min in the young, the middle-aged, and the elderly subjects, respectively; the corresponding subcortical white matter baseline blood flows were 21±1, 22±3, and 16±5 ml/100 cnrVmin. Mean±SD cerebrovascular reactivities to carbon dioxide in the cerebral cortex were 2.03±0.58, 1.36±0.41, and 0.72±0.19 ml/100 cm 3 /min/mm Hg PacOj for the young, the middle-aged, and the elderly subjects, respectively; the corresponding reactivities in the subcortical white matter were 0.69±0.11, 0.59±0.17, and 0.36±0.41 ml/100 cm 3 /min/mm Hg PacOj. Blood flow and cerebrovascular reactivity in the cerebral cortex of the young subjects were significantly higher than those for white matter and significantly higher than those in the elderly subjects (p<0.001). Age vs. blood flow (for the cortex) and age vs. cerebrovascular reactivity (for both cortical gray and subcortical white matter) also showed significant linear correlation (/><0.05). However, the age-related changes hi white matter blood flow and cerebrovascular reactivity were slow, and the differences among the age groups were not statistically significant. (Stroke 1989^0:453-457)

Tissue Pulsatility Imaging of Cerebral Vasoreactivity During Hyperventilation

“…The tissue pulsatility response to hypocapnia appears to decrease with age although with only four subjects, it is not possible to conclude that this trend is real and significant. This is consistent, however, with other studies that indicate a decrease in CVR with age (Reich and Rusinek 1989;Tsuda and Hartmann 1989;Yamaguchi et al 1979) and age-related cerebrovascular disease (Groschel et al 2007). …”

Cerebral blood flow and cerebrovascular reactivity at rest and during sub-maximal exercise: Effect of age and 12-week exercise training

“…Influence of age on cerebral blood flow and cerebrovascular reactivity at rest and during exercise Older individuals have been reported to have a maintained (Davis et al 1983;Ito et al 2002;Kastrup et al 1998;Schwertfeger et al 2006;Galvin et al 2010) and reduced (Reich and Rusinek 1989;Yamamoto et al 1980) hypercapnic cerebrovascular reactivity compared to younger individuals. The reasons for the discrepancy are likely to be multi-factorial and may include differences in CBF measurement technique (i.e.…”

“…The effect of healthy ageing on cerebrovascular CO2 reactivity is less clear, however. Hypercapnic reactivity has been found to be both lower (Reich and Rusinek 1989;Yamamoto et al 1980) and unchanged (Davis et al 1983;Ito et al 2002;Kastrup et al 1998;Schwertfeger et al 2006;Galvin et al 2010) with advancing age, while hypocapnic reactivity has been found to be elevated (Galvin et al 2010), unchanged (Ito et al 2002) and reduced (Yamaguchi et al 1979;Tsuda and Hartmann 1989). Differences in measurement technique, stimulus magnitude (i.e.…”

Effect of Non-Steady-State Perfusion on Xenon-133 Cerebral Blood Flow Measurements: An Analytical Study

“…Testing CO2 responsiveness is an other application where blood flow changes are quantified. In this case, however, not only gray matter but also white matter perfusion rates are in creased, both with very similar reactivities (Reich and Rusinek, 1989). In addition, it has been demon strated in experimental studies that CO2 responsive ness under conditions of hypercarbia and hypocar bia are of approximately equal magnitude (Sieber et aI., 1989).…”