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Developmental and physiologic changes in cerebral blood flow velocity
I Horiuchi1, S Sanada, S Ohtahara
1Department of Child Neurology, Okayama University Medical School, Japan.
Insights
Mean blood flow velocity in the basilar artery changes with age in children, decreasing after age five. Transcranial Doppler sonography is a valuable tool for pediatric neurology research.
Area of Science:
- Neuroscience
- Pediatric Neurology
- Medical Imaging
Background:
- Cerebral blood flow regulation is crucial for brain development and function.
- Understanding age-related changes in cerebral hemodynamics is essential for diagnosing neurological conditions in children.
- Transcranial Doppler sonography (TCD) offers a noninvasive method to assess cerebral blood flow velocity (MBFV) and cerebrovascular resistance.
Purpose of the Study:
- To investigate the developmental changes in basilar artery (BA) mean blood flow velocity (MBFV) and resistance index (RI) in healthy Japanese children.
- To examine the impact of sleep (NREM and REM) and hyperventilation on BA and middle cerebral artery (MCA) MBFV.
- To compare the cerebrovascular response to hypercapnia in children versus adults.
Main Methods:
- Utilized transcranial Doppler sonography (TCD) to measure MBFV and RI in the BA and MCA of healthy Japanese subjects across various age groups.
- Recorded TCD parameters during wakefulness, non-rapid eye movement (NREM) sleep, rapid eye movement (REM) sleep, and hyperventilation.
- Assessed the cerebrovascular response to controlled hypercapnia (expiratory CO2 level of 25 mm Hg) in pediatric and adult cohorts.
Main Results:
- BA MBFV increased with age, peaking around 5 years, then gradually decreased. The MCA/BA MBFV ratio remained stable across age groups.
- BA RI was highest in infants, decreased in toddlers, and stabilized thereafter.
- MBFV was lower during NREM sleep compared to wakefulness; REM sleep showed similar values to wakefulness. Hyperventilation significantly reduced MBFV in both BA and MCA.
- Children exhibited a more pronounced decrease in MBFV during hyperventilation compared to adults (p < 0.05).
Conclusions:
- Cerebral blood flow dynamics undergo significant developmental changes in childhood, with distinct patterns in MBFV and RI.
- Sleep state influences cerebral hemodynamics, with reduced flow during NREM sleep.
- Children demonstrate a heightened cerebrovascular reactivity to hypercapnia, suggesting developmental differences in CO2 responsiveness.
- TCD is a valuable, noninvasive tool for assessing cerebral hemodynamics in pediatric populations, with potential applications in clinical neurology.
Abstract:
Developmental change of mean blood flow velocity (MBFV) and resistance index of the basilar artery (BA), as well as the changes in MBFV of the BA and the middle cerebral artery (MCA) during sleep and hyperventilation, were studied using transcranial Doppler sonography in healthy Japanese subjects. The MBFV of the BA increased with age from infancy through early childhood, reaching the maximum (64.4 +/- 2.6 cm/s) at the age of 5 y, and then gradually decreased. MBFV ratio of MCA to BA was almost stable between 1.57 to 1.64 in all age groups. The resistance index of the BA showed a maximum value in infants, decreased in 1- to 2-y-olds, and remained constant thereafter. The MBFV of both the MCA and BA were lower during non-rapid eye movement sleep than during wakefulness, whereas during rapid eye movement sleep they showed almost the same value as during wakefulness. They were also decreased during hyperventilation. At an expiratory CO2 level of 25 mm Hg (33.33 kPa), the average decrease in MBFV in children (n = 10) was -50.1 +/- 3.9% in the BA, and -46.2 +/- 7.4% in the MCA, significantly (p < 0.05) more marked than that in adults (n = 10) (-41.5 +/- 5.9% and -37.9 +/- 4.2%, respectively). Transcranial Doppler sonography is a noninvasive method that has a potentially wide range of applications in pediatric neurology.