BACKGROUND: Slow oscillations of cerebral blood flow induced by synchronous variations of arterial blood pressure (ABP) are often used for clinical assessment of cerebral autoregulation. In the alternative scenario, spontaneous cerebral vasocycling may produce waves in cerebral blood flow that are, to a large extent, independent of ABP fluctuations. We use wavelet analysis to test the latter hypothesis. METHODS: The wavelet variability V(f), defined as the time averaged moduli of frequency dependent wavelet coefficients, is employed to analyze the relation between dynamics of arterial blood pressure and that of cerebral blood flow velocity in middle cerebral artery (MCA). FINDINGS: In the very low frequency (VLF, 0.02-0.07 Hz) band the variability in traumatic brain injury (TBI) patients with low intracranial pressure (V(ABP) = 0.36 +/- 0.28) is significantly smaller than that of the volunteers (V(ABP) = 0.70 +/- 0.25) with p = 7 x 10(-5). Interestingly, the corresponding variabilities of MCA flow velocity for both cohorts are comparable. V(MCA) = 0.83 +/- 0.65 of the brain injury patients is not statistically different from that of the volunteers V(MCA) = 1.06 +/- 0.41 (p = 0.11). CONCLUSIONS: In TBI patients without cerebral hypertension, the VLF oscillations must have been spontaneously generated within intracranial volume to compensate for the reduced ABP variability. Vasomotion is identified as a plausible physiological mechanism underlying such oscillations. We argue that vasomotion may be beneficial for brain tissue oxygenation especially during periods of critically low perfusion.
BACKGROUND: Slow oscillations of cerebral blood flow induced by synchronous variations of arterial blood pressure (ABP) are often used for clinical assessment of cerebral autoregulation. In the alternative scenario, spontaneous cerebral vasocycling may produce waves in cerebral blood flow that are, to a large extent, independent of ABP fluctuations. We use wavelet analysis to test the latter hypothesis. METHODS: The wavelet variability V(f), defined as the time averaged moduli of frequency dependent wavelet coefficients, is employed to analyze the relation between dynamics of arterial blood pressure and that of cerebral blood flow velocity in middle cerebral artery (MCA). FINDINGS: In the very low frequency (VLF, 0.02-0.07 Hz) band the variability in traumatic brain injury (TBI) patients with low intracranial pressure (V(ABP) = 0.36 +/- 0.28) is significantly smaller than that of the volunteers (V(ABP) = 0.70 +/- 0.25) with p = 7 x 10(-5). Interestingly, the corresponding variabilities of MCA flow velocity for both cohorts are comparable. V(MCA) = 0.83 +/- 0.65 of the brain injurypatients is not statistically different from that of the volunteers V(MCA) = 1.06 +/- 0.41 (p = 0.11). CONCLUSIONS: In TBIpatients without cerebral hypertension, the VLF oscillations must have been spontaneously generated within intracranial volume to compensate for the reduced ABP variability. Vasomotion is identified as a plausible physiological mechanism underlying such oscillations. We argue that vasomotion may be beneficial for brain tissue oxygenation especially during periods of critically low perfusion.
Authors: María García; Jesús Poza; David Santamarta; Roberto Romero-Oraá; Roberto Hornero Journal: Philos Trans A Math Phys Eng Sci Date: 2018-08-13 Impact factor: 4.226
Authors: Béla Horváth; Gábor Lenzsér; Balázs Benyó; Tamás Németh; Rita Benko; András Iring; Péter Hermán; Katalin Komjáti; Zsombor Lacza; Péter Sándor; Zoltán Benyó Journal: PLoS One Date: 2010-12-31 Impact factor: 3.240
Authors: Afrouz A Anderson; Elizabeth Smith; Fatima A Chowdhry; Audrey Thurm; Emma Condy; Lauren Swineford; Stacy S Manwaring; Franck Amyot; Dennis Matthews; Amir H Gandjbakhche Journal: Front Neurosci Date: 2017-05-30 Impact factor: 4.677