Continuous positive airway pressure alters cranial blood flow and cerebrospinal fluid dynamics at the craniovertebral junction

Abstract

Keywords:Cerebral blood flow Cerebrospinal fluid dynamics Spinal subarachnoid space Cerebral autoregulation Cervical spine Continuous positive airway pressure Sleep apnea Intrathoracic pressure Craniospinal compliance PtcCO 2 2D phase-contrast MRI Purpose: To investigate the impact of continuous positive airway pressure (CPAP) applied by a full-face fitted mask at 15 cmH 2 O on total cerebral blood flow (tCBF), jugular venous flow (tJVF) and cerebrospinal fluid (CSF) flow. Materials and methods: Axial 2D phase-contrast MRI measurements were acquired at the C2-C3 vertebral level for 23 healthy male awake subjects at baseline (without) and with CPAP applied. CSF flow was quantified within the spinal subarachnoid space and tCBF was quantified based on the summation of blood flow within the left and right internal carotid and vertebral arteries. tJVF was quantified based on the summation of blood flow within the left and right jugular veins. Heart rate, transcutaneous carbon dioxide (PtcCO 2 ) and oxygen saturation were continuously monitored during the MR protocol. Results: CPAP decreased the pulse amplitude (PtPPA) of tJVF by 21% (p = 0.004). CSF stroke volume (SV) and PtPPA also decreased by 20% (p = 0.003) and 15% (p = 0.005), respectively. Change in tCBF SV and PtPPA was not significant. However, the timing of maximum systolic tCBF occurred significantly earlier under CPAP. CSF flow and tJVF waveforms showed significant spatial and temporal differences in waveform feature points, and spectral analysis revealed a decrease in the first harmonic of tJVF under CPAP (p = 0.001). Under CPAP, a 5% decrease in PtcCO 2 (p = 0.003) and 9% increase in HR (p = 0.006) were measured. However, these HR and PtcCO 2 changes were not correlated with any changes in arterial, venous or CSF flow dynamics. Conclusion: Application of CPAP via a full-fitted mask at 15 cm H 2 O was found to have a significant effect on intracranial venous outflow and spinal CSF flow at the C2 vertebral level in healthy adult-age awake volunteers. CPAP can be used to non-invasively provoke changes in intracranial and CSF flow dynamics.

Cerebrospinal fluid and blood flow patterns in idiopathic normal pressure hydrocephalus

“…In general, our CSF stroke volumes are somewhat higher, while our flow delays are somewhat lower, than those presented in the literature . This emphasizes that differences in spatial and time resolution, V enc , and even the approach to drawing the ROI, are important for the magnitude of such values.…”

“…Our study employed a higher encoding velocity than previous studies of aqueduct CSF net flow, which may explain some of the difference in the results. Some improvement in the reliability of this type of measurement may be achieved using PC‐MR sequences with multipoint velocity encoding . To provide a definitive answer as to whether the reversed CSF circulation is a component of the INPH pathophysiology, an alternative measurement technique is likely needed, for example, based on several repeated measurements or a long duration measurement.…”

Quantification of Arterial, Venous, and Cerebrospinal Fluid Flow Dynamics by Magnetic Resonance Imaging Under Simulated Micro-Gravity Conditions: A Prospective Cohort Study

“…Similarly, the internal carotid and vertebral arteries do not account for the entirety of arterial inflow to the head, and so the observed decrease in arterial inflow seen with HDT could also be due to diversion of arterial blood flow to other vessels. An alternative explanation could be due alterations in carbon dioxide levels due to anxiety and increased respiration while in HDT: Yiallourou et al previously had similar findings in changes in intracranial flow following alterations to carbon dioxide levels with the application of continuous positive airway pressure [31]. An additional limitation was that, due to time constraints, we did not repeat the scan protocol afterwards again in the supine position to assess for a return to baseline.…”

Sleep-Disordered Breathing and Idiopathic Normal-Pressure Hydrocephalus: Recent Pathophysiological Advances

“…The statistically significant association of OSA with NPH is relatively novel [ 18 •• ] but the physiopathological vascular and metabolic mechanisms have been amply supported in the literature [ 66 – 71 , 74 – 80 ]. For instance, pulmonary hypertension is a well-known effect of OSA [ 82 ] and positive end-expiratory pressure (PEEP) [ 83 – 85 ] can increase central venous pressure, decreasing outflow and elevating intracranial CSF pressure. Frydrychowski et al [ 86 ] showed that acute increases in jugular vein pressure induce elevation of intracranial CSF pressure.…”