Effect of Normal Breathing on the Movement of CSF in the Spinal Subarachnoid Space

Abstract

BACKGROUND AND PURPOSE: Forced respirations reportedly have an effect on CSF movement in the spinal canal. We studied respiratory-related CSF motion during normal respiration. MATERIALS AND METHODS:Six healthy subjects breathed at their normal rate with a visual guide to ensure an unchanging rhythm. Respiratory-gated phase-contrast MR flow images were acquired at 5 selected axial planes along the spine. At each spinal level, we computed the flow rate voxelwise in the spinal canal, together with the associated stroke volume. From these data, we computed the periodic volume changes of spinal segments. A phantom was used to quantify the effect of respiration-related magnetic susceptibility changes on the velocity data measured.RESULTS: At each level, CSF moved cephalad during inhalation and caudad during expiration. While the general pattern of fluid movement was the same in the 6 subjects, the flow rates, stroke volumes, and spine segment volume changes varied among subjects. Peak flow rates ranged from 0.60 to 1.59 mL/s in the cervical region, 0.46 to 3.17 mL/s in the thoracic region, and 0.75 to 3.64 mL/s in the lumbar region. The differences in flow rates along the canal yielded cyclic volume variations of spine segments that were largest in the lumbar spine, ranging from 0.76 to 3.07 mL among subjects. In the phantom study, flow velocities oscillated periodically during the respiratory cycle by up to 0.02 cm/s or 0.5%. CONCLUSIONS:Respiratory-gated measurements of the CSF motion in the spinal canal showed cyclic oscillatory movements of spinal fluid correlated to the breathing pattern.

Effects of buoyancy on the dispersion of drugs released intrathecally in the spinal canal

“…For instance, the recent experiments of Ayansiji et al (2023) have shown that the presence of nerve roots significantly promotes tracer dispersion. The effect of trabeculae, which form a continuous weblike structure stretching across the spinal canal (Mortazavi et al 2018), can be modelled by adding a distributed Brinkman flow resistance term to the momentum equation, as done earlier (Gupta et al 2008;Tangen et al 2015;Sincomb et al 2022). Nerve roots and ligaments, on the other hand, are arranged in quasi-periodic rows aligned along the canal.…”

“…2019; Gutiérrez-Montes et al. 2022), thereby possibly promoting drug dispersion near the injection site. Also important is the effect of the different micro-anatomical features that populate the spinal canal, such as denticulate ligaments, nerve roots and trabeculae (Stockman 2006; Gupta et al.…”

“…The CSF moves along the canal with an oscillatory velocity that is synchronized with the cardiac and respiratory cycles. The CSF oscillatory flow is more pronounced near the canal entrance, where the characteristic velocities u c are of the order of a few cm s −1 , but become progressively smaller on approaching the closed end of the canal, as revealed by in vivo magnetic resonance measurements (Haughton & Mardal 2014;Aktas et al 2019;Coenen et al 2019;Sincomb et al 2022). The following analysis focuses specifically on the flow induced by the cardiac cycle, corresponding to angular frequencies ω 2π s −1 and characteristic stroke lengths L s = u c /ω ∼ 1 cm that are much smaller than the canal length L.…”

An analytic model for the flow induced in syringomyelia cavities

“…It is now well established that CSF displays an oscillatory motion in the subarachnoid space (SAS) surrounding the spinal cord, as indicated in figure 1(d). The oscillatory velocities, with peak values of the order of a few centimetres per second, are driven by the respiratory and cardiac cycles (Linninger et al 2016;Kelley & Thomas 2023), with the former being dominant in the lumbar region (Gutiérrez-Montes et al 2022) and the latter being dominant in the cervical region (Yildiz et al 2017(Yildiz et al , 2022, where most syrinxes are formed.…”

“…2016; Kelley & Thomas 2023), with the former being dominant in the lumbar region (Gutiérrez-Montes et al. 2022) and the latter being dominant in the cervical region (Yildiz et al. 2017, 2022), where most syrinxes are formed.…”