Spinal CSF flow in response to forced thoracic and abdominal respiration, 2019, Aktas et al

Spinal CSF flow in response to forced thoracic and abdominal respiration
Gökmen Aktas, Jost M. Kollmeier, Arun A. Joseph, Klaus-Dietmar Merboldt, Hans-Christoph Ludwig, Jutta Gärtner, Jens Frahm, Steffi Dreha-Kulaczewski

Background
Respiration-induced pressure changes represent a powerful driving force of CSF dynamics as previously demonstrated using flow-sensitive real-time magnetic resonance imaging (MRI). The purpose of the present study was to elucidate the sensitivity of CSF flow along the spinal canal to forced thoracic versus abdominal respiration.

Methods
Eighteen subjects without known illness were studied using real-time phase-contrast flow MRI at 3 T in the aqueduct and along the spinal canal at levels C3, Th1, Th8 and L3. Subjects performed a protocol of forced breathing comprising four cycles of 2.5 s inspiration and 2.5 s expiration.

Results
The quantitative results for spinal CSF flow rates and volumes confirm previous findings of an upward movement during forced inspiration and reversed downward flow during subsequent exhalation—for both breathing types. However, the effects were more pronounced for abdominal than for thoracic breathing, in particular at spinal levels Th8 and L3. In general, CSF net flow volumes were very similar for both breathing conditions pointing upwards in all locations.

Conclusions
Spinal CSF dynamics are sensitive to varying respiratory performances. The different CSF flow volumes in response to deep thoracic versus abdominal breathing reflect instantaneous adjustments of intrathoracic and intraabdominal pressure, respectively. Real-time MRI access to CSF flow in response to defined respiration patterns will be of clinical importance for patients with disturbed CSF circulation like hydrocephalus, pseudotumor cerebri and others.

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One of the more technically satisfying (and occassionally artistic) imaging studies for paediatric radiologists is neonatal spine ultrasonography, which highlights the dynamic appearance of spinal nerve roots. Before the midline neural arch starts to mineralise by around 6 weeks, neonates give us a very good sonographic window to their intraspinal compartment. An example of where ultrasound as a high-resolution, real-time modality can beat MRI.

You can see the pulsatility of the cauda equina. Baby is lying prone, so that increases intraabdominal pressure, superimposed on the cardiac and respiratory cycles.

Here are some brief cine-loops of what this looks like —

https://www.youtube.com/watch?v=lPNuJhimjX0

https://www.youtube.com/watch?v=1ew6rMprQsQ

Related links —
https://ultrasoundpaedia.com/neonatal-spine-normal/
Ultrasound of congenital spine anomalies (2021, Ped Radiol, pay-walled)