Homogeneous cardiac-driven CSF flow in the cervical spine was noticed by 4D cardiac-gated phase-contrast flow MRI 10. Spinal and intracranial vascular pulsations were considered as the main factors initiating motion with cardiac pulsation most prevalent at cervical levels and increasing influence of respiration in thoracic and lumbar regions 9. 8 also referred to separate dynamic channels in the spinal CSF space with different flow directions. downward during inspiration and upward during expiration 7. Cardiac-related CSF oscillations were also measured in cervical segments of the spine with respiration-induced bulk flow superimposed and moving in separate channels, i.e. ![]() Early ECG-synchronized cine flow magnetic resonance imaging (MRI) studies also suggested a pulsatile nature of spinal CSF flow without net movement 5 or reported systolic-diastolic flow until the thoracolumbar junction but none below in lumbar regions 6. These results could not always be reproduced and other authors explained their pattern of tracer accumulation and uptake by pulsatile flow and mixing of CSF 4. described both a spinal ascent and in a later study a descent of CSF, which led to the postulation of a two-directional spinal CSF flow 3. Using radionuclide scintiphotographic techniques 1, 2, 3 Di Chiro et al. Thus, the pathogenesis of spinal cord developmental disorders like syringomyelia is vastly unknown. Moreover, diverse results have raised controversy and clinically relevant mechanisms of CSF flow in the spinal canal are still poorly understood. In contrast to intracranial and upper cervical spinal CSF flow, few studies have addressed CSF dynamics along the entire spine. In particular, the subarachnoid spaces of brain and spine communicate freely via the foramen magnum at the cranio-cervical junction. The compartments of the human CSF system are closely interconnected comprising the internal ventricular system, the subarachnoid spaces embedding the brain and the spinal cord. These observations most likely reflect closely coupled CSF and venous systems as both large caval veins and their anastomosing vertebral plexus react to respiration-induced pressure changes. The resulting pattern of net flow volumes during forced respiration yields upward CSF motion in the upper and downward flow in the lower spinal canal. While forced inspiration prompts upward surge of CSF flow volumes in the entire spinal canal, ensuing expiration leads to pronounced downward CSF flow, but only in the lower canal. Results reveal a watershed of spinal CSF dynamics which divides flow behavior at about the level of the heart. Here, we investigated CSF motion along the spinal canal by real-time phase-contrast flow MRI at high spatial and temporal resolution. Upward CSF flow into the head during inspiration counterbalances venous flow out of the brain. ![]() The dynamics of human CSF in brain and upper spinal canal are regulated by inspiration and connected to the venous system through associated pressure changes.
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