In-vivo experiments on respiratory-driven spinal CSF flow*

In recent years, respiration has been postulated as a major driving mechanism for the flow of cerebrospinal fluid (CSF) in the spinal canal. Previous studies have employed real-time phase-contrast magnetic resonance imaging (MRI) to investigate forced and extreme breathing maneuvers. The present work reports respiratory-gated MRI measurements of CSF flow in the spinal canal under normal, controlled breathing. Six different vertebral levels were considered for a set of healthy subjects. Results show cranial/caudal motion during inspiration/expiration, with large flow rates and stroke volumes at the lumbar and lower thoracic regions, where respiration-driven flow rates appear to be higher than previously reported cardiac-driven rates, the latter being dominant in the upper cervical region. Although significant differences are found between different subjects, the results suggest that the respiratory cycle should be accounted for in the full characterization of spinal CSF flow and associated transport rates.