Abstract
The spinal canal contributes to the overall compliance of the craniospinal compartment. Thus it plays an important role in the regulation of craniospinal hydrodynamics and intracranial pressure. Limited information is available concerning the spinal canal compliance and its distribution along the spinal canal. Current methods of compliance measurement require injection of fluid into the spinal canal cerebrospinal fluid (CSF) spaces and thus are associated with morbidity. A noninvasive method of deriving the spinal canal compliance and its distribution is being developed. A motion-sensitive Magnetic Resonance Imaging technique is employed to quantify the oscillating CSF flow at several locations along the spinal canal. The differential equations governing CSF flow are derived using Bond Graph methodology. Flow dynamics satisfying the differential equations is then compared iteratively with actual flow measurements to yield spinal canal compliance, and CSF resistance and inertia. The model was validated using CSF flow measurements obtained from 4 healthy volunteers. The model predicted CSF flow was compared with measured CSF flow waveforms at intermediate locations. Compliance values ranged from 1.7 mL/mmHg to 45.2 mL/mmHg. The model further provides new information about the relative contribution sub segments of the canal to the overall spinal canal compliance.
