Dural Pulsations in the American Alligator Influence the CSF Dynamics Between the Cranial and Spinal Compartments

Background/Introduction: At the foramen magnum of the American alligator (Alligator mississippiensis), the central nervous system is surrounded by three concentric and continuous layers: the cerebrospinal fluid (CSF), the dura, and venous blood in sinuses. The present study examined how this spatial arrangement influenced the dura. Methods: Pressure recordings from CSF and venous blood were taken simultaneously with laser vibrometric analysis of dural and spinal venous sinus displacement. Results: In the cranial compartment, the cardiac-related pulsations in the CSF induce similar pulsations in the dura, while during ventilation, the dura withdraws from the skull even as the pressure increases in the cranial CSF. Below the foramen magnum, the pulsatile displacement of the spinal venous sinus matches the pattern of the CSF pressure and the dura, but is not aligned with the venous blood pressure. There is an intrinsic pattern of dural movement that greatly influences the dynamics of the CSF and spinal venous blood. Conclusions: By measuring both the displacement of the dura and the underlying CSF pressure, the study confirmed early findings of low compliance within the CSF system of the alligator. The findings of the present study may offer insight into the best practices for duraplasty and the treatment of dural leaks.