Regional blood flow, plasma volume, and vascular permeability in the spinal cord, the dural sac, and lumbar nerve roots

Objectives. This study quantified the regional blood flow (RBF), plasma volume (PV), and the vascular permeability (VP) in the spinal cord, spinal nerve roots, and the dural sac. Summary of Background Data. Spinal cord hemodynamics have been investigated. However, the full segmental distribution of blood flow to the spinal cord and nerve roots has not been worked out. Vascular permeability of the spinal cord and nerve roots has been investigated but results regarding the spinal nerve roots have not been consistent. Methods. Eight Labrador dogs were used. Regional blood flow was measured with microspheres. Plasma volume and vascular permeability were assessed by the distribution spaces of radioactively labeled plasma proteins. Results. Regional blood flow was highest in the cervical and lumbar cord. Average (SEM) RBF values of the cord and spinal nerve roots were 10.4 ± 1.0 and 4.4 ± 0.5 mL/min 100 g, respectively. Plasma volume of the spinal cord was 0.85 ± 0.06 mL/100 g and 1.29 ± 0.17 mL/100 g in the spinal nerve roots. Vessels in the spinal nerve roots had significantly greater permeability to albumin than those of the spinal cord (P< 0.001). Conclusions. The quantitative flow measurements showed the existence of three main anatomic territories in the cord. The vascular permeability of vessel in the spinal nerve roots appears greater than that of the spinal cord, indicating that spinal nerve roots are located outside the blood brain barrier. Diffusion might be one of the nutritional pathways to spinal nerve roots.