DYNAMIC PROPERTIES OF LYMPHATIC PATHWAYS FOR THE ABSORPTION OF CEREBROSPINAL-FLUID

To study the dynamics of the outflow of cerebrospinal fluid (CSF) into the cervical lymphatic system, X-ray contrast medium or Indian ink wa s infused into the cisterna magna of rats at moderately increased intr acranial pressure (40-50 mmHg). In the first series of experiments, wh ile the contrast medium was being infused, the animal's head was exami ned using X-ray-microscopy (x 4-20 direct magnification radiography) a nd conventional radiography. Within the first minutes of infusion, the flow of CSF was directed from the posterior fossa to the olfactory bu lb. Reaching the cribriform plate approximately 7 min after starting t he infusion, the contrast medium leaked into the nasal cavities. Some minutes later, it opacified the subarachnoid space (SAS) of the optic nerve, the perilymphatic space of the inner ear, the cortical SAS, and the transverse sinuses. Leakage from the optic nerve SAS into the orb it was seen after 30 min infusion. In the second series of experiments , the Indian ink was infused after microsurgical exposure of the cervi cal lymph vessels. During the infusion the cervical lymph ducts were o bserved microscopically (x 40 magnification). Single dye particles dra ining through the cervical lymph ducts appeared 20 min after the start of cisternal infusion. Their transport was rapid, and dependent on th e respiratory cycle: during inspiration the particles moved at a speed of 10-20 mm/s, during expiration the movement stopped. Thus, rapid ki netics are demonstrated for the outflow of CSF and particles from the SAS into the cervical lymphatics.