The effects of raised ICP on lymph flow in the cervical lymphatic trunks in cats

Lymph was collected from cervical lymphatic trunks of anesthetized cats under conditions of normal cerebrospinal fluid (CSF) pressure and again when the CSF pressure was elevated by infusing artificial CSF into the subarachnoid space at the cisterna magna. There was an immediate increase in lymph flow on initiation of the CSF infusion, but this increase was not maintained although the CSF infusion continued. Lymph protein concentrations fell when the CSF infusion started and remained depressed while the infusion of CSF continued. It is postulated that under steady-state conditions much of the CSF leaving the subarachnoid space via the cranial nerves enters the capillaries from the extravascular spaces, and that large molecules from the CSF, such as proteins, return to the blood via the lymphatic system.