Pathophysiology of tumor spread into the leptomeningeal space

The figure at the left illustrates a metastasis to the skull (A), with cells infiltrating through the dura into the subarachnoid space (B), and subsequently down the Virchow-Robin spaces into the brain (C). Cells may also be found circulating in the blood as seen in the sagittal sinus (D). The figure at the right illustrates tumor cells entering the subarachnoid space from the paravertebral space along nerve sheaths (E) or from the vertebral body through connecting blood vessels (F).