Systems for treating along the central nervous system

SYSTEMS, CATHETERS, AND METHODS FOR TREATING ALONG THE CENTRAL NERVOUS SYSTEM Cross Reference to Related Applications Systems, catheters, and methods for accessing and treating along the central nervous system are disclosed including sampling systems. An example sampling system may include a filter cassette designed to filter cerebrospinal fluid. The filter cassette may have an inlet region configured to be coupled to a catheter and configured to receive cerebrospinal fluid, one or more filters, and an outlet region configured to be coupled to an outlet of the catheter and to direct filtered cerebrospinal fluid to the catheter. A sampling port may be in fluid communication with the filter cassette. The sampling port may have a first end region configured to receive cerebrospinal fluid, a stopcock, a syringe port, and a second end region. The stopcock may be configured to shift between a first position where cerebrospinal fluid is directed from the first end region to the second end region and a second position where cerebrospinal fluid is directed from the first end region to the syringe port.