A study published in Science Advances provides evidence that cerebrospinal fluid (CSF) is not contained to the brain and spinal cord—it can potentially travel throughout the nervous system.
“Our results support a contiguous and continuous CSF flow system from the CNS [central nervous system] to the distal ends of peripheral nerves, a function likely integral in sustaining peripheral nerves through delivery of nutrients and removal of waste,” wrote Alexander P. Ligocki, Ph.D., of the University of Florida, and colleagues.
Ligocki and colleagues injected tiny gold particles (about 2 nanometers in size) containing a tracer dye into the lateral ventricles—CSF-filled chambers within the brain—of laboratory mice. While the particles initially dispersed across the brain and spinal cord, within four to six hours they had spread into peripheral nerves such as the trigeminal nerve that controls facial sensations and the sciatic nerve that runs down the back of each leg. The particles were contained in the endoneurium—a fluid-filled sheath of connective tissue that surrounds nerve bundles.
Larger, 15-nanometer gold particles did not escape the central nervous system but collected in the brainstem and spinal cord near the origins of peripheral nerves. The researchers also injected the tiny gold particles into the veins of the mice and did not observe any tracer dye in peripheral nerves, indicating the particles were not passing through the blood-brain barrier and traveling through the blood stream.
“The presence of a contiguous CSF flow route from the CNS along peripheral nerves has far-reaching implications for peripheral nerve health and neuropathologies,” Ligocki and colleagues wrote. They noted, for example, that a continuous flow system may explain why diseases like Alzheimer’s or Parkinson’s can be associated with loss of feeling in the hands or feet—because disturbances in CSF pressure in the brain will spread throughout the body.
“Furthermore, our results suggest that infusion into the CSF compartment may be an efficacious method for direct delivery of drugs and therapeutic agents to peripheral nerves,” the researchers added.
(Image: Getty Images/iStock/PALMIHELP)
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