It has been argued that stuff from the brain drains into the cervical lymph glands in your neck. This is important because it says that the immune system does not need to get into the brain to trigger autoimmunity so the outside-in (Where the immune response starts outside the brain and goes into the CNS as in EAE) and inside-out (MS starts in the brain and the immune system comes in, as suggested to occur in MS) arguments that the Animal modellers talk about is a waste of time. This because it is probably inside-outside-in. It was never logical that immune responses start in the brain, so I never wasted my time with this set of arguments. The lymph glands are designed to be a place where immune responses are generated, you don’t need to start generating them in places like the brain. However there was a question posed. If the cervical lymph glands in the neck are important for the brain drainage, where does the fluid from the spine drain to. Here it is reported to be in lymph glands in the abdomen.
Clearance of cerebrospinal fluid from the sacral spine through lymphatic vessels. Ma Q, Decker Y, Müller A, Ineichen BV, Proulx ST. J Exp Med. 2019 Aug 27. pii: jem.20190351.
The pathways of circulation and clearance of cerebrospinal fluid (CSF) in the spine have yet to be elucidated. We have recently shown with dynamic in vivo imaging that routes of outflow of CSF in mice occur along cranial nerves to extracranial lymphatic vessels. Here, we use near-infrared and magnetic resonance imaging to demonstrate the flow of CSF tracers within the spinal column and reveal the major spinal pathways for outflow to lymphatic vessels in mice. We found that after intraventricular injection, a spread of CSF tracers occurs within both the central canal and the spinal subarachnoid space toward the caudal end of the spine. Outflow of CSF tracers from the spinal subarachnoid space occurred predominantly from intravertebral regions of the sacral spine to lymphatic vessels, leading to sacral and iliac LNs. Clearance of CSF from the spine to lymphatic vessels may have significance for many conditions, including multiple sclerosis and spinal cord injury.