In this condition, the prenatal spinal deformities result in only the meninges, and not the spinal nerves, slipping into the gaps between the deformed vertebrae.
The first way is direct spread, which is when a pathogen gets inside the skull or spinal column, and then penetrates the meninges, eventually ending up in the CSF.
So the meninges, which is the covering of the brain, as well as the blood vessels in the head and the muscles in the head and neck all have pain fibers.
So all that goo is well-protected by the bones of your vertebrae and cranium, as well as membrane layers, or meninges, before being bathed in a cushy waterbed of clear cerebrospinal fluid.
This constitutes a defect or absence of the vertebral arches, due to failure of mesoderm to organize over the region of the defect, and it may or may not involve the underlying meninges and neural tissue.
After the fourth ventricle, the cerebrospinal fluid enters the subarachnoid space, which is the space between the arachnoid and pia mater, two of the inner linings of the meninges which cover and protect both the brain and the spine.