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Cerebrospinal fluid (CSF) circulation describes the flow of the clear, odorless fluid from the brain and into the spinal column. CSF is made in the choroid plexus of the lateral ventricles of the brain, which is composed of capillaries with endothelial cells that have small openings within them. Cerebrospinal fluid circulation begins with the pulsing of the choroid plexus. Tiny cilia located on ependymal cells that also produce small amounts of CSF help propel the fluid along. It will eventually circulate throughout the subarachnoid spaces in the brain and spinal cord, and then be absorbed into the bloodstream.
CSF circulation occurs in a definite pattern. After the cerebrospinal fluid is produced, it flows through the interventricular foramens until it reaches the third ventricle of the brain. It then moves through the cerebral aqueduct and into the fourth ventricle, where it flows to the subarachnoid spaces of the brain and spinal cord. CSF also moves into the lymphatic vessels near the brain and spinal column.
The proper amount of circulating cerebrospinal fluid helps to protect the spinal cord and the brain from injury. CSF provides a protective layer that can absorb the shock from a sudden blow to the head or back. Too much CSF can put pressure on the intracranial blood vessels and disrupt the flow of fresh blood to the brain. Low amounts of circulating cerebrospinal fluid removes the protective cushioning around the brain and spinal cord, and can result in brain damage and hemorrhage if these areas are injured.
Normal cerebrospinal fluid circulation may also be interrupted by a variety of medical conditions. Hydrocephalus, which is the accumulation of fluid on the brain, puts pressure on the delicate brain tissue. The brain of most people with hydrocephalus is usually much smaller than normal, impeding the circulation of the cerebrospinal fluid throughout the brain.
Another condition that causes disruption to the normal circulation of CSF is called pseudotumor cerebri. The symptoms of this disorder are similar to those of a brain tumor, and include headache, nausea, and intermittent sounds being the main complaints. Also called benign intracranial hypertension, the inadequate absorption of CSF leads to a build-up of pressure within the skull. It may cause vision changes and eventual permanent vision loss due to the pressure on the optic nerve from the CSF.
Treatment of pseudotumor cerebri may require the surgical placement of a shunt to relieve the pressure from poor cerebrospinal fluid circulation. The shunt is placed in the lower spine and drains into the abdominal cavity. Excess cerebrospinal fluid is absorbed within the abdominal cavity, restoring normal cerebrospinal fluid circulation.