What Are the Functions of CSF?

Cerebrospinal fluid (CSF) is a clear liquid found in the central nervous system. CSF is produced by capillaries in the brain and the choroid plexus -- a structure in the ventricles of the brain. CSF circulates around the two hemispheres of the brain and the spinal cord. The amount of CSF in an average adult is between 100 to 150 ml. This CSF is completely replaced every 5 to 6 hours, because 500 ml are produced each day.

Cushioning

• The primary function of CSF is to provide cushioning for the central nervous system (CNS), comprised of the brain and spinal cord. These structures are responsible for directing all functions of the human body. The brain processes the five senses: smell, sight, hearing, touch and taste. The brain also produces emotions, thoughts, memory and feelings. Motor function for the body is powered by spinal nerves that emerge from the spinal cord. Cerbrospinal fluid keeps these structures lubricated and protected.

Homeostasis

• Homeostasis describes a state of equilibrium -- maintaining balance of an internal environment. Cerebrospinal fluid contributes to homeostasis in three ways. First, it maintains the physical environment by floating the brain and absorbing shock. Second, CSF maintains the chemical environment by preventing toxins in the blood from entering the central nervous system. Lastly, CSF brings nutrients to the brain and removes waste products from the brain.

Diagnosis of Illness

• The cerebrospinal fluid can be used to diagnose illness or pathological conditions. Lumbar puncture is used to obtain a fluid sample through a needle that is inserted into the lumbar (lower back) area of the spinal canal. The characteristics of the fluid are analyzed -- glucose, protein, cell count and fluid pressure -- to check for abnormalities. In addition, the CSF is tested for the presence of infection. This diagnostic procedure is used to check for inflammation in the central nervous system or surrounding structures, increased pressure in the brain, bleeding in the brain, tumors and immune disease.

Hydrocephalus

• The most common cerebrospinal fluid pathology is hydrocephalus -- "water on the brain". This condition can exist at birth or develop later on. Hydrocephalus is excessive CSF in the brain that affects brain development or function. It is characterized by an abnormally large head (in children), vomiting, irritability, developmental delays, urinary incontinence, confusion, balance and coordination issues, fatigue and personality changes. Hydrocephalus is typically treated with surgical implantation of a shunt to drain the excess fluid from the brain into another area of the body. Rehabilitation therapies are used to treat the dysfunction caused by the hydrocephalus.